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This post was last edited by Yixin Electromechanical on 2020-4-27 at 13:38. I. Classification methods 1. Classified by compressor type: piston-type chillers, screw-type chillers, and centrifugal chillers. 2. By fuel type: fuel-type (diesel, heavy oil) and gas-type (kerosene, natural gas). 3. By condenser cooling method: water-cooled chillers and air-cooled water chillers. 4. By energy utilization type: single-cooling type, heat-pump type, heat-recovery type, and dual-function single-cooling/ice storage type. 5. By chilled water outlet temperature: air-conditioning type (7°C, 10°C, 13°C, 15°C) and low-temperature type (-5°C to -30°C). 6. By sealing method: open type, semi-enclosed type, fully enclosed type. 7. Classified by coolant: water-cooled chillers, brine-cooled chillers, and ethylene glycol-cooled chillers. 8. Classified by different energy compensation methods: electrical compensation (compression type) and thermal energy compensation (absorption type). 9. By refrigerant: R22, R123, R134a. 10. By heat source (absorption type): hot water type, steam type, direct combustion type. II. Advantages and disadvantages of various chillers A. Piston-type chillers Advantages: 1. Simple materials are required; ordinary metal materials can be used, they are easy to manufacture, and their cost is low. 2. The system has a simple design, is easy to lubricate, and does not require an exhaust device. 3. The use of multiple heads and high-speed multi-cylinders improves performance. Disadvantages: 1. Many components and parts that are prone to failure; repair is complex and frequent, resulting in high maintenance costs. 2. The compression ratio is low, resulting in a small cooling capacity per unit. 3. The single-head unit has poor adjustment performance under partial load; cylinder unloading is used for adjustment, and stepless adjustment is not possible. 4. It undergoes up-and-down reciprocating motion with significant vibration. 5. High weight index per unit of cooling capacity. B. Screw-type chillers: Advantages: 1. Simple structure, few moving parts and few wear-prone components; the number of such components is only 1/10 that of piston-type chillers, resulting in a low failure rate and a long service life. 2. The circular motion is smooth; there is no surge phenomenon at low load, with low noise and minimal vibration. 3. The compression ratio can reach up to 20, resulting in a high EER value. 4. It is easy to adjust, allowing for stepless regulation within the range of 10% to 100%. It offers high efficiency at partial load, resulting in significant power savings. 5. It has a small size and light weight, allowing it to be used as a vertical, fully enclosed, high-capacity unit. 6. Insensitive to the wet stroke. 7. It operates under positive pressure, so there is no issue of external air intrusion causing corrosion. Disadvantages: 1. The price is higher than that of piston types. 2. The single-unit capacity is smaller than that of centrifugal types, and the rotational speed is lower than that of centrifugal types. 3. The lubricating oil system is complex and consumes a large amount of oil. 4. The noise level of large-capacity units is higher than that of centrifugal types. 5. High precision in machining and assembly is required. C. Centrifugal chiller Advantages: 1. High impeller speed, large air handling capacity, and high capacity per unit. 2. It has few vulnerable parts, operates reliably, features a compact structure, runs smoothly, with low vibration and noise levels. 3. The weight index per unit of cooling capacity is low. 4. The refrigerant contains no lubricating oil, resulting in good heat transfer performance in the evaporator and condenser. 5. High EER value, with theoretical values achievable. 6.996. Easy to adjust, with stepless adjustment within the range of 10% to 100%. Disadvantages: 1. Single-stage compressors experience \"surge\" at low loads, but operate smoothly at full load. 2. Strict requirements are placed on material strength, machining accuracy, and manufacturing quality. 3. When the operating conditions deviate from the design conditions, efficiency drops rapidly, and the reduction in cooling capacity as the evaporation temperature decreases is greater than that in piston-type systems. 4. The centrifugal negative pressure system allows external air to easily penetrate, posing a risk of chemical reactions that could corrode the pipelines. D. Modular chiller units Advantages: 1. It is an improved version of piston-type and screw-type chillers, consisting of multiple chiller units combined together. 2. The unit has a small size, light weight, low height, and occupies little space. 3. It is easy to install, requiring no pre-drilled holes; it can be assembled on-site conveniently, making it particularly suitable for renovation projects. Disadvantages: 1. It is relatively expensive. 2. The number of module chips should generally not exceed 8. E. Water-source heat pump unit Advantages: 1. Energy-saving; it can recover heat during winter operation. 2. No refrigeration room is required; there is no need for large ventilation ducts or circulation water pipes, insulation is not necessary, which reduces costs. 3. Easy to measure. 4. Easy to install and low maintenance costs. 5. Flexible in application and easy to adjust. Disadvantages: 1. Fresh air cannot be utilized to the fullest extent during extreme seasons. 2. The unit generates significant noise. 3. Most of the units are concealed within the ceiling, which poses certain difficulties for maintenance. F. Lithium bromide absorption chiller (steam, hot water, and direct-fired types) Advantages: 1. Few moving parts, low failure rate, smooth operation, low vibration, and low noise. 2. It features simple processing and easy operation, allowing for stepless adjustment from 10% to 100%. 3. Lithium bromide solution is non-toxic and does not damage the ozone layer. 4. Waste heat can be utilized. Waste heat and other low-grade thermal energy. 5. Low operating costs and good safety. 6. Driven by thermal energy, with low electricity consumption. Disadvantages: 1. Its service life is shorter than that of the compression type. 2. It saves electricity but not energy; it consumes a large amount of steam and has low thermal efficiency. 3. The unit operates under vacuum for extended periods, making it easy for external air to penetrate. If air gets in, it causes a reduction in cooling capacity; therefore, strict sealing is required, which poses difficulties in manufacturing and use. 4. The heat rejection load of the unit is higher than that of a compression type, resulting in higher requirements for the quality of cooling water. 5. Lithium bromide solutions are highly corrosive to carbon steel, affecting the lifespan and performance of the unit.