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Piston type water chiller
Advantages:
1. Simple materials, general metal materials, easy processing, low cost;
2. Simple system device, easy lubrication, no need of exhaust device;
3. The performance can be improved with multi-head and high-speed multi-cylinder.
Disadvantages:
1. More parts, more vulnerable parts, complex maintenance, frequent maintenance and high maintenance costs;
2. Low compression ratio, low cooling capacity of single machine;
3. Poor adjustment performance under partial load of single machine head, adjustment of unloading cylinder, not ungraded adjustment;
4. It is a reciprocating movement with high vibration;
5. The weight index of unit refrigerating volume is large.
Screw chiller
Advantages:
1. Simple structure, less moving parts, less vulnerable parts, 1/10 of the piston type, low failure rate and long life;
2. Smooth circular movement, no "surge" phenomenon during 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. Easy to adjust, it can be stepless within the range of 10% to 100%, with high efficiency and significant power saving when part of the load;
5. Small size and light weight, it can be made into a vertical full-enclosed large-capacity unit;
6. Not sensitive to wet stroke;
7. Under normal pressure, there is no external gas intrusion corrosion problem.
Disadvantages:
1. The price is higher than that of piston type;
2. The capacity of single machine is smaller than that of centrifugal type, and the speed is lower than that of centrifugal type;
3. The lubricating oil system is complex and consumes a large amount of oil;
4. Noise of high-capacity units is higher than centrifugal ones;
5. High machining precision and assembly precision are required.
Centrifugal chiller
Advantages:
1. High rotating speed of the impeller, large amount of gas transmission and large capacity of single machine;
2. Less vulnerable parts, reliable work, compact structure, stable operation, small vibration and low noise;
3. The weight index of unit refrigerating volume is small;
4. The refrigerant is not mixed with lubricating oil, and the heat transfer performance of evaporator and condenser is good;
5. EER value is high, theoretical value can reach 6.99;
6. Convenient adjustment, no step adjustment within 10%~100%.
Disadvantages:
1. The "surge" phenomenon occurs when the single-stage compressor is under low load and runs smoothly at full load;
2. Strict requirements on material strength, machining precision 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, the external gas is easy to enter, and there is a risk of chemical change and corrosion of the pipeline.
Modular cold water unit
Advantages:
1. It is an improved piston type and screw type, which is composed of several cold water units.
2. The unit is small in size, light in weight, low in height and small in land area;
3. Simple installation, no holes need to be reserved for installation, convenient on-site assembly, especially suitable for renovation projects.
Disadvantages:
The price is more expensive.
2. The number of modules should not exceed 8.
Water source heat pump unit
Advantages:
1. Save energy and recycle heat when running in winter;
Take it from nature;
3. Relatively high energy efficiency ratio;
4. Convenient installation and low maintenance cost;
5. Flexible application and convenient adjustment.
Disadvantages:
1. Fail to make the best use of the new wind in the excessive season;
2. The unit is noisy.
6. Lithium bromide absorption chiller
(steam, hot water and direct combustion type)
Advantages:
1. Less moving parts, low failure rate, stable movement, low vibration and low noise;
2. Simple processing and convenient operation, capable of 10%~100% stepless adjustment;
3. Lithium bromide solution is non-toxic and has no damage to the ozone layer;
4. Waste heat can be used. Waste heat and other low-grade thermal energy;
5. Low operating costs and good security;
6. Take heat energy as the power and use less electricity.
Disadvantages:
1. Shorter service life than compression type;
2. Energy saving is not energy saving, high steam consumption and low thermal efficiency;
3. The unit operates under vacuum for a long time, and the external gas is easy to enter. If the air invades, the cooling amount will decrease, so the requirements are strict. Sealing, which brings inconvenience to manufacture and use;
4. The heat discharge load of the unit is larger than that of the compression type, which requires higher water quality of cooling water;
5. Lithium bromide solution has a strong corrosive effect on carbon steel and affects the service life and performance of the unit.