Screw chillers having air-cooled screw chiller and water-cooled screw chiller in terms of cooling method.
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Compared with scroll compressor chillers, screw chillers with large cooling capacity for some certain industrial or commercial usage.
Both types of these two screw chillers are widely used for various industries applications such as HAVC, big building&hotel air conditioning, central chilled water supply, chemical processing, die casting,food&beverage processing, pet food, Pharmaceutical, plastic processing, automotive, energy&power project, packing, and printing'
Screw chiller expertise is common in all major industries, it uses the screw compressor to get this name.
The utility of screw chiller has the advantages of large power, compact structure, stable operation, simple operation, and wide application range, and is suitable for large air conditioners such as hotels, hotels, factories, hospitals, etc., especially in high-rise buildings with less load, and can display its uniqueness superiority.
A screw chiller is an industrial chiller with a screw-type compressor.
Like all chilling systems, screw chillers are composed of an evaporator, compressor, condenser, expansion valve.
What sets it different from other types of chillers is its screw-type compressor, which uses two helical rotors that propel and compress the refrigerant vapor.
Because of fewer moving parts and the rotary motion, screw chillers are more durable and quiet. They are smaller and lighter and are a popular choice by the users.
Screw chillers can be applied in a variety of cooling applications and are reliable for heavy-duty performance under harsh conditions and the environment.
Regardless of which type of compressor, all of them have one common function-converting a source of power into stored energy in the form of compressed air.
Simply speaking, a compressor sucks in enough air and decreases its volume.
As a result both the temperature and pressure rise. Most air compressors either are reciprocating piston type or rotary screw type.
2.1 Reciprocating Chiller
A reciprocating compressor has a piston move downwards, reducing the pressure in its cylinder by creating a vacuum.
This difference in pressure forces the cylinder door to open and bring gas in. When the cylinder goes back up, it increases pressure, thus forcing the gas back out. The up-and-down motion is called reciprocating motion.
There are a lot of moving parts like piston, piston ring, crankshaft, connecting rod, valves, etc. that cause lesser reliability and more chance of breakdown.
The internal temperature at which the pistons operate is around 150 to 200 Deg C. This is because of the friction generated by the contact of piston rings against the cylinder walls.
The space required by the piston compressor is more. A separate screw-type compressor compartment is needed for its noise and vibration.
Small compressors are air-cooled screw chillers but large screw chillers from 30HP and above are only water-cooled screw chillers.
2.2 Screw Chillers
For a study of screw chillers, we must know something about screw compressors.
The screw refrigeration compressor is a kind of rotary refrigeration compressor and has both a piston-type and power type (speed type).
Features of screw compressors:
1. Inhalation process:
The screw-type intake side suction port must be designed so that the compression chamber can fully inhale, and the screw-type air compressor has no intake and exhaust valve groups, and the intake air is only adjusted by opening and closing of a regulating valve.
When the rotor rotates, the space of the groove of the main and auxiliary rotors is the largest when it is turned to the opening of the intake end wall.
At this time, the space of the groove of the rotor communicates with the free air of the intake port, because the groove of the air is exhausted.
The air is exhausted in its entirety. At the end of the exhaust, the groove is in a vacuum state.
When it is turned to the intake port, the outside air is sucked and flows into the groove of the main and auxiliary rotors in the axial direction.
Screw air compressor maintenance reminds us that when the air fills the entire tooth groove, the air intake side ends face of the rotor turns away from the air inlet of the casing, and the air between the tooth grooves is closed.
2. Closure and transportation process:
At the end of the inhalation, the main and auxiliary rotors will be closed with the casing and the casing will be closed.
At this time, the air is not closed in the groove, that is, [closed process].
The two rotors continue to rotate, and the tooth peaks coincide with the groove at the suction end, and the mating surface gradually moves toward the exhaust end.
3. Compression and injection process:
During the conveying process, the engaging surface gradually moves toward the exhaust end, that is, the gap between the engaging surface and the exhaust port gradually decreases, and the gas in the groove is gradually compressed, and the pressure is increased, which is [compression process].
At the same time, the lubricating oil is also injected into the compression chamber and mixed with the chamber gas due to the pressure difference.
4. Exhaust process:
When the meshing end face of the rotor in the maintenance of the screw air compressor is turned into communication with the exhaust of the casing, (the pressure of the compressed gas is the highest), the compressed gas starts to be discharged until the meshing surface of the tooth peak and the groove moves to the exhaust.
End face, at this time, the space between the two rotor meshing surfaces and the casing exhaust port is zero, that is, the completion (exhaust process), at the same time, the length of the groove between the rotor meshing surface and the casing air inlet reaches a long time, the inhalation process is going on.
5. Lubricating oil and capacity adjustment system for screw chiller
The main functions of lubricating oil in screw chiller compressors are lubrication, cooling, and capacity adjustment.
The oil pressure in the piston-cylinder pushes the piston and spool to move forward/backward in the compression chamber.
In particular, the differential pressure oil supply system in the Handbell RC-2 series can eliminate the use of external oil pumps in piston compressors.
However, in some special applications, an external oil pump is still required to ensure the safe operation of the screw chiller.
The bearings in the RC-2 series Hanbell screw compressors only need to provide a small amount of oil for lubrication.
The oil injected into the compression chamber can form an oil film in the compression chamber to increase the efficiency of the compressor and absorb some of the heat generated in the above process.
To separate the lubricating oil mixed from the refrigerant gas, an oil separator is required to ensure that as little oil as possible is carried into the screw chiller refrigeration system.
Pay special attention to the temperature of the lubricant, which is an important factor affecting the life of the compressor bearing.
High lubricating oil temperature will reduce the viscosity of the oil, resulting in a decrease in the lubricating ability and heat absorption capacity of the lubricating oil.
It is recommended to keep the viscosity of the lubricating oil above 10 mm2/s.
The oil temperature should be kept above the system condensation temperature to avoid the migration of refrigerant into the system during the summer.
When the ambient temperature is too low, the viscosity of the lubricating oil is high.
In this case, the pressure drop of the oil passage in the oil passage is too large to be properly loaded, resulting in a heavy load starting of the compressor.
It is recommended to equip the oil heater to heat the oil to increase the oil temperature in a short time.
If the compressor is operating under extreme conditions, an external oil cooler is also required. Have Hanbell determine the amount of cooling required for the oil cooler and the oil flow.
It is recommended to use some lubricating oil with high viscosity under the conditions of severe working conditions.
At this time, the exhaust temperature is higher, which can lower the viscosity of the lubricating oil and ensure the proper viscosity of the lubricating oil.
In addition, there may be a phenomenon in which the amount of oil returned from the evaporator is insufficient, such as a flooded refrigeration system, etc., and oil return is difficult in these systems, resulting in loss of oil in the compressor.
If there is a problem of insufficient oil return in the system, it is recommended to install a secondary oil separator between the compressor venting condenser of the screw chiller to further reduce the oil entering the system.
Precautions:
1. It is recommended to install the optional oil level switch to avoid malfunction of the compressor oil level.
2. The screw compressor can withstand a certain short liquid attack concerning the piston compressor, but the long-term liquid compression affects the viscosity of the lubricating oil, and the bearing lubrication is insufficient, which easily causes the compressor to be stuck.
Screw chiller four-stage capacity adjustment system load status sharing:
25% (33%) load
When the compressor of the screw chiller is started, the solenoid valve is activated and the piston is at the 25% (33%) load position.
In this state, the high-pressure oil coming from the fuel tank is continuously injected into the piston cylinder through the capillary tube, and the high-pressure oil in the piston cylinder is directly bypassed to the suction port.
At this time, all the pistons remain in their initial positions.
Note: The 25% load condition is designed to shorten the start-up time only, avoiding the motor starting current being maintained for a long time and tripping protection.
Do not operate for a long time under the 25% load state after the start-up process. It should be directly loaded and operated (especially under a large differential pressure/pressure ratio) to prevent damage to the rotor, bearings, and other components due to excessive compressor discharge temperature that will affect the screw chiller operation.
50% (66%) load
When the 50%/66% solenoid valve is activated by the temperature control, the power failure is turned off by 25%, and the high-pressure oil coming from the fuel tank flows into the piston cylinder, pushing the piston to the right when moving to 50%/66%.
Since the high-pressure oil is returned from the oil discharge hole through the 50%/66% to the suction port, the piston stops operating at this position, and the compressor of the screw chiller is kept at the load state of 50%/66%.
75% load
AdvantaWhen the screw chiller 75% solenoid valve is activated, the 50% solenoid valve is turned off when the power is turned off, and the high oil pressure pushes the piston to continue to move to the right.
When moving to 75%, the high-pressure oil is returned from the oil discharge hole through 75% to The suction port, so the piston stops running at this position, and the compressor of the screw chiller is kept at 75% load. ge of semi-hermetic screw compressor.
100% load
When we turn off all the solenoid valves of the screw chiller, the high oil pressure continues to flow into the piston cylinder, gradually pushing the piston to the suction side.
When the slide valve contacts the dead center of the compression chamber, the piston also reaches. Its dead center position, at this time there is no phenomenon of bypassing the compressed gas.
At this time, the compressor of the screw chiller reached full load operation.
Spray cooling motor, motor working temperature is low, long life; open compressor uses an air-cooling motor, motor working temperature is high, affecting motor life, screw chiller installation room working environment is poor; using exhaust cooling motor, the motor working temperature is very high, The motor has a short life.
Generally, the external type of oil is large in volume, but the efficiency is high; the built-in oil is combined with the compressor, and the volume is small, so the effect is relatively poor.
The secondary oil splitting effect can reach 99.999%, and the compressor can be well lubricated under various working conditions.
They sit slightly off-center in a shaft, with one side always touching the wall.
As they move at high speeds, they accomplish the same goal as the reciprocating compressor-one part of the shaft is always at a different pressure than the other, so gas can come in at the low-pressure point and exit at the high-pressure point.
The screw compressor has a male and a female rotor. The male rotor drives the female rotor if it is an oil-injected screw compressor technology, and a timing gear drives both rotors in the oil-free compressor technology as both rotors will run harmonically with minimum calculated clearance between both elements.
The basic principle of a screw compressor is as the male and female rotors are rotating in the opposite direction, they draw air in between them.
As the air progresses along with the rotors the air is compressed as the volume space between the rotors decreases, hence creating compressed air that is displaced to the outlet.
2.3Advantages and Disadvantages of Screw Chillers compared to Piston Chillers
Advantages:
1)Less possibility to break down: As the screw compressor has only two moving parts that are not in contact with each other, so there is no wear or tear, and hence it is less possible to break down.
2)Less noise: In a screw compressor, the screws rotate in one direction and thereby causing less noise, heat, and vibration. Furthermore, the screw compressor is skid mounted and therefore foundation is not required.
3)Suitable for continuous operation: For the above reasons, screw compressors are suitable for 24 hours of continuous operation.
4)Energy-saving: More airflow at less power consumed. The difference is more beneficial viable at 20HP and above machines.
5)Compact in size: Screw compressors are smaller in size and lighter in weight and can be installed in a sealed compartment.
6)Resistant to harsh conditions and environment: Taken care of in the right way, this compressor can last around 2 to 5 times longer than the piston compressor.
Disadvantages:
1)Higher Price: Compared to a piston compressor, screw compressors are pricey.
2)Higher lubricant consumption: It has a complicated lubricating system and thus consumes more lubricant.
3)High precision installation requirements: Installation required higher precision and techniques.
Generally, there are 2 types of screw chillers: air-cooled screw chiller and water-cooled screw chiller
Let's have a look at how these two types of screw chiller work and their flow diagram as below:
For air-cooled screw chiller:
The air-cooled screw chiller has a key component as the semi-hermetic screw type compressor, and the air-cooled screw chiller unit is out of the evaporator as a gas refrigerant;
After the screw compressor is adiabatically compressed, it becomes a high temperature and high-pressure state.
The compressed gas refrigerant is condensed by isostatic cooling in a condenser, and after condensation, it is changed into a liquid refrigerant, and then expanded to low pressure through a throttle valve to become a gas-liquid mixture.
The liquid refrigerant under low temperature and low pressure absorbs the heat of the cold matter in the evaporator and becomes a gaseous refrigerant again.
The gaseous refrigerant re-enters the compressor through the pipeline and begins a new cycle. These are the four processes of the refrigeration cycle.
This is also the main working principle of the air-cooled screw chiller.
The evaporator is one of the most important parts in both air-cooled screw chillers and water-cooled screw chillers.
There are 3 types of evaporators or coolers for screw chillers.
1. Dry Shell and Tube Evaporator
The dry evaporator refrigerant passes through the heat exchanger tube, and the cold water runs outside the high-efficiency heat exchange tube.
The heat exchange efficiency of such a heat exchanger is relatively low, and the heat transfer coefficient is only about twice the heat transfer coefficient of the light pipe.
But the advantage is that it is easy to return oil, and the control is relatively simple, and the charging amount of the refrigerant is about 1/2 to 1/3 of the filling amount of the full liquid type unit.
2. Flooded evaporator
The operation of the flooded evaporator and dry evaporator is exactly the opposite.
The cold water passes through the heat exchange tube, the refrigerant completely immerses the heat exchange tube, and absorbs heat, and evaporates outside the heat exchange tube.
There are many needle-shaped holes on the surface of the heat transfer tube of the Flooded evaporator, and there are spiral protrusions on the inner surface of the tube to enhance the heat exchange on the cold waterside.
The high-efficiency heat transfer tube that simultaneously enhances the boiling outside the tube and the heat transfer inside the tube increases the heat transfer coefficient by about 5 times compared with the light tube.
3. Falling film evaporator
Falling film evaporators, also known as spray evaporators, are similar to full liquid evaporators, but they differ from full liquid evaporators.
The refrigerant of the evaporator is sprayed from the upper part of the heat exchanger to the heat exchange tube, and the refrigerant only forms a thin film of cold liquid on the heat exchange tube, so that the refrigerant is reduced in boiling evaporation.
The static liquid level pressure increases the heat exchange efficiency, and the heat exchange efficiency is increased by about 5 times compared with the full flooded screw chiller.
Falling film evaporation is flow boiling. Since the thickness of the liquid film on the outer surface of the tube is small, the boiling point without static pressure increases, and the heat transfer coefficient is high.
The bubbles generated by flooded evaporation (that is, immersed evaporation) tend to accumulate on the surface of the heat exchange tube, resulting in a decrease in heat exchange efficiency, and the heat transfer effect is not as good as that of falling film evaporation.
In general, falling film evaporation is a small temperature difference, but it is necessary to prevent fouling and affect heat transfer efficiency.
In summary: The Flooded type means that the refrigerant is between the copper tube and the shell tube, and the chilled water flows inside the copper tube.
The dry type evaporator is the opposite of the two. The refrigerant evaporates in the copper tube, and the water flows between the copper tube and the shell tube.
They are mainly used for the heat pump air conditioner. In industrial low-temperature chillers, ordinary dry evaporators are generally used.
'Flooded' means that the 'shell-and-tube evaporator' used in the unit adopts the 'flooded evaporator', which is a shell-and-tube evaporator that is different from 'dry' and 'falling-film'.
Its 'shell process' takes the refrigerant cycle, and the 'tube process' takes the chilled water cycle. From the cross-section, it is as if there is a large cylinder of refrigerant in the cylinder, and the water pipe bundle is immersed in the refrigerant.
It is just the opposite of the 'dry evaporator'. The dry type is the 'tube' refrigerant, and the 'shell' water is like the refrigerant tube bundle soaked in the water.
The Flooded evaporator and the flooded screw chiller have higher heat transfer efficiency than the dry evaporator/dry screw chiller unit, and the temperature difference between the outlet water temperature and the evaporation temperature is small, and the resistance along the path is small.
which is suitable for units with large circulation ( For example, the centrifuge), the cooling effect is good. However, refrigerant charge requirements are large and a dedicated oil return system is required to help the compressor return oil.
Advantages and disadvantages of dry and flooded evaporators
The Flooded shell and tube evaporator run water in the tube, and the refrigerant evaporates outside the tube cluster, so the heat transfer surface is basically in contact with the liquid refrigerant.
Generally, the amount of refrigerant charged in the casing is about 55% to 65% of the effective volume of the cylinder, and the refrigerant liquid is heated and vaporized and then returned to the compressor through the liquid separator at the top of the cylinder. Easy operation and management, high heat transfer coefficient.
The disadvantages are:
1 When the evaporation temperature of the refrigeration system is lower than 0 °C, the water in the pipe is easy to freeze and destroy the evaporation pipe.
2 The refrigerant is filled in a large amount
3 Influenced by the height of the refrigerant liquid column, the evaporation temperature at the bottom of the cylinder is high, which will reduce the heat transfer temperature difference
4 The lower part of the evaporator cylinder will accumulate oil, and there must be reliable oil return measures, otherwise, it will affect the safe operation of the system.
The dry shell tube type, that is, the refrigerant of the non-full liquid evaporator flows in the tube, and the water flows outside the tube cluster.
There are usually several processes for refrigerant flow. Due to the gradual gasification of the refrigerant liquid, the higher the flow rate, the more the number of process tubes.
To increase the water side heat exchanger, a plurality of baffles are arranged on the outer side of the tube heat transfer tube, so that the water flows across the tube cluster multiple times.
The advantages are:
1 Lubricating oil enters the compressor with the refrigerant, there is generally no problem of oil accumulation
2 fewer refrigerants are filled, generally only about 1/3 of the full liquid type;
When 3t0 is around 0 °C, the water will not freeze.
However, the use of this evaporator must be noted:
1 There are multiple processes for the refrigerant. If the end cover is not well treated, it will produce effluent, which will make the liquid entering the next process unevenly distributed and affect the heat transfer effect
2 There is a leakage problem on the waterside. Because there is a gap of 1~3mm between the outer edge of the baffle and the casing, and there is a gap of about 2mm between the heat transfer tube, water leakage will occur.
The practice has proved that water leakage will cause the waterside heat transfer coefficient to decrease by 20% to 30%, and the total heat transfer coefficient by 5% to 15%.
4. Features of air-cooled screw chiller:
1. Semi-hermetic screw-type high-efficiency compressor, with single-machine system and dual-machine series selection, the unit is compact in structure and convenient in maintenance; adopts the new 5:6 screw rotor design, stable operation, high efficiency, and energy-saving.
2. Advanced intelligent frosting method. Microcomputer control analyzes the temperature of each point at any time, optimizes the defrost cycle time, and ensures that the defrost does not affect the normal operation of the equipment in time.
3. Professional motor cooling unit. Meet the operating conditions of severe working conditions.
4. With a new generation of high-efficiency heat exchange tubes, the heat transfer coefficient can be increased by 5%.
The double-slot tube-plate design and advanced tube expansion technology make the structure more sealed and reliable, completely avoiding the possibility of mutual penetration.
For water-cooled screw chiller'
When the water-cooled screw chiller is working, the screw compressor draws the low-temperature and low-pressure refrigerant in the evaporator into the cylinder, and the compressor steam is compressed into high-temperature and high-pressure refrigerant, then enters the condenser through the exhaust pipe.
The high temperature and high-pressure refrigerant gas exchanges heat with the cooling water in the condenser, transfers heat to the cooling water, and the refrigerant gas condenses into a high-pressure liquid.
The high-pressure liquid from the condenser is throttled and depressurized by the thermal expansion valve and then enters the evaporator.
In the evaporator, the low-pressure liquid refrigerant absorbs the heat of the chilled water and vaporizes, so that the chilled water is cooled and cooled to become the required low-temperature water.
The vaporized refrigerant gas is again sucked into the compressor for compression and is discharged into the condenser.
So that it is continuously circulated and continuously circulated, thereby achieving cooling of the chilled water.
A water-cooled screw chiller must go along with a cooling tower, water pump, insulation water tank, to make a complete water cooling system.
Efficient semi-hermetic screw compressor, the screw chiller runs smoothly and the noise is low.
Inspiratory cooling results in low motor operating temperatures and long motor life.
With high-quality bearings, the bearing life is at least 40,000 hours. Built-in oil separator for smaller size and better results.
It can be safely implemented in the range of 0% to 100% or stepless energy regulation to maximize power conservation.
The condenser adopts a high-efficiency shell-and-tube heat exchanger (optional stainless steel plate heat exchanger), built-in high-efficiency heat exchange tooth tube, reasonable design, and good heat exchange effect;
The evaporator adopts a high-efficiency shell-and-tube heat exchanger (optional stainless steel plate heat exchanger), built-in high-efficiency heat exchange tooth tube, reasonable design, and good heat exchange effect;
Suitable for R22, R407c, R134a, R404A, and other working fluids.
Less moving parts and low failure rate. An economizer can be selected to further increase compressor refrigeration capacity and efficiency.
A spray chiller can be selected to extend the range of applications for the compressor.
Oil cooling can be selected to increase compressor efficiency and compressor application.
There are advantages of using screw chillers:
1. Screw chiller with simple structure, less moving parts, less wearing parts, only 1/10 of the piston type, low failure rate, and long service life.
2. The circular motion is stable, there is no surge phenomenon during the low load operation, low noise, and low vibration.
3. The compression ratio can be as high as 20 and the EER value is high.
4. Convenient adjustment, the stepless adjustment in the range of 10%~100%, high efficiency in partial load, and significant power saving.
5. Small size, lightweight, can be built as a fully enclosed large capacity screw chiller unit.
6. Not sensitive to wet strokes.
7. It is a positive pressure operation, and there is no problem with the intrusion of outside air.
Screw chillers are widely used both in industrial applications and commercial fields:
1. Screw chiller for industrial application
Screw chillers can provide 5~15°C chilled water, or use ethylene glycol solution as the coolant.
Screw chillers can also provide a -5~+5°C process frozen aqueous solution, which can be used as ice storage, low-temperature air supply, central air conditioning, and other production processes.
At the same time, according to the requirements of the user, TopChiller can specially design the screw chiller to provide a large temperature difference range (the temperature difference between the inlet and outlet water is 8~15°C).
Or higher than the water-cooled screw chiller (outlet water temperature 15 ° C ~ 25 ° C). The cooling capacity is 94KW-KW.
2, medium temperature screw chiller
The outlet water temperature is -5 ° C ~ -45 ° C, using imported semi-closed screw compressor chiller(with economizer); can provide -5 ° C ~ -45 ° C low temperature.
Ethylene glycol solution or brine solution can be used as a cold source for chemical, pharmaceutical, cold storage, an ice rink, and other processes.
The cooling capacity of this kind of screw chiller is 55KW-KW.
3, low-temperature screw chiller
The effluent temperature is -45 ° C ~ -110 ° C, can provide -45 ° C ~ -110 ° C alcohol or calcium chloride aqueous solution chilled water; using a binary stack or ternary cascade screw refrigeration system. High energy efficiency ratio and stable operation.
At the same time, screw chillers can be designed according to the requirements of users, ultra-low temperature type, anti-corrosion type, explosion-proof type special industrial screw type chiller, which can meet the requirements of various industries for process cold source.
Nowadays, the use of screw chillers is seen in many industries. For this screw chiller, which different industries can be used in the application process, to allow users in different industries to choose more for more understanding.
let's take a brief look at some of the screw chiller applications.
First, the construction industry
Screw chillers can be used in some construction industries.
There are many places used in the construction industry.
For example, it can supply chilled water to concrete, and it can change the molecular structure of concrete.
In the process of construction, it is more suitable for use, and its application can also invisibly play a role in the hardness and toughness of concrete, so it is now seen in many construction industries.
The development in this industry will also become larger and larger, and users who have processed in this industry can choose to use this screw chiller.
Second, the food industry
This type of screw chiller can also be used in some food industries.
We all know that after many foods are processed, they need to be packaged, but the food heated by high temperature needs to be cooled when it is put into the package.
The screw chiller can play such a role, allowing the hot food to cool quickly and fit into the bag, so it is still used in this food industry.
Third, Big factory or central air conditioning of HVAC
The cooling capacity of the screw chiller is higher than that of the scroll chiller.
So this screw chiller can be mainly used in chemical plants, ink printing plants, automobile manufacturers or central air conditioning systems, or other large industrial refrigeration.
The above is the application of screw chillers in the construction, food industries, air conditioning for big buildings.
Now with the development of various industries, the application of such screw chillers will gradually increase, and it will become a must in many industries in constant innovation.
In industrial production, mechanical equipment generates heat during operation.
If this heat cannot be dissipated in time, it will affect the normal operation of the equipment as well as the quality and production efficiency of the product.
Another situation is that the processed product needs to reach a certain temperature during processing to be processed normally or to achieve higher yield and production efficiency.
Then the temperature of the processed product must reach the desired temperature before or during processing.
At this time, it's showing the time of the screw chiller
But how to size a suitable screw chiller for your business?
Cooling capacity
Chilled water flow rate
Inlet and outlet water temperature
Understand the volume, weight, specific heat, and density of the equipment parts being cooled or the raw materials for production and processing
.What is the cooling medium?
Air-cooled screw chiller or water-cooled screw chiller?
You can refer to the above points to size a correct screw chiller for your business.
Select a suitable screw chiller for your industry is very important, besides the above information, there are also some other useful tips for your reference:
1. The main control parameters of the screw chiller are the refrigeration performance coefficient, rated cooling capacity, input power, and refrigerant type.
2. The selection of the screw chiller should be considered according to the cooling load and use. For refrigeration systems with long periods of low load operation, a multi-head piston compressor unit or a screw compressor unit should be used for easy adjustment and energy saving.
3. When selecting a screw chiller, priority is given to units with a higher coefficient of performance values. According to statistics, the average screw chiller operating time under 100% load is about 1/4 of the total running time.
The operating time ratios of 100%, 75%, 50%, and 25% of the total operating time were approximately 2.3%, 41.5%, 46.1%, and 10.1%.
Therefore, when selecting a screw chiller, priority should be given to models with a flatter efficiency curve.
At the same time, the adjustment range of the screw chiller load should be considered when designing and selecting. The multi-head screw chiller has excellent partial load performance and can be selected according to actual conditions.
4. When selecting a screw chiller, pay attention to the conditions of the nominal working condition. The actual cooling capacity of a chiller is related to the following factors:
a) cold water effluent temperature and flow rate;
b) Inlet water temperature, flow rate, and fouling coefficient of cooling water.
5. When selecting a screw chiller, pay attention to the normal working range of the unit, mainly because the current limit of the main motor is the current value of the shaft power under nominal conditions.
6. In the design selection, screw chillers should be noted that under nominal operating conditions, the outlet temperature of cold water should not exceed 15 °C, and the outdoor dry bulb temperature of air-cooled screw units should not exceed 43 °C.
If it is necessary to exceed the above range, it should be understood whether the range of use of the compressor is allowed and whether the power of the main motor is sufficient.
There is another important tip for using a screw chiller- the refrigeration oil or lubrication oil for screw compressors.
Refrigerated oil plays a very important role in the operation of the screw chiller refrigeration system.
Purpose of using refrigeration oil or lubrication oil:
1, Reduce Friction
The injection of lubricating oil forms an oil film on each friction surface of the screw compressor, which reduces friction and reduces energy consumption.
2, Take Away Frictional Heat
Injecting lubricating oil can take away frictional heat, keep the temperature of the moving pair within a reasonable range, and also take away various mechanical impurities to prevent rust and cleaning.
3, Reduce Leakage
Filling the friction surface gap with lubricating oil can seal the friction surface of the refrigeration compressor
Classifications of refrigeration oil or lubrication oil:
1. Natural mineral oil (referred to as mineral oil)
Mineral oil is a lubricating oil extracted from petroleum. It can only be dissolved with weakly polar or non-polar refrigerants;
Mineral oil is divided into four varieties: L-DRA/A, L-DRA/B, L-DRB/A, and L-DRB/B;
2, synthetic oil (referred to as synthetic oil)
Synthetic oil makes up for the shortage of mineral oil, usually has strong polarity, and can be dissolved in a more polar refrigerant (such as R134a);
3. There are two main types of synthetic oils.
Polyester oil: Multi-polyester (POE) oil has a better comprehensive performance
Polyether oil: Epoxy acetylene-propylene oxide polyether (PAG) has a better comprehensive performance
TopChiller is a professional screw chiller manufacturer with decades years of experience.
We have installed thousands of various screw chillers in Singapore, Australia, Indonesia, Nigeria, Saudi Arabia, Kuwait for different industrial and commercial applications.
We also have an after-sales team that can do installation and commission at the screw chiller project site.
After installation, our engineer will give your staff a full detailed training on how to use the screw chiller and maintenance guide.
For the use of screw chillers, some common fault problems include high voltage fault, low voltage fault, low valve temperature fault, compressor overheat fault, communication fault, etc.,
But to effectively solve these fault problems, you must first link the main working principle of the screw chiller, and among them, the four processes of the refrigeration cycle, after the adiabatic compression of the compressor, becomes a high temperature and high-pressure state.
The compressed gas refrigerant is condensed by isostatic cooling in a condenser, and after condensation, it is changed into a liquid refrigerant, and then expanded to low pressure through a throttle valve to become a gas-liquid mixture.
The liquid refrigerant under low temperature and low pressure absorbs the heat of the cold matter in the evaporator and becomes a gaseous refrigerant again.
The gaseous refrigerant re-enters the compressor through the pipeline and begins a new cycle.
After understanding the main working principle of the screw chiller, the common faults of the screw chiller are analyzed below.
1. High-Pressure Alarm
The compressor discharge pressure is too high, causing the high voltage protection relay to operate. The screw compressor from chiller discharge pressure reflects the condensing pressure.
The normal value should be 1.40~1.60MPa, and the protection value should be set to 2.00MPa.
If the long-term pressure is too high, it will lead to an excessive operating current of the compressor, easy to burn the motor, and easily cause damage to the valve port of the compressor exhaust port.
What should be done is to control the discharge pressure of the compressor in a safe range.
2. Low-pressure alarm
The screw compressor suction pressure is too low, causing the low voltage protection relay to operate. The suction pressure of the compressor reflects the evaporation pressure.
The normal value should be 0.40~0.60MPa, and the protection value should be set to 0.20MPa. If the suction pressure is low, the amount of return air is small, the cooling capacity is insufficient, and the electric energy is wasted.
The heat of the compressor motor for return air cooling is poor, and the motor is easily damaged! The solution is the same as the high-pressure fault, try to keep the compressor within the normal pressure range.
3. Low valve temperature error
The outlet temperature of the expansion valve reflects the evaporation temperature, which is a factor affecting the heat exchange.
Generally, it has a temperature difference of 5.0 to 6.0 °C from the outlet water of the refrigerant water. When a low valve temperature fault occurs, the compressor will stop.
When the valve temperature rises, it will automatically resume operation with a protection value of -2.0 °C.
4. Compressor overheat fault
A thermistor is embedded in the winding of the compressor motor, and the resistance is generally 1kΩ. When the winding is overheated, the resistance value will increase rapidly.
When the winding exceeds 141kΩ, the thermal protection module SSM will act to cut off the unit operation and display the overheat fault. The TH fault indicator lights.
5. Communication failure
The control of each module by the computer controller is realized through the communication line and the total interface board.
The main cause of the communication failure is the poor contact or open circuit of the communication line, especially the interface is affected by moisture oxidation, and the unit electronic board or the total interface.
If the board is faulty, the address dial switch is improperly selected, and the power failure can cause a communication failure.
The above five kinds of fault phenomena are the most common, and understanding these fault phenomena and judgment ability and solution has an irreplaceable effect on extending the service life of the screw chiller.
Besides the above, we must point the screw compressor out. Because the screw compressor is the key refrigeration part for a screw chiller.
The screw compressor has the characteristics of small size, lightweight, and easy maintenance, and is a type of development that is faster in refrigeration compressors.
On the one hand, the screw line and structural design have made great progress.
On the other hand, the introduction of special milling machines for screw rotors, especially grinding machines, has improved the machining accuracy and machining efficiency of these key components, and the performance of screw compressors has been effectively improved.
Due to the continuous improvement of the working reliability of the screw compressor, it has gradually replaced the reciprocating compressor in the medium cooling capacity range and occupied part of the market of centrifugal compressors.
In operation, there are a lot of operational details to be aware of to ensure the smooth and efficient operation of the equipment and improve production efficiency.
Screw compressor can't be running
Electrical fault:
First check if the power supply wiring of the compressor is correct, whether the power switch is properly closed, whether the power fuse is blown, and whether the power supply voltage reaches 90% or more of the rated voltage.
Check the compressor's pressure relay components for damage and pressure regulator settings.
Poor contact of the start button, this situation is less common, because the current screw compressor, unless it is cheap to buy a very low-cost machine, it is generally not a problem, even if it is solved, it is very simple.
Operation failure:
At the time of starting, the pressure of the outlet switch and the outlet is not set too high, the switch of the electrical circuit is not restored, and the setting of voltage and current is unreasonable.
The general screw compressors have automatic protection devices, so when some parts of them fail, they cannot be started normally. Start and stop the control loop.
Because there are many electrical components, there are more control points and the failure rate is relatively high. Start button, stop button or switch, etc., may cause the host to fail to start or stop due to improper operation.
Such as the start button, stop button, emergency stop button, control panel, etc., excessive force during operation may cause the button to be stuck on the edge of the button housing and cannot be reset.
Screw chiller failure:
Mainly including compressor motor failure, rotor lock, and so on.
When the compressor is overloaded for a long time, it will form a rotor tooth surface and the bearing fatigue damage will be stuck; the compressor lubricating oil pipeline will be blocked to form a lack of oil, causing the anode and the anode and the bearing temperature to be too high and damaged and locked.
If the bearing and the male and female rotors are disassembled when repairing the compressor, the installation is not cautious and the installation accuracy is not up to the requirement. The anode and the anode are not parallel and the male and female rotors cannot be rolled.
In addition, when the compressor is repaired improperly, an external solution is applied to the rotor, and the axial and radial gaps between the female and male rotors are changed so that they cannot rotate.
Under normal circumstances, the manufacturer has set parameters such as lubricant level, oil pressure, and filter pressure difference on the compressor control system.
If the above conditions occur, it will stop actively to protect the compressor.
However, some users tend to increase the set parameters or short-circuit certain alarm lines and pipelines for convenience and save money, causing the equipment to leave the monitoring and causing the failure.
Generally, the probability of motor failure in the compressor is relatively low, but if it occurs, it will be more troublesome, and it needs to be excluded and repaired by professionals.
Screw Compressor Exhaust pressure is too low
Under normal circumstances, the in-service compressor can eliminate the exhaust pressure caused by the high altitude, but can not ignore the increase in gas consumption.
If there is no large leak point in the compressed airline, it is a problem with the compressor unit itself. We can check if there are any problems with the following aspects:
1. Is your screw chiller maintenance timely?
The displacement of the compressor drops. First, see if the compressor has been serviced? Many times, the displacement of the compressor drops, there is no big problem, that is, the customer is neglected to maintain.
If the working environment is not ideal, the compressor air filter is easy to block. Lighter can use dust to remove dust; blockage is serious, need to replace the new air filter.
2. Are the intake valves all open?
The compressor discharge is reduced, check the unit, if just maintenance, remove the three filters and oil problems, then first check the compressor intake valve.
Remove the air intake hose, turn on the compressor, and see if the opening of the intake valve is normal. The theoretical design life of the intake valve is 100,000 times.
Because each manufacturer uses different brand batches, the quality is also different. Therefore, the failure of the intake valve may cause the unit to reduce the exhaust volume.
If the intake valve cannot be fully opened when the compressor is loaded, it can be concluded that the exhaust gas volume is a failure of the intake valve and should be removed for repair or replacement.
3. Motor failure
After the intake valve failure is removed, if the screw chiller exhaust volume has not changed, consider whether the motor is faulty.
Due to a local short circuit in the motor coil, or bearing wear, the motor shaft wears, causing the motor speed to be lower than the rated speed, causing the compressor to discharge.
The motor coil, bearing, etc. should be repaired, and the compressor displacement should be tested after repair'
Closer to this principle is the belt-driven compressor, which should take into account the belt load and the intact state.
Sometimes the belt speed is insufficient due to the slip or slack of the belt, resulting in low exhaust pressure.
4. Pressure switch setting working pressure is too low
This kind of situation is often caused by changes in working conditions, or after the system has been adjusted, overhauled, etc., the system parameters are moved.
Otherwise, under normal circumstances, the working pressure will not be easily mishandled after being set.
Screw Compressor parameter setting is not recommended by the user at will but should be combined with the equipment supplier and the user to comprehensively consider the working conditions and equipment operating characteristics, and set a reasonable value.
Compressor Exhaust oil content is too high
For companies that are very concerned about air quality, the air must contain too much oil. There are many reasons for this problem, mainly due to the following reasons:
first, the oil level is too high;
second, the return pipe filter or orifice is blocked;
the third is that the oil and gas separation core is damaged.
The fourth is that the gas pressure of the compressor is too low; then the minimum pressure valve fails; the last is the problem of the lubricant itself.
If too much foam is used, it will also increase the oil content of the gas.
1. Too much cooling oil added to the compressor
An excessive amount of lubricating oil is added, which exceeds the allowable range.
Although the separation system separates the oil and gas during the operation of the compressor, in the discharge of the gas, the gas also entrains the cooling oil into the gas, causing the discharge. The oil content in the gas is too high.
2. The return line is faulty
In the working process of the screw compressor, the oil return pipeline shoulders an important responsibility.
The oil separation inside and the compressor inlet will form a pressure difference. Under this pressure difference, the oil return pipeline is responsible for the oil separator.
The oil collected at the bottom is sent back to the compressor and continues to be used during the next compression cycle.
If there is a fault such as a blockage, breakage, and incorrect installation on the return line, the oil collected at the bottom of the oil separator cannot be sent back to the compressor, causing too much oil to accumulate at the bottom, and this part of the oil that is not sent back to the compressor is As the gas is discharged, there is a phenomenon of oil in the exhaust process.
3. Oil separation core is damaged
During the operation of the screw compressor, if the oil separation core is damaged, such as damage or perforation, it loses the role of oil and gas separation.
That is to say, the exhaust gas of the mixed gas and the compressor is directly penetrated, and a large amount of cooling oil is not separated, and as the gas is discharged together with the body, an oil failure occurs during the exhausting process.
4. Screw chiller system pressure control is too low
If the system pressure control is too low, the centrifugal force in the separator will be less than the centrifugal force required for the work, then the function of the separator will not be fully reflected, resulting in the oil content in the separator entering the next step is too high, beyond its separation range.
As a result, the oil and gas separation is not complete, and oil failure occurs during the compressor exhaust process.
5. Minimum pressure valve failure
During the operation of the screw compressor, the function of the minimum pressure valve is to ensure that the system pressure is controlled above the minimum pressure during operation.
If the minimum pressure valve fails, the minimum pressure of the system will not be guaranteed. Since the gas consumption of the luck equipment is very large, the system pressure is too low, and the oil return pipeline cannot return oil.
The oil that collects at the bottom of the oil separator will not be returned to the compressor and will expel the compressor with the compressed gas, causing oil failure during the exhaust process.
6. The quality of the cooling oil is unqualified
If the compressor is added with a relatively poor defoaming lubricant, or the ambient air humidity is high, the water leakage at the bottom of the lubricating oil station will cause the lubricating oil to foam, causing the oil content in the exhaust gas to increase.
Compressor Exhaust temperature is too high
Mechanical failures include:
a. oil stop valve failure;
b. compressor oil filter failure;
c. thermal control valve (temperature control valve) malfunction;
d. compressor oil regulator abnormal;
e. compressor oil cooler Abnormal (this fault is common in water-cooled compressors);
f. Compressor head failure, including poor lubrication and unreasonable design of the machine itself, installation is not necessary;
g. air filter failure; h. oil and gas separator failure; i. Temperature sensor and computer failure, abnormal reading.
The effects of compressor oil include:
a. insufficient compressor oil;
b. deterioration of compressor oil, poor fluidity of oil, reduced heat exchange capacity;
c. improper selection of compressor oil viscosity;
d. The quality is not good: the thermal oxidation performance is poor, the viscosity-temperature performance is poor, and the air separation ability is poor.
The screw compressor cannot be unloaded
Loading and unloading are the basic functions of the compressor. They cannot be loaded and unloaded, and the compressor is useless.
Because if it can't be loaded, the compressor has no compressed air output; if it can't be unloaded, after there is no compressed air demand downstream, it can be imagined as: 'The consequence of constantly inflating a balloon.'
When the compressor exceeds the rated pressure during operation, it will continue to load and run, and the maximum pressure value will be set to cause the screw compressor to trip or the safety valve will act.
If the actual air consumption of the production is not greater than the gas volume of the compressor unit and a large amount of leakage of the pipeline, the compressor may not be unloaded mainly for the following reasons:
a. If the pressure switch is set improperly or after setting, there will be elegant and false, and the false number will be reported.
b. The intake valve is not working properly, the card is stuck, etc.;
c. When the system stops using the gas, the venting solenoid valve is invalid, and the performance state is the pressure slowly. Rise, not like loading up;
d. control loop failure;
e. loading solenoid valve failure, such as loading at the same time of unloading, and the loaded gas volume is greater than the unloading, so the pressure continues to increase.
In the current screw compressor design and production level, many of the problems with screw compressors are mostly caused by untimely maintenance or improper operation.
If we strictly abide by the screw chiller operation process and pay attention to screw chiller maintenance, then I believe that many unnecessary failures will not happen.
Screw chiller selection points
1. The main control parameters of the screw chiller are the refrigeration performance coefficient, rated cooling capacity, input power, and refrigerant type.
2. The selection of screw chillers should be considered according to the cooling load and use. For refrigeration systems with long periods of low load operation, a multi-head piston compressor unit or a screw compressor unit should be used for easy adjustment and energy saving.
3. When selecting a screw chiller, priority is given to units with higher performance coefficient values.
According to statistics, the average screw chiller operating time under 100% load is about 1/4 of the total running time. 100%, 75%, 50%, 25% of the total running time
The operating time ratio of the load is approximately 2.3%, 41.5%, 46.1%, and 10.1%. Therefore, when selecting a correct screw chiller, priority should be given to models with a flatter efficiency curve.
At the same time, the adjustment range of the screw chiller load should be considered when designing and selecting.
The multi-head screw chiller has excellent partial load performance and can be selected according to actual conditions.
4. When selecting a suitable screw chiller, pay attention to the conditions of the nominal working condition. The actual cooling capacity of a chiller is related to the following factors:
a) cold water effluent temperature and flow rate;
b) Inlet water temperature, flow rate, and fouling coefficient of cooling water.
5. When selecting a proper screw chiller, pay attention to the normal working range of the model unit, mainly because the current limit of the main motor is the current value of the shaft power under nominal conditions.
6. In the design selection, it should be noted that under the nominal working condition flow, the outlet temperature of cold water should not exceed 15 °C, and the outdoor dry bulb temperature of the air-cooled unit should not exceed 43 °C.
If it is necessary to exceed the above range, the compressor should be known. Whether the range of use is allowed, and whether the power of the main motor is sufficient.
The control of each module by the computer controller is realized through the communication line and the total interface board.
The main cause of the communication failure is the poor contact or open circuit of the communication line, especially the interface is affected by moisture oxidation, and the unit electronic board or the total interface If the board is faulty, the address dial switch is improperly selected, and the power failure can cause a communication failure.
Causes and treatment of abnormal vibration of the screw chiller unit?
The reasons for the insufficient cooling capacity of the screw chiller and the treatment methods?
Reasons for the abnormal sound of the screw chiller during operation and treatment
Causes and treatment of screw chiller exhaust temperature or oil temperature drop?
The reason for and treatment of the screw chiller slide valve movement are not flexible or not working?
The reason for and treatment of the screw compressor body temperature are too high?
Why is the compressor reversing when the screw compressor is stopped?
How to arrange large, medium, and small repairs or maintenance of screw chillers?
Preparation before the starting of the screw chiller:
The correct commissioning of the screw chiller is an important part of ensuring the normal operation of your screw chiller, saving energy and prolonging the service life.
For on-site installation of large and medium-sized screw chiller, the requirements should be familiar with the layout and connection of the entire system, the outline structure and component performance of each equipment, as well as the electronic control system and water supply system.
To this end, engineers such as refrigeration and hydropower should participate in the commissioning.
Users should carefully read the operation manual of the screw chiller provided by the factory before commissioning, and proceed step by step according to the operation requirements.
The operator must undergo special training from the factory to obtain the operation certificate of the screw chiller before the operation can be carried out, to avoid fatal damage to the screw chiller unit caused by the wrong operation.
A Preparation before screw chiller commissioning
(1) Since the screw chiller is medium and large, it is necessary to closely cooperate with the design, installation, and use during commissioning.
To ensure that the commissioning work is carried out in an orderly manner, the relevant personnel must form a temporary commissioning team to fully conduct the commissioning work.
(2) The personnel responsible for commissioning should be fully familiar with the structure and performance of the screw chiller, familiar with the safety technology of the screw chiller, clarify the methods, steps and technical requirements to be debugged, formulate detailed and specific commissioning plans and make each post the commissioning staff clarifies their tasks and requirements.
(3) Check whether the installation of the screw chiller meets the technical requirements, whether the foundation of the screw chiller meets the requirements, and whether the size, specification, and material of the connecting pipeline meet the design requirements.
(4) The power supply system of the screw chiller should be fully installed and commissioned.
(5) Pass the water test on the cold water and cooling water system separately, flush the dirt of the waterway system, the water pump should work normally, and the circulating water volume meets the requirements of working conditions.
(6) Clean and debug the environmental site to achieve clean, bright, and smooth.
(7) Prepare the various common and specialized tools required for commissioning.
(8) Prepare various measuring instruments and meters for pressure, temperature, flow, quality, time, etc. required for commissioning.
(9) Prepare the safety protection equipment necessary for commissioning operation.
B screw chiller commissioning
(1) Charge of refrigerant.
At present, the screw chiller is generally filled with refrigerant before leaving the factory.
After the installation on-site, if no accidental damage is found in the visual inspection, the relevant valve can be opened directly (you should read the manufacturer's instruction manual first, in transit, on the unit).
The valve is normally in the off state for commissioning.
If the refrigerant has been leaked or insufficient, first find the leak point and eliminate the leak, then add the required grade of refrigerant according to the product instruction manual.
Note that the refrigerant charge should meet the technical requirements.
(2) Some users are charged with refrigerant on site, and the refrigerant charge and refrigerant grade must be following regulations.
The refrigerant charge is insufficient. This Will result in insufficient cooling.
An excessive refrigerant charge will not only increase the cost but also adversely affect the operating energy consumption.
(3) Before charging the refrigerant, sufficient refrigerant should be prepared in advance. When filling, it can be directly charged from the special filling valve.
Since the system is in a vacuum state, the pressure difference between the refrigerant and the system in the cylinder is large.
When the valve is opened (the air in the connecting pipe should be blown out with the refrigerant first, so that the air does not enter the screw chiller unit and affect the performance of the unit), the refrigerant is quickly replaced by the cylinder.
In the flow system, after filling, the liquid filling valve should be closed first, and then the connecting pipe should be removed.
Screw chiller starting up and operation
Monitoring and adjustment of screw chiller operation
For screw chillers, the following should be mainly concerned during operation:
1. The temperature and pressure of the chilled water inlet and outlet of the evaporator.
2. The temperature and pressure of the condenser cooling water inlet and outlet.
3. The pressure and temperature of the refrigerant in the evaporator.
4. The pressure and temperature of the refrigerant in the condenser.
5. Electrical current and voltage of the main motor.
6. The pressure and temperature of the lubricant.
7. Is your screw chiller running smoothly, is there any abnormal noise?
8. Whether the valves of the screw chiller have leaks.
9. Is the joint with each water pipe tight?
From the above, the most important is the Danfoss expansion valve adjustment.
Here are some tips for you on how to adjust the thermal expansion valve of your screw chillers:
1. The evaporator outlet should use the thermometer to measure the temperature or look at the suction pressure to check the superheat.
2. Danfoss expansion valve adjustment superheat is too small (supply volume is too large), the adjustment rod should be rotated clockwise half a circle or a circle (ie increase the spring force, reduce the valve opening), increase the degree of superheat, so that Reduced refrigerant flow;
The number of turns of the adjusting rod thread at one time should not be too much (the adjusting rod thread rotates one turn, and the superheat degree changes about 1-2°).
For the same reason, reduce the superheat degree counterclockwise and increase the cooling capacity.
3. Danfoss expansion valve adjustment experience:
Turn the adjusting rod thread to change the opening of the valve so that the evaporator can just be frosted or dew on the outside of the return pipe.
For a screw chiller with an evaporation temperature lower than 0 degrees, if it is touched by hand after frosting, there is a feeling of coldness that sticks the hand, and the opening degree is appropriate; for the evaporation temperature above 0 degrees, the condensation is visible. The judgment of the situation.
4. The correct commissioning of the Danfoss expansion valve directly affects the cooling effect and energy saving of the cold storage.
The cooling of the cold storage is slow, mostly the improper adjustment of the Danfoss expansion valve.
According to the thermal properties of the refrigerant, the lower the pressure, the lower the corresponding temperature; the higher the pressure, the higher the corresponding temperature. Among them, the adjustment of the Danfoss expansion valve is the most critical.
The opening degree of the Danfoss expansion valve is small, the flow rate of the refrigerant is low, and the pressure is low; the opening degree of the Danfoss expansion valve is large, the flow rate of the refrigerant is high, and the pressure is high.
If the expansion valve outlet pressure is too low, the corresponding evaporation pressure and temperature are too low.
However, due to the decrease in the flow rate into the evaporator, the pressure is reduced, the evaporation rate is slowed down, the cooling capacity per unit volume (time) is decreased, and the cooling efficiency is lowered.
Conversely, if the expansion valve outlet pressure is too high, the corresponding evaporation pressure and temperature are too high.
The flow rate and pressure entering the evaporator are increased.
Because the liquid evaporates excessively, the excessive moisture (or even liquid) is sucked by the compressor, causing the wet stroke (liquid blow) of the compressor, causing the compressor to fail to work normally, resulting in a series of work.
Bad conditions, even damage the screw compressor for your screw chiller.
Therefore, the opening degree of the expansion valve should be adjusted according to the current water temperature, that is, adjusted under the pressure corresponding to the water temperature.
The expansion valve must be carefully and patiently adjusted. The pressure must be transferred to the pressure gauge after passing through the evaporator to the water temperature for boiling exchange (evaporation) and then entering the compressor suction chamber through the pipeline. It takes time.
Each time the expansion valve is mobilized, it usually takes 10~15 minutes to stabilize the adjustment pressure of the expansion valve on the suction pressure gauge, and the adjustment cannot be rushed.
The suction pressure of the compressor is the main parameter for adjusting the pressure of the expansion valve.
It is usually prone to failures such as clogging of the filter, leakage of the temperature-sensitive agent, and the like.
The adjustment reaction is not sensitive, the adjustment is out of control or cannot be adjusted.
When the frost is formed at the inlet of the expansion valve (or the valve cover is also frosted), the temperature of the inlet pipe is lower than normal temperature, or even condensation;
The suction pressure of the compressor is lower than the corresponding pressure at the storage temperature, the screw chiller operating temperature and the exhaust temperature is high.
And the cooling temperature drops slowly or can not be lowered, mostly due to the filter plugging of the expansion valve or the dirty plugging failure.
As a leader in screw chiller manufacturing, TopChiller has 20 years of experience in design and making screw chillers.
We have a complete of screw chiller models and cooling capacity from 50Ton to 100Ton-150Ton-200Ton can even up to 300Ton and 500Ton Max.
Both air-cooled screw chiller and water-cooled screw chiller manufactured by TopChiller are featuring precision workmanship, compact design, and high cooling efficiency.
All the refrigeration major components from screw chiller designed by TopChiller are world-first refrigeration brands.
We are willing to provide technical support to all clients, we have both standard and custom designs in air-cooled screw chillers and water-cooled screw chillers.
If you are looking for a reliable screw chiller manufacturer?
If you are searching for a high-quality screw chiller for your business?
Contact our refrigeration engineering to help you get a suitable screw chiller design and solution.
Screw Chiller is the most valuable equipment for industrial application. It is very effective in providing cooling for large Industrial applications.
The rapid increase in Industrialization needs a proper mechanism to run.
When you are seeking a Screw Chiller, You are not only providing a cooling agent to your application but also increasing its efficiency of production.
The Screw Chiller is well equipped with components that help it to run smoothly. It has a decent fabricated quality which shields it from being harmed by the external climate.
It has cost-efficient nature which saves your money and time.
This guide includes every possible piece of information about Screw Chiller to help you select one.
Screw Chiller is an effective heat-removing source that provides cooling solutions to the industrial process and other essential applications.
Providing efficiency and using less power are the core features of a Screw Chiller.
The Screw Chiller uses the two spinning helical screws that provide the required pressure to start the vapor compression refrigerant process.
Due to the presence of a Screw Compressor, it is called Screw Chiller
The refrigerant involves the cooling of the Solution or water.
For safety, it has a high and low voltage protector in case of any sudden increase and decrease in Voltage.
It consists of soundproof because it contains limited parts, which reduces overall sound production. It has a compact structure and is lightweight.
The cool water is circulating the application with the help of a Screw Chiller to keep the application cool.
After Circulating cool water in the application, it becomes hot. After that, the all-over heat is accumulated from the application in Screw Chiller and exited in the atmosphere.
The Screw Chiller is made up of a 50 centigrade environment. The centigrade varies from size to size.
The Size starts from 175 KW t0 KW.
There are also other options of cooling but these are inefficient and cost a lot. The Screw Chiller is manufactured by experts to meet the needs with quality standards at a low cost.
Due to its quality standard, Screw Chiller keeps working 24 hours without the delay and getting heated up.
Screw Chiller Designed by TopChiller
The Screw Chiller is equipped with various features mentioned below.
The evaporator and condenser in it are installed inside the Screw Chiller which saves additional space.
If you want to learn more, please visit our website Screw Type Chiller Unit.
The other machines need a specified foundation for stability as these to vibrate a lot.
Due to the compact size and stability, the Screw Chiller produces a very low amount of vibration. So it can be placed on a normal foundation.
In a high-rise building, the cost of the pump lift reduces to a great extent.
The highest ambient temperature is 50 Centigrade, this decreases its failure on summer days.
As mentioned above the Screw Chiller has few parts so, it takes less time to be installed as compared to its alternative.
The Screw Chiller is equipped with many features like simple design, flexible adjustment, fewer wearing parts, and it has a low failure rate.
The Screw Chiller has no suction and exhaust valve. Suction is a negative difference in the pressure produced among two points which change either liquid or gas from higher pressure to lower pressure.
When the heat pump unit is working the pressure in working condition will be more. At that point, the Screw Chiller is a suitable system.
One of the key features is that it uses multiple refrigeration circuits.
Multiple compressors have a cycle control to start and stop which helps in balancing the load and increasing the load.
If any of the circuits are out of order and need maintenance, so another circuit of Screw Chiller normally works as a backup.
Screw Chiller is equipped with environmental protection and energy-saving features.
With the help of Artificial intelligence, it adjusts its capacity according to the need to save energy and save the environment from contaminating particles in heat.
There are four main components of the Screw Chiller are Compressor, evaporator, expansion valve, and controls.
Every system has the same components. However, they work differently in every system.
Compressor
Screw Chiller has a unique compressor. Its compressor uses spiral rotators that help in compressing the gas.
The Compressor rotates the refrigerant from lower pressure to higher pressure. The compressor can provide a medium load for a medium application.
The compressor is situated in the stationary casing of the Screw Chiller.
Evaporator
The evaporator in Screw Chiller is considered a heat exchanger. The evaporator removes unnecessary heat from the liquid and exits the heat in the environment.
When the heat exits through evaporate the water becomes cool. The water then travels back to the application to provide cooling.
The Screw Chiller evaporator is often insulated. It is insulated because the cool water is expensive to produce.
If there will be no cover or insulation on the evaporator of the Screw Chiller then it might collect heat from the room where it is located instead of the plant.
In this way, the cool water will be heated again even without circulating in the application.
Insulating is covered to prevent unnecessary heating from the room.
Expansion Valve
The expansion valve has a very important role. This helps in controlling the flow of refrigerants to the refrigeration.
The expansion valve is used to change the liquid refrigerant with high pressure in the condenser to the gas refrigerant with low pressure in an evaporator.
In Screw Chiller the flow rate is controlled by an expansion valve to get the desired cooling load for application.
Controls:
The Screw Chiller has the necessary controls. Like controlling its cooling capacity. Controlling the flow rate of the liquid.
It has a control system that indicates if there is any fault. It rings an alarm when anything in it goes wrong.
It has the feature of working on the set cooling temperature. You can set the required temperature on the control system.
Screw Chiller Unique Compressor
Everyone wants a cost-efficient Screw Chiller. However, the initial investment might be expensive.
Although it is cost-efficient for the long term as you do not have to buy different individual systems. The applications already cost a lot.
The Screw Chiller in application reduces the power consumption cost up to 30%. It does not need a high power supply. It works in normal voltages too but power must be stable
The application might be the only thing in the plant that consumes more power and it is logical to seek the low-cost efficient Screw Chiller.
To analyze the actual cost efficiency you should consider two factors that affect the consumption of power.
The first factor is the load. The Screw Chiller work according to the load of the application. If the load of the application is high then it may consume high power.
The second factor that affects its power consumption is the temperature of water traveling to the condenser.
When the temperature of the water is high then the Screw Chiller has to work more effectively and it will require more energy, vice-versa.
The Screw chiller with the constant-speed compressor motor lowers the entering of water into the condenser by closing its promotional vanes which saves energy.
The speed of the Screw Chiller also increases and reduces costs.
However, lowering condenser water temperature also lowers the cost. The cost also depends on the size and working of your application.
If your application works 24/7 so as the Screw Chiller then you might expect more energy consumption.
Every application needs a cooling agent. More often it's up to the consumer to choose a cooling system according to their needs.
It is mostly centralized which means one Screw Chiller serves to cool everywhere it needs. It consumes less power when it is centralized.
The other systems are decentralized, these works individually and may result in high power consumption.
It also brings down the temperature of the liquid in laboratories of nuclear facilities.
More often in during plastic production, the heat is produced in excess during injecting and molding process. It Works efficiently if there is any excess heat in the application.
If the heat is not removed at the required time your application will cease to work.
If you have any application related to food then Screw Chiller is a must for you. As it keeps, meat, dairy farm products, food packages, and beverages cool.
It has an effective mechanism and system. It is easy to use due to its user-friendly control system. It works quietly and does not produce an irritating sound.
However, instead of its user Friendly, the Screw Chiller must be operated under the supervision of a highly professional person.
There is a water-cooled Screw Chiller, these use cooling towers and send water according to needs.
The water-cooled Screw Chiller is perfect for indoor installation and where a source of water is convenient. It can work under a temperature of 50°C.
If the area is water scarce and it is harder to obtain water in high quantity. So, it is better to install an air-cooled Screw Chiller.
An air-cooled Screw Chiller is installed outdoor. As these release heat in the atmosphere.
Screw Chiller is Widely used for Nuclear Facilities
The increasing technologies have created a demand for advanced HVAC systems and powerful Screw Chiller.
Everyone seeks a bunch of advantages while selecting any HVAC system.
The Screw Chiller is the right choice for the most advanced applications. It has many benefits as mentioned below.
Its pipes and the transporter of water occupies less space.
It has very few electronic boxes and these do not consume more space.
It does not over-cool the application as this affects the production.
Screw Chiller has the feature of adjusting load starting from the load like 100%, 75%, 50%, and 25%.
Its mechanism uses water as the source of coolant and has higher efficiency as compared to the water-cooled Screw chiller.
This saves a colossal amount of energy and is not sensitive to wet stroke.
The water inside its Compressor reduces the vibration of the application.
Whether it's long run or short run its natural mechanism does not produce any sound.
The motor of the Screw Chiller also works quietly to prevent sound production.
The motor also prevents the sound of the Compressor to come outside.
The mechanical system of the Screw Chiller also does not require high-cost maintenance.
However, a regular check-up after intervals is necessary.
Its mechanism has long pipes that are stretched to a great area of application.
The usage of pipe saves the space for application and it is feasible to connect the entire System.
The long-run compressor is installed that never causes trouble and works without any disturbance.
You don't need to worry about shifting the Screw Chiller while shifting the whole plant.
It is flexible and customizable to adjust where it works perfectly.
Screw Chiller Shifting
These both are used for providing cooling to industrial applications.
Screw Chiller:
Centrifugal Chiller:
The centrifugal Chiller generally produces the sound of 80DB and its noise is higher than Screw Chiller.
Centrifugal Chiller
The Screw Chiller work in several steps, which include the working of its all components simultaneously.
Step 1:
The state of the Screw Chiller is gas refrigerant after the compressor is compressed it turns into high pressure and high-temperature state.
The compressed gas refrigerant is cooled down and condensed in the condenser under constant pressure.
After the process of Condensation, the gas refrigerant changes into a liquid refrigerant.
Step 2:
Then liquid refrigerant is expanded to the low pressure through an expansion valve. Then it becomes a mixture of gas and liquid.
Then the liquid absorbs the heat under low temperature and pressure. The liquid is to be cooled in an evaporator after the removal of heat.
Step 3:
After cooling, the refrigerant turns into a gas again. The gas state of the refrigerant travels to the compressor and restarts the cycle again.
Screw Chiller Working
Also, consider the flow rate of your system. Right flow rate with right temperature increases overall production.
The size of the Screw Chiller varies. Its size depends on the load of the plant.
Never select the undersize one. The undersize has many problems including unstable temperature and inefficient performance.
Its oversize also makes it inefficient. To select the right size it is better to consult with the experts.
There is E-calculator available on the internet that helps you to size your Screw Chiller. You have to put flow rate, cooling required, and some other data.
However, there are three basic factors to consider before selecting it.
These are the basic factors:
Do not select the Screw Chiller with a larger size when your application can work on a medium size.
Because the extra-large will be of no use and it will cost more power. So, it might not be cost-efficient.
Before selecting it, clean up space for it. Size the Screw Chiller with maximum Features and options to make it easy and efficient.
The Single compressor is one larger compressor. Dual compressors are two smaller compressors. However, it does not affect the size of the Screw Chiller.
Also, consider the availability of the power supply before selecting it. There is an ideal Screw Chiller that comes with various adjustments and works according to needs.
Step 1:
Screw Chiller is very sensitive. It needs to be installed carefully. To avoid any kind of damage, try to move it with a crane.
If the distance is short and within the Installation area, use a fork truck. Foundation is a very important thing for Screw Chiller.
Step: 2
Place an anti-vibration pad between the foundation and Screw Chiller to avoid transmitting vibration and noise.
If you are installing it on the rooftop it is highly recommended to use spring isolators as the sound absorber.
The space for Screw Chiller must be greater than its size. Extra space is needed for air circulating and maintenance.
Step: 3
If Screw Chiller faces directly monsoon rains and the velocity of the monsoon is higher than its fan velocity. It will cause trouble in the process of heat exchanging.
So it is recommended to install it in such a place where does not meet monsoon rains.
The sources of water must be aligned and connected properly. The pipes must be set in a secure place.
Step: 4
A safety valve should also be installed. It keeps the opening pressure below 1.0. Install the manual valve shutoff system in case of maintenance.
All the pipelines from Evaporator should be placed accurately and securely.
The quality standard of water must be good. Install your Screw Chiller in an area that guarantees the quality of water.
As the contaminated water creates algae and other factors which affect its efficiency of working.
The right maintenance increases the life span of your Screw Chiller. However, it comes with spare parts and does not cost expensive maintenance.
Step: 1
It is necessary to check the frequency of vibration of Screw Compressors. The frequent vibration check shows the alignment between the motor and the compressor.
If your Screw Chiller is closed, it is necessary to arrange checkups after every five years.
It has rotors and Screw rotors that need to maintain quarterly to keep its speed high.
Sometimes the contact of Screw rotors with the surface decreases and this results in decreasing efficiency.
Step:2
The capacity control should be frequently checked for leakages. All seals must be inspected and changed with immediate effect if there are any leakages.
Ensure that the capacity control solenoid valves are fine and operational.
The compressors of the Screw Chiller have bearings. Bearings are the rolling elements. Excessive noise and vibration are produced when the bearings are worn out.
Bearings must be replaced during disassembling of Screw Chiller.
Step: 3
Oil is a very crucial part of it and its life-increasing element for it. The bearings are often worn out because of inefficient lubrication.
The proper grade of oil and at recommended level must be used. Change the first oil after 1 year of Screw Chiller's operation and then change it after every three years.
The oil filters must be inspected and changed. If a strainer is present on the filter, change it immediately because the strainer resists motors to work fast.
The maintenance of your Screw Chiller must be performed by professionals and experts in the field to avoid any mishandling.
Screw Chiller Maintenance
Even after the core maintenance and care of the Screw Chiller might get out of order. You need experts to troubleshoot the problems.
Regular Checking Main Connections
If your Screw Chiller shuts down suddenly make sure to check all switches and fuses. Often fuses are blown away and it does not work.
Sometimes the water flow switch disconnects and the water does not pump. Restart the water pump and check the flow again.
Error in Microcomputer
If the microcomputer is not working so check the status of the alarm and inspect the issue. The fault should be set by professionals.
Reliable Source of Water
The total number of gallons of water must be provided to Screw Chiller. Because the insufficient supply of the liquid to the evaporator decreases its efficiency.
If your Screw Chiller does not provide efficient cooling, check the expansion valve, filter, and water pump.
The excess oil makes it deficient. So it is suggested by an expert to keep oil normal and check the oil gauge gradually.
Noise Level Issues
Sometimes the Screw Chiller makes unwanted noise due to the incomplete power supply. The Stable power supply prevents noise production and works at full efficiency.
Resistant in System
The algae-resistant in the Condenser tube decreases the efficiency of the Screw Chiller. It is necessary to check the condenser tube and clean it with cleaning chemicals.
The Screw Chiller also has a motor temperature that's too high, which may fail the motor coil.
Check the resistance of the motor coil and the Problem will be easily detected and solved.
Screw Chiller Troubleshooting
Mostly Screw Chiller uses CFC-free gases. These gases work with a higher frequency. The amount of gases depends on the weight of the Screw Chiller and its Size.
The type of refrigerant gas is always labeled on its printed box.
The Screw Chiller works efficiently with a fluid having sterile deionized water or the propylene glycol solution.
Never use antifreeze or inhibitors these are not safe for your Screw Chiller and may cause corrosion.
The manufacturer Of Screw Chiller also suggests Specified fluid for it.
Shut off the Screw Chiller. Remove the side coverings and disassemble the necessary parts. Take the condenser out clean it with a brush and set it back.
The suitable voltage for the Screw Chiller is 480 volts maximum.
The Screw Chiller comes with sound protection cover or insulation to prevent sound production.
The cooling capacity of the Screw Chiller depends on the size. Its average cooling capacity starts from 2.4 gallons per minute.
The Screw Chiller produces a noise value of 75db.
100% Quality Tested Screw Chiller
This guide has all information you're looking for about screw chillers.
It covers everything, from components, working principles, features, classification criteria, and installation, just to mention a few.
Keep reading this guide to learn more.
Screw chillers are industrial types of cooling systems that use a screw-type of the compressor.
You will compress the refrigerant using the screw compressor as one of the processes leading to fluid chilling.
Screw chiller
Twin-screw compressor
Screw compressors have both female and male parts or rotors that rely on a timing gear to produce compression.
Apart from that, the male and female rotors also work in conjunction with one another to produce compression.
You will have the male rotor which connects directly to the motor which acts as the driving rotor.
On the other hand, the female driver will be the part that receives the driving action (it will be driven).
As the male and female rotors rotate, the volume within their grooves will decrease and compresses the refrigerant.
The refrigerant fluid will flow into the compressor through the inlet forcing the compressor to reduce the tooth space.
It will force the seal line of the scroll compressor to move in the discharge port direction as the compression continues.
Finally, the refrigerant will leave the compressor when the pressure is too high and the seal line is at the discharge point.
You can choose from the list of two types of scroll compressors to use in your screw chilling applications.
Here are the two types of screw compressors that you can choose from.
You can either choose to use the single screw compressor or the twin-screw compressor depending on your application requirements.
Here is a comparison between the two main types of screw compressors.
In the single screw compressor, you will find the main rotor and two gate rotors.
It uses the main rotor as the driving rotor in conjunction with the gate rotor thus producing a compression effect.
Twin-screw compressors have helical grooved twin rotors which help in producing the compression effect.
As the two helical grooved rotors mesh, it will force the refrigerant to compress and flow in the other direction.
Screw compressors are positive displacement machines that have various working chambers and parts.
Here are the main components of the screw chillers that you need to pay close attention to.
It comes complete with two main rotors which include the smaller male rotors and the bigger female rotors.
The female rotor has a connection to the prime mover which basically rotates the male rotor.
The suction valve is responsible for controlling the movement of the gases within the scroll compressors.
You can either use electrical power or pneumatic power to control the movement of gases.
This is the main source of power for the screw chillers that comes in various forms depending on the design.
It has varying power transmission systems that will vary depending on the design or the model of the screw compressor.
This is the part of the screw compressor that lubricates the moving parts and reduces the effects of friction.
It comprises the oil or lubricant tank, oil separators, and oil filters.
Well, among the different types of screw chillers, we have the air-cooled screw chiller and water-cooled screw chillers.
Air-cooled screw chiller
Water-cooled screw chiller
The working principles of the air-cooled and water-cooled screw chillers are similar and produce the same chilling effect.
Apart from that, they have the same components that help in the chilling of different equipment.
The main difference is the fact that air-cooled chillers use air as the main chilling agent and are often noisy.
On the other hand, water-cooled chillers use water as the main chilling agent and are often quiet.
You will also install the air-cooled chiller outside the building and the water-cooled chillers inside a mechanical room.
Successful operations of the screw chillers to produce a chilling effect require a combination of efforts from different components.
Here are the main components of the screw chillers that you ought to pay close attention to.
In this case, the main compressor is the screw compressor which is responsible for compressing the refrigerant and increasing pressure.
There are two types of screw compressors which include the single-screw compressor and twin-screw compressor.
This is the part of the screw chiller which will collect the heat that comes from the system.
It consists of different pipes that contain the liquid that delivers the hot water and heat from the system.
The condenser is responsible for eliminating the heat which the refrigerant collects from the evaporators in the screw chillers.
It has a system that increases the residence time of the refrigerant as it condenses the refrigerant to eliminate heat.
In the expansion valves, various components will assist in controlling the amount of refrigerant.
It will help in reducing the pressure of the refrigerant and supply it in various quantities towards the screw compressors.
You will use the control unit to configure, program, and even monitor every move that occurs within the screw chillers.
It has systems that allow you to connect to the screw chilling system even from a remote location.
You will depend on the lubrication system to lubricate the moving parts of the screw chillers to reduce the effects of friction.
It has different parts such as a lubrication tank, and filters that are capable of providing sufficient and clean oil.
You will have to set the screw chillers according to the right chilling specification that you need.
As soon as you press start on the machine, the refrigerant will move from the refrigerant cylinder to the compressor.
In the screw chillers, we have screw compressors which are responsible for the compression of the refrigerant.
It will compress the refrigerant and increase the pressure as well as the speed of movement.
With that velocity, the refrigerant will flow from the compressor through pipes and delivery systems straight to the evaporator.
While in the evaporator, the refrigerant will collect the heat that comes from the system your intent to cool down,
The evaporator has a series of pipes that will deliver the heat from the system in pipes that contain flowing water.
The refrigerant will collect the heat from the water and leave them cool while the refrigerant heats up changing into gas.
Loaded with enough heat and pressure, the refrigerant will flow from the evaporator all the way to the condenser.
While in the condenser, the refrigerant will encounter cool water or air which will eliminate the heat it holds.
At the same time, it will change form from the gas into a liquid after losing the heat through the condensation process.
The air or water will eliminate the heat and dispose of it properly as the liquid refrigerant moves to the expansion valve.
At the expansion valve, the liquid refrigerant will go through a process of pressure reduction.
It will flow at a slower speed as the expansion valve delivers the liquid refrigerant in bits back to the compressor.
You can locate the screw chillers at any part of the production facility depending on the type of screw chiller.
Water-cooled screw chillers are best located in a mechanical room away from the weather elements that can cause damages.
On the other hand, you will locate the air chillers outside the production facility where it has proper access to enough air.
It is also a very strong machine that can withstand the weather elements and survive for a very long time.
It also produces a lot of noise thus locating it outside in an open space will help in reducing noise irritation.
You can also locate the air-cooled screw chillers in a mechanical room with plenty of ventilation to provide enough air.
Screw chillers have particular quality specifications that assure you of very high-quality, safe, and durable screw chiller machines.
You must ensure that your screw chillers adhere to all the quality specifications such as:
You can use the screw chillers in different types of industrial applications to cool different types of equipment.
Here are some of the industrial applications where the screw chillers come in handy.
You can use screw chillers in the construction industry to cool different types of equipment.
For instance, you can use the screw chillers to change concrete molecular structures or supply chilled water for mixing concrete.
You can also use the screw chillers in the food and beverage industry for several chilling functions.
It will help in cooling food faster before you fill the food in different packages for storage or subsequent distribution.
You can use screw chillers in big factories since they have higher chilling effects than other chillers such as scroll chillers.
It will come in handy in ink printing plants, chemical plants, and automobile factories to chill different types of applications.
Screw chiller regulate the temp of food industry
Screw chillers are one of the best types of chilling systems that you can use in the cooling of different machines.
Here are some of the advantages of using screw chillers in different cooling applications.
Screw chillers are smaller in size and will occupy less installation space in residential and commercial buildings.
They have smaller components that occupy less space thus making them smaller even though the effect is great.
You will also use the screw chillers to cool different equipment efficiently according to the capacity of the industrial application.
You have the freedom of customizing different sizes of screw chillers that can comfortably cool different building installations.
You will experience great energy efficiency by using screw chillers as they use very little energy to produce proper results.
They have proper control on the optimal levels of cooling and never go beyond specific cooling capacities thus conserving energy.
The main type of screw chiller is the water-cooled screw chiller which does not make a lot of noise.
In addition to that, you will house it inside a mechanical room which will help in absorbing the noise.
You will spend less time and money in the process of maintaining the screw chillers because it requires minimal maintenance.
Screw chillers have fewer parts that are very strong and durable that will take ages before they are up for maintenance.
Unfortunately, screw chillers have some limitations despite the numerous benefits that come with them.
Here are some of the limitations that you might experience using the screw chillers.
You will spend a lot on the purchase of the screw chillers as they are quite expensive and have high-quality materials.
The cost of manufacturing the scroll chillers is high because it uses very high-quality materials that are not cheap.
Since the scroll chillers are hermetic systems, you might go through a difficult time trying to repair them.
You will have to purchase original parts for performing repairs which are often quite expensive.
In addition to that, you will find a lot of difficulty in bringing the hermetic screw chillers apart.
You will have to hire professionals or install the clean-in-place system which is often costly to acquire.
Chillers have different types of compressors which help in the compression of different types of refrigerants.
Among the chiller compressors that you can choose from including the scroll compressors and the screw compressors.
A screw chiller is, therefore, a chiller that uses the screw compressor to compress the refrigerant and increase pressure.
On the other hand, scroll chillers use the scroll compressor to compress and increase the pressure of the refrigerants.
Scroll chiller
Different types of screw chillers come complete with common features which you must pay very close attention to.
Here are the main features that you will find in most of the screw chillers.
Screw chillers have various components such as unit compressors that have semi-closed screw compressors.
It also has electronically controlled components with heat exchangers and high-quality copper tube condensers and evaporators.
You must also ensure that it has security features that will help in keeping the machine as well as the operators safe.
Your screw chillers must also exhibit stable performance with very low noise and high levels of durability.
Most of them have very simple operations with an LCD on the control panel for proper programming and monitoring.
It has a very simple, beautiful, and open structure that you can easily install into the production facility.
You can also enjoy the flexibility of operating the screw chillers as you can change compressors accordingly.
Implying that you will have to program the machine and the screw compressors to function according to the product specifications.
When you are maintaining the screw chiller units, you need to focus purely on the main parts.
In the screw chiller compressor unit, we have for main parts including:
Since the screw chillers have very few parts, you don't have to perform a lot of maintenance on the machine.
In that case, all you have to do is disassemble the parts and clean them very well to eliminate the debris.
The oil components have oil tanks and oil filter systems which you need to clean regularly.
Apart from that, you must also fill the tanks regularly and ensure that the reservoirs are up to the right limits,
In addition to that, you must maintain proper lubrication of the moving parts and replace the broken parts regularly.
Finally, you should treat the refrigerant and any fluids on the screw chillers to eliminate the possibility of fouling the system.
Screw compressor maintenance
Screw chillers and centrifugal chillers are types of chillers that you can use in different industrial applications to cool equipment.
Despite the similarity in function, screw chillers and centrifugal chillers differ when it comes to the type of compressor.
Screw chillers have screw compressors while the centrifugal chillers come complete with the centrifugal compressors.
Centrifugal chillers are the most efficient option that you can use when you intend to run the chiller at full load.
Centrifugal chiller
It uses centrifugal force which helps in the compression of the refrigerant to produce enough pressure and speed.
On the other hand, you will use the screw chillers to squeeze the refrigerant between two rotating helical screws.
Since we have different environmental and industrial aspects, you need to choose a screw chiller that will fit your operation requirements.
Here is a step-by-step process that you can follow to assist you in choosing the perfect screw chiller.
You must know the specific heat load you expect to be chilling using the screw chillers.
With this knowledge, you will be able to choose the right type and size of screw chillers to handle the whole process.
In this case, you will choose between the air-cooled screw chiller or the water-cooled screw chiller.
In other words, you will choose the coolant type that will provide you with the perfect flow rates to cool the target temperatures.
You must also have proper knowledge of the environment where you will install the screw chillers.
This information will help in getting the right size of screw chillers that you need and the accessories to fit.
At this point, you will look at the chiller as well as the pump performance curves among different models.
You should settle for the chillers that have the best types of chilling and pump performances to give the best results.
You will complete the process by selecting the best type of screw chiller to suit your application requirements.
Screw chiller coolant
You will purchase the screw chillers at various prices depending on the different types of screw chillers.
The prices vary due to the different sizes of the screw chillers in the market where larger screw chillers cost more.
Apart from that, you will also realize that the better the quality of screw chillers the higher the cost.
In some instances, the minimum order quantity also makes a difference in price as you might have a discount.
You will spend between and 50,000 US dollars to acquire a screw chiller depending on the type of screw chiller.
Well, there are a lot of improvements in terms of developing the screw chillers for better performance.
Here are some of the technological alternatives and trends that you should consider looking at.
In a bid to reduce the cost of energy, there are new technological advancements in the industry such as variable frequency drives.
As the cooling load decreases, the VFD will also reduce the energy output and increase when the cooling load increases.
Om that note, you will be able to save a lot of energy that could be even when the cooling load is low.
You can opt for gas-driven screw chillers especially in areas where the cost of power is very high.
Despite that alternative, you should use gas-driven screw chillers in areas where electric power is a problem.
You can replace the expansion valve using the 2-phase turbines in very large screw chiller applications.
This will help in maintaining the energy potential that is often lost with the use of an expansion valve.
You will also replace the small types of screw chillers with modern large-size screw chillers.
The large size of screw chillers will not only increase the capacity of the chiller but increase the overall efficiency.
Large size screw chiller
You should do a proper calculation to know just how long you will take by using the screw chiller.
In other words, you should know the durability of the screw chillers by calculating the life cycle cost considerations.
Here are the main factors that you should look at when calculating the life cycle cost of screw chillers.
Here, you will look at the final cost of purchasing and installing the screw chillers with costs such as electric bills.
You will look at the amount of money you will spend in paying for energy, treatment, and overall maintenance.
In this case, you will look at the amount of money you will spend in servicing and maintaining the screw chillers.
Well, the main difference between the screw chillers and the reciprocating chillers is the type of compressors.
Reciprocating chillers have reciprocating compressors while the screw chillers have the screw type of compressors.
Despite that difference, most of the factors such as working principles are similar for both types of chillers.
You can also have air- and water-cooled screws or reciprocating chillers for cooling different applications.
Reciprocating chiller
Screw chillers also work efficiently up to a point where it begins developing a few problems.
You can identify the issue affecting the machine through proper troubleshooting procedures.
Here are some of the problems that you might identify with the screw chillers.
High-pressure alarms go off when the pressure within the screw chillers is very high than usual.
Low-pressure alarms will also go off when the pressure within the screw chiller system is low.
You can sort this out through proper control of the pressure systems from the control panel.
You might also experience issues with very high temperatures within the compressor systems.
In such a case, you will activate the thermal protection module to help you in controlling the temperatures well.
At TopChiller, we design and manufacture a range of chiller systems such as air chillers and water chillers.
Contact us today for all your screw chiller needs.
A Screw Chiller is a type of cooling machine that is based on a screw-type compressor.
Its screw-based compressor comes with several innovative and unique features that make it preferable for many specific applications.
A Screw Chiller is a more efficient, less noisy, durable, and lightweight cooling device. It can perform efficiently under harsh environmental conditions.
Screw chiller manufactured by TopChiller
This is the major and most important component of a Screw Chiller. It is responsible for the pressure, flow rate, and speed of the refrigerant.
It performs the evaporation process by which it sucks all the heat content in an excessive amount.
This advanced microprocessor-based control unit is the heart of the Screw Chiller and controls everything in it. It has all the control options and features needed.
Although a Screw Chiller has all the sensors built-in, you can add an extra set of sensors if needed in the tank, compressor, or any other component.
A fluid level alarm system can be added to Screw Chiller, which will notify you when the fluid has reached a certain level. Like, the alarm will ring when fluid is too low or too high.
Its parts should have protective features, less erosion, and wear, be corrosion-resistant, high-grade compressor piston, and have less probability of failure.
All its rotating and moving parts are should be designed to move smoothly and quietly. It creates less noise and less vibration. This makes parts last longer without any kind of damage.
An ideal Screw Chiller can provide 25-30% more chilling efficiency. It is possible due to its screw-based compressor design.
It is the heart of a Screw Chiller that is consisted of a 5 to 6 screw-based compressor. This modern type of compressor is a highly efficient compressor.
Its highly innovative microprocessor-based Control Unit manages and controls all its functions automatically.
Its parts contain protective covers, sensors, lubrication, and other kinds of features for the protection of the components.
Screw chiller control Unit
There are several innovative features of the control unit of a Screw Chiller that makes it an advanced control unit. These features are given below.
The advanced operating feature is the most beneficial feature that is made to make your operation easy and simple.
The advanced PLC-based control unit of the Screw Chiller is the backbone of the advanced operating feature.
In this, your setting and programming of parameters are made easy and simple so that you can set your data precisely with ease.
This feature makes all the operations most accurate. It does not fluctuate to a very minor degree from the programmed parameters. This feature makes the process faster and safer.
The working mechanism resembles the working mechanism of other kinds of chillers. In a Screw Chiller, the cooling cycle begins by cooling of refrigerant.
Then refrigerant is sent to the compressor for pressure, and flow rate regulations.
From the compressor, it enters the refrigeration unit where it collects all the heat and finally in condenser it discards all the heat to maintain optimum chilling by the following process of condensation.
Finally, the whole cycle is repeated from time to time for continuous cooling.
The food industry and the central cooling system of big rooms are the two most unique applications of a Screw Chiller.
It is used for necessary temperature control during food processing, baking, etc. It is also used for post-production functions. These functions include storage, packaging, preservation, etc.
In large industrial plants, where a central cooling system is needed for the whole area or room, a Screw Chiller is utilized there. With its characteristics, it efficiently handles the central cooling of the big areas.
Screw chiller is used for food industry
In construction industries, its importance is related to the concrete processing and curing process.
Concrete is the most vital part without which a construction industry is incomplete and it is manufacturing includes a vital role of Screw Chiller.
When concrete is manufactured it needs constant curing of chilled water. A Screw Chiller provides this constant supply with an accurate set-point of temperature.
It is also used for temperature regulation during setting required hardness and strength of many construction industry products.
The low-temperature level is the range between -45 °C to -110 °C in which it operates.
It is the temperature range between -5 °C to -45 °C.
This is the highest range of temperature and it is between 5 °C to 15 °C.
Lubrication oil temperature is very crucial to keep it working properly. A temperature range lower than the optimum range will cause the lubricant to freeze and becomes dense.
This will increase the friction and heat of friction. The high temperature will cause the lubricant to become less dense and it will not able to tackle friction and perform other functions.
A temperature range from 19 to 22 °C is the optimum temperature range of lubrication oil of a Screw Chiller. It has built-in features that automatically manage this range of temperature.
In case of any fault, extract the lubrication oil and change it will the new one.
Lubrication protocol and the principle is a set of guidelines that must be followed to keep your lubrication oil and lubrication safe and efficient.
Industrial Chiller
Reciprocating industrial chiller
This cylindrical-shaped evaporator is simple to use and operate. The oil return value of the dry shell evaporator is much higher than other evaporators.
In this cold refrigerant is passed through heat exchanger tubes. On passing through tubes it collects heat and evaporates.
In this refrigerant is sprayed on the heat exchanger to form a film. This film refrigerant gets evaporated and desired heat collection is achieved.
A screw compressor is mainly made of rotor, screws, air filters, suction valves, rotation bearings, motor, and discharge valve. Rotors are moving high-speed cylindrical rollers.
These are the most important parts and are responsible for creating the required pressure. Air filters are used to filter the oil and air so that it does not cause any kind of damage to the compressor.
Suction valves are used to create suction and discharge valves are used to release the pressure.
A screw compressor works by sucking the air into it and compressing it to a small volume. As a result of this compression, changes happen in the pressure and temperature of refrigerants.
It works either by reciprocating piston mechanism or rotating screw mechanism. A Screw Chiller generally follows a rotating screw mechanism.
A screw compressor is composed of two screws called make rotor and female rotor. These two screws move at different speeds in opposite directions to each other to create pressure differences.
Water cooled screw chiller designed by TopChiller
Following facts and tips can help you to make a selection between these two.
Following are the major factors and features that you should take into consideration while selecting a Screw Chiller for your industry.
Water cooled screw chiller
The efficient energy control mechanism is one of the most unique and beneficial features of the Screw Chiller.
This mechanism is based on a four-stage capacity control mechanism of 25%, 50%, 75%, and 100%. This mechanism works by two methods.
First, you can program the required set of capacity so that enough energy is provided and it saves your energy from being overused or leaked.
Secondly, it has an automatic load switching mechanism. You can set direction and it will switch to one of the four capacities automatically according to the needs of the process.
Both of the methods are very energy efficient and save a huge amount of your energy expenses.
The multi-level protection feature is a set of advanced features described below.
Ease of installation is one of its major features. You can easily install it on your own by following simple guidelines given by the manufacturers.
All the parts are already assembled and you just need to unpack them and join them according to the guidelines. After joining parts, filling the tank is easy too.
Just fill it to the optimum level prescribed. Connect to a power source and start it. programming parameters on the control unit is very easy and you can do it in a short time.
Sizing of a Screw Chiller can be done on the following considerations.
Based on the above three factors, one can properly size the Screw Chiller for the industry.
Applying layers of lubrication oil on components, joints, etc of the Screw Chiller will reduce the friction produced. It will help to keep it long-lasting and healthy.
Lubrication oil makes movements of the components smooth and easy. On the whole, it makes the process faster and quiet.
It helps in covering small leakages in the surfaces of components.
Screw chiller oil system parts
This is petroleum-based lubrication oil. It is extracted as the byproduct of the petroleum refining process.
It has the same composition as mineral or natural oil. It is made synthetically for the lubrication in Screw Chiller. Is available in many varieties suitable for different compressors.
The two most common types of artificial oil are Polyester Oil and Polyether Oil.
The four load capacities are t 25%, 50%, 75%, and 100%. 25% load capacity is generally used at the start of the process.
It is used to give starting load to the Screw Chiller so that it can be prepared for further process. at 50% and 75%, the solenoid valve system is activated and high-temperature oil is entered into the system.
It is the optimum range of load used. At 100% load capacity, the Screw Chiller is at high risk. If operated at this for a long time, it may face a huge failure.
The major difference is that they both use different kinds of compressors. A Scroll Chiller uses a scroll-type compressor, while a Screw Chiller uses a screw-type compressor.
Secondly, there is a difference in performance efficiency. Generally, the Screw Chiller is 20 to 25% more efficient than the Scroll Chiller.
A Scroll Chiller follows a rotation-based scroll mechanism and a Screw Chiller follows a moving screw-based mechanism that creates suction and pressure.
Scroll chiller
Screw chiller maintenance
A low-pressure alarm is the notification alarm when the suction pressure of the screw compressor is very low.
This low level is below the safe limit and can cause a range of problems. Low suction pressure means a lower amount of air returned and it will cause efficiency to decrease.
When the pressure of discharge in s screw compressor is too high, it is called a high-pressure situation. This situation is notified by an alarm system.
Communication fault generally happens because of some kind of problem in the control unit line or the external device connected.
Due to excessive moister the communication line may get affected by an oxidation reaction and it stops working for a while. To solve this kind of problem, expert help is a must.
You can keep the communication line and circuit board protected by certain measures so that it can be safe from this kind of fault.
A proper monitoring practice is based on following guidelines.
Screw chiller monitoring
The first reason for the overheating of a compressor is friction between the shell and screws.
Originally screw compressor of a Screw Chiller is made highly frictionless but over time due to some problem, it might create friction that causes overheating.
You can solve this problem by simply replacing the compressor or repairing it. Secondly, when the electric resistance of the winding of the screws compressor crosses 141 kilo-ohms, it will cause overheating. Use windings with low electric resistance.
In case of delayed or improper maintenance, it might cause some level of exhaust pressure problem. Maintain it properly and regularly so that this problem never happens.
The inlet valves may get chocked or blocked sometimes and that results in an abnormality in exhaust pressure. Clean them regularly and check the valves properly before starting your Screw Chiller.
This problem might happen due to a faulty motor or any kind of sudden problem in the motor. Repair the motor and always use the high-quality motor in Screw Chiller.
Screw chiller inlet valve
Following are the major problems and their solutions regarding unusual vibrations in a Screw Chiller.
These loosened parts may create unusual vibrations and unbearable sounds when running. Tight the joints and nuts to get rid of this problem.
When the flow rate is too high or contains fluctuation it creates vibration in pipes, condenser, and other units. Set your flow rate to an optimum value.
It can be because of the improper setting of pressure parameters or the pump pressure switch. Correct the setting and start again.
It can happen when the compressor sucks excessive moist air, or too cooled refrigerant into it. Improper setting of expansion valves may also cause this problem.
Inspect the valves and refrigerant temperature to maintain it optimum. Install your Screw Chiller under optimum environmental conditions.
Screw chiller troubleshooting
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