Screw chillers having air cooled screw chiller and water cooled screw chiller. Compared with scroll compressor chillers, screw chillers with large cooling capacity for some certain industrial or commercial usage.
With competitive price and timely delivery, Huateng sincerely hope to be your supplier and partner.
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&#;
1. What is a Screw Chiller?
A screw chiller is an industrial chiller with screw type of 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 less number of 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 environment.
Screw Chiller
2. What is the difference between Screw Chillers and Piston Chillers?
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 rises. Most air compressors either are reciprocating piston type or rotary screw type.
2.1 Reciprocating (Piston Type) Chiller
A reciprocating compressor has a piston move downwards, reducing 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 causes 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. Separated compressor compartment is needed for its noise and vibration.
Small compressors are air cooled but large machines from 30HP and above are only water cooled.
2.2 Rotary Screw chiller
Rotary compressors, on the other hand, use rollers.
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.
2.3 Advantages and Disadvantages of Screw Chillers compared to Piston Chillers
Advantages:
1)Less possibility to break down: As screw compressor has only two moving parts which 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, 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 air flow 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.
3. Screw chiller working principle and flow diagram
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 working and its flow diagram as below:
For air cooled screw chiller:
The air-cooled screw chiller having 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 a 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. This is the four processes of the refrigeration cycle.
This is also the main working principle of the air-cooled screw chiller.
Air Cooled Screw Chiller Working Principle
Features of air cooled screw chiller:
1. Semi-hermeitc 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 more Screw Type Chiller Unitinformation, please contact us. We will provide professional answers.
150Ton Air Cooled Screw Chiller
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.
Water cooled screw chiller must go along with a cooling tower, water pump, insulation water tank, to make a complete water cooling system.
Water Cooled Screw Chiller Working Principle
Features of water cooled screw chiller:
Efficient semi-hermetic screw compressor, the screw chiller unit 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 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 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.
120Ton Water Cooled Screw Chiller
1. 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 of intrusion of outside air.
150Ton Screw Chiller in Kuwait
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Industrial chillers play a vital role in maintaining process temperatures across several industries. Brewery glycol chillers, MRI chillers, and hydroponic water chillers are just a few examples of this equipment being used in different trades.
While the benefits of using a process chiller for heat-sensitive applications are well-established, operators must ensure these cooling systems are used according to the manufacturer&#;s instructions. Owners and users must familiarize themselves with all the safety features of their chiller units to ensure smooth operating with minimal potential hazards.
Like every other type of industrial equipment, chillers require operators to take necessary safety precautions. Ignorance of the potential hazards that chillers can pose may lead to industrial accidents such as refrigerant leakages or explosions that could cause bodily harm to workers.
To prevent these accidents, all chiller units must be operated within certain safety parameters.
Industrial chillers use refrigerants that circulate in closed channels to achieve cooling. Maintaining the integrity of these refrigerant systems requires strict adherence to laid down safety and maintenance protocols.
Some types of chiller refrigerant can pose a serious environmental hazard to surrounding workers if they don&#;t have adequate knowledge of chiller safety features that cut off refrigerant circulation in case of a leak.
Typical chiller units come preinstalled with various switches and features that help prevent the onset of industrial hazards during their operation. Operators must familiarize themselves with all these features to ensure an efficient and safe process.
Outlined below are some key safety features that standard industrial chiller units possess.
A vital safety feature in industrial chillers is the flow safety thermostat. These devices detect adverse changes in temperature within the refrigerant circuit. When unfavorable thermal conditions arise within the chiller&#;s refrigeration unit, the flow safety sensor will detect it and cut off the coolant circulation. Although different circumstances can trigger the safety flow thermostat, the most common cause is a clogged strainer.
A tripped flow safety thermal sensor will require manual resetting by a technician; however, operators must accurately determine the triggering cause to prevent further damage to the process cooling system.
Industrial chillers also come equipped with low-temperature sensors. Freeze safety devices detect low thermal levels and switch off to prevent the refrigerant from freezing over. An automatic reset occurs when the temperature of the chiller fluid returns to normal levels.
Another safety feature of a typical chiller system is the liquid flow switch. This mechanism detects a reduction in the volume of fluid entering the evaporator and automatically cuts off flow. The switch resets when fluid levels are restored to normal.
Compressor units are a key part of refrigeration systems including those in chiller units. These compressor devices handle refrigerants circulating under a tightly regulated pressure range. Sudden increases or decreases in the pressure levels within a compressor unit can cause significant damage to the cooling unit and expose operators to toxic chemical leakages.
To ensure compressor pressure is kept within safe limits, most units are manufactured with three safety features:
Low pressure cut out devices help protect the chiller unit compressors against an adversely low pressure while preventing the entry of air into the system in cases where a vacuum develops. Further, low-pressure safety units shut down refrigerated compartments when there is an obstruction to gas return with a corresponding reduction in system pressure. Low-pressure safety switches automatically restore chiller function once compressor pressures have normalized.
Elevated pressure levels within a chiller compressor unit can be attributed to various causes including cooling water loss, high environmental temperatures, and gas discharge line obstruction. To protect the compressor from the damaging effects of high pressures, a cut off automatically detects and shuts it down.
By design, high-pressure cut-offs must be manually reset. This ensures operators investigate the possible causes of the compressor shut down before restarting the system.
The oil used to prevent friction within the bearings of a compressor is usually under pressure by an attached oil pump. A faulty pumping mechanism will reduce the amount of oil reaching the bearings thus exposing them to rapid wear. The use of a compressor low oil safety cut out will switch off the compressor once it detects a fall in the pressure of the lubricant oil supplied to it.
For more than thirty years, Cold Shot has been among the leading industrial chiller manufacturers in the US. As we continue to manufacture the best industrial cooling solutions, the provision of a world-class satisfactory customer experience remains our top priority.
Request a quote on one of our units today, or find more information about the wide range of air-cooled chillers and water-cooled chillers that we offer on our website.
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