Water Chillers are the most common type of units used for cooling large commercial spaces. Each chiller has its own set of pros and cons. Here, we have listed 5 types of water chillers advantages and disadvantages based on facility budget, available energy sources and the application.
1. The Screw Water Chillers
Screw water chillers are the units that use various types of screw compressors as their mainframes. The utility model is an assembled refrigeration device composed of a screw compressor, a condenser, an evaporator, a thermal expansion valve, an oil separator, an automatic control element and an instrument, etc. At present, Screw water chillers are more and more widely used in the field of refrigeration and air conditioning all over the world. The typical refrigerating capacity ranges from 700KW to 1000KW.
Advantages:
1. Simple structure, few parts, few wearing parts, and long life.
2. It is a stable, low load operation without “surge” phenomenon.
3. The compression ratio and EER value are high.
4. Stepless regulation in the range of 10%~100%, high efficiency under partial load and power saving.
5. Insensitive to wet stroke.
Disadvantages:
1. The price is higher than the piston water chiller. Single capacity than centrifugal water chiller small, low speed than centrifugal water chiller also.
2. The lubricating oil system is complex and consumes a lot of oil.
3. large capacity unit noise than centrifugal water chiller high.
4. High machining and assembly accuracy are required.
2. The Piston Water Chiller
The Piston chillers are chillers whose main engine is a piston compressor. The unit is composed of a compressor, condenser, evaporator, and thermal expansion valve, and equipped with automatic energy regulation and automatic safety protection device. The piston compressor system is relatively simple, this kind of compressor in general low-temperature working conditions with more!
Advantages:
1. Wide applicable pressure range. Strong maintenance.
2. Multi-compressors, high-speed multi-cylinder, performance can be improved.
3. Simple materials, general metal materials available, easy processing with low cost.
Disadvantages:
1. Too many parts, accessories are much more easily damaged.
2. Low compression ratio, small cooling capacity with a single unit, cylinder unloading adjustment. No stepless regulation.
3. The Piston water chillers working up and down reciprocating.
4. Sensitive to liquid shock.
3. The Modular Water Chiller
It is composed of multiple modular chiller units in parallel. Coordinated control by microcomputer circuit work more, can independently adjust energy each compressor, modular units can be made up by as many as 13 units, modular chiller with computer monitoring and control system, control of the whole unit, according to the size of the air conditioning load, regular start-stop the compressor or will high speed to low speed running, including each independent refrigeration system and the machine running.
Advantages:
1. Adjust the number of modules in operation at any time according to the change of cooling load, so as to achieve the best matching between output cooling capacity and air-conditioning load and save energy consumption.
2. Multiple compressors are guaranteed to work in parallel.
3. Lightweight, small size, saving the building area;
4. The modular combination, providing maximum spare capacity for the refrigeration system, and expanding unit capacity is very simple and feasible
Disadvantages:
1. High requirements for water quality. Once scaling and blocking, it will affect the heat transfer of the condenser and evaporator.
2. The cost is high, many parts, vulnerable parts, high maintenance costs.
3. Low compression ratio and small single cooling capacity.
4. Poor adjustment performance under a partial load of a single head, no stepless adjustment
5. Large weight index of unit refrigerating capacity.
4. The Centrifugal Water Chiller
The centrifugal water chiller is cooled by freon refrigerant evaporating in the evaporator to absorb the heat of refrigerant water. The freon wet steam after evaporating is compressed into high-temperature and high-pressure gas by the compressor, which condenses in the water-cooled condenser and turns into liquid, and enters the evaporator for recycling through expansion valve throttle.
Thus making 7 ℃ – 12 ℃ air terminal air conditioning chilled water supply.
Advantages:
1. High rotating speed of impeller, large gas transmission capacity and large single machine capacity
2. Less vulnerable parts, reliable work, compact structure, smooth operation, small vibration, low noise
3. Small weight index of unit refrigerating capacity
4. The refrigerant is not mixed with lubricating oil, evaporator, and condenser of good heat transfer performance
5. EER value is high, which can be adjusted continuously within 10%~100%.
Disadvantages:
1. The single-stage compressor will appear “surge” phenomenon at low load and run smoothly at full load
2. Strict requirements on material strength, machining accuracy, and manufacturing quality
3. When the operating condition deviates from the design condition, the efficiency drops rapidly, and the cooling capacity decreases faster with the decrease of evaporation temperature than the piston type.
4. Centrifugal negative pressure system, external gas easy to invade, there is a risk of chemical changes corrosion pipeline
5. The Water source heat pump unit
A heat pump type integral water-air or water-water air conditioning unit that uses water as the heat source for cooling or heating cycle, and use water as the heat source for heating and water as the exhaust heat source for cooling.
The cold (hot) source is water that circulates in common pipes, water that is extracted from Wells, lakes or rivers, or water that circulates in underground coils to produce cold (hot) wind or cold (hot) water.
The utility model includes a side heat exchanger, a compressor and a heat source side heat exchanger with cooling or a cooling and heating function.
Advantages:
1. Energy saving and heat recovery during winter operation.
2. One unit with multiple operations, stable operation.
3. Significant environmental effects.
4. High energy efficiency ratio.
Disadvantages:
1. Restricted by the available water source conditions and the geographical structure of the water layer.
2. The system is prone to water bunching on the source side and the load side.
3. Affected by energy policies and fuel prices of different regions and countries.
4. The one-time investment and operation fee are relatively high.
