The Difference Between Ammonia Chiller and Refrigerant Chiller
1. One-time investment. In general, large and medium-sized ammonia refrigeration systems have slightly more investment than fluorine refrigeration systems of the same scale. The refrigeration unit of the fluorine refrigeration system has a high degree of automation and relatively little investment. The ammonia plant has a huge system, many auxiliary machines, many high-pressure vessels, complicated pipelines, many valves, and each component is relatively large in size and bulky. The fluorine machine system adopts intensive design, the unit is delivered as a whole, the unit occupies a small area, the structure is simple, and it is easy to use.
2. Operating costs. The refrigerant of the ammonia refrigeration system is cheap, and the unit refrigeration capacity of the refrigerant is large, the power consumption is less, and the operating cost is low. Fluorine refrigeration systems have relatively high working fluid prices, small unit refrigeration capacity, relatively high power consumption, and high operating costs.
3. environmental protection characteristics. The refrigerant ammonia in the ammonia refrigeration system is a natural working fluid with ozone depletion coefficient and no pollution to the environment. The CFCs working fluid of the fluorine refrigeration system has a low ozone depletion coefficient ODP and a small global warming coefficient GWP due to its ozone-depleting characteristics, which has a certain destructive effect on the environment.
4. energy-saving features. The refrigeration coefficient COP of the ammonia refrigeration system is larger, and the energy saving effect is better. The refrigeration coefficient of fluorine refrigeration system is small, and the energy saving effect is poor.
Both refrigeration systems can adopt the following energy-saving measures to reduce energy consumption and increase the refrigeration coefficient:
1. Lower the condensing temperature.
2. Prevent the evaporation temperature from being too low and keep the appropriate evaporation temperature.
3. The liquid is then cooled before the throttle valve.
4. The main engine, water pump and fan can use frequency conversion technology to reduce energy consumption.
5. Adopt multi-stage compression cycle.
6. Some refrigeration working fluids (such as F-134a) can use a regenerative cycle.
7. Use variable flow control.
8. The electronic expansion valve is used for liquid supply.
9. Apply PLC, PID technology, electronic computer technology and modern communication technology to realize automatic control.
10. The use of high-efficiency digital scroll type, screw type refrigeration compressor with economizer, and improvement of piston type compressor.
11. Use high-efficiency evaporative condenser and plate evaporator.
12. During the operation of the refrigeration system, always release air, prevent oil, defrost, clean the scale of the condenser and evaporator.
13. The air conditioning system can use solar heat pumps, air source heat pumps, water source heat pumps and ground source heat pumps, and maintain an economical and reasonable indoor temperature.
14, using multiple online groups.
15. Under low temperature conditions (below-40), NH 3 /CO 2 cascade refrigeration cycle system is adopted.
16. Centrifugal refrigeration units can be used for large-scale central air-conditioning systems, and small and medium-sized air-conditioning systems can be used. VRV direct evaporative air conditioning system; where waste heat is available, absorption air conditioning units can be used.
17. The refrigeration system adopts hot gas defrosting, which is more energy-efficient than electric defrosting.
18. The refrigeration system adopts heat recovery heat exchanger, etc.
5. Safety. When the volume concentration of ammonia in the air reaches 0.5-0.6%, people can be poisoned by staying in it for half an hour, and it can be ignited when the concentration reaches 11-14%. When the concentration reaches 16-25%, it will cause an explosion. my country has clearly stipulated In densely populated places, toxic refrigerants that are inflammable and explosive cannot be used. Freon is colorless, odorless, non-combustible, non-explosive, and has stable chemical properties (my country's national standard GB7778-87 comprehensively considers the flammability, explosiveness, and direct harm to the human body of the refrigerant, and classifies the refrigerant safely. , R22 is listed as the first safety category, and R717 is listed as the second safety category), fluorine can be applied to high temperature, medium temperature, and low temperature refrigerators to meet the requirements of different refrigeration temperatures, and the lowest evaporation temperature that can be produced It is -80°C.
6. Liquid supply and return gas pipeline. Ammonia systems generally use bottom-in and top-out methods to connect evaporators, and fluorine systems generally use top-in and bottom-out methods to connect evaporators to facilitate oil return. The horizontal suction pipe of the ammonia system should slope to the circulation barrel or gas-liquid separator, and the horizontal suction pipe of the fluorine system should slope to the compressor.
7, liquid supply method. Both the ammonia system and the fluorine system can use direct liquid supply, liquid pump liquid supply and gravity liquid supply to supply liquid to the evaporator.
8. Scope of application. Both the ammonia system and the fluorine system are medium-temperature refrigeration working fluids with moderate pressure and temperature. They can be used for refrigeration, air conditioning, industrial refrigeration, beer and pharmaceutical industries. The fluorine system is safer when used in direct evaporative air conditioning systems. The ammonia system can use indirect cooling (via refrigerant) for air conditioning.
9, the degree of automation control. The fluorine system is highly automated and generally does not require manual operation, which can save labor costs. Ammonia systems are mostly manually operated, with low automation, but good operational stability (now ammonia refrigeration equipment is also highly automated).
10. Comparison of noise and vibration. The ammonia machine is relatively large in size, with great noise and vibration, which has a great impact on the environment. The fluorine machine system has low noise and vibration.
11. The solubility of ammonia and oil is small. An oil film is easy to form on the surface of the heat exchanger of the ammonia system, which affects heat transfer. Therefore, the evaporator, condenser, accumulator, intercooler, and oil-ammonia separator should be drained regularly. In the fluorine system, fluorine and oil dissolve each other, and no oil film will be formed on the surface of the heat exchanger, which will not affect heat transfer, but too much oil in the evaporator will increase the evaporation temperature. The fluorine system is generally equipped with an automatic oil return device. The design and installation of the fluorine system pipeline should consider the setting of an oil return bend, and the parallel unit should consider the oil balance problem.
12. Applicable. Ammonia systems are generally suitable for large and medium-sized refrigeration, industrial refrigeration, ice making, artificial ice rinks and indirect central air-conditioning. Fluorine systems are generally applicable to refrigerators, freezers, display cabinets, household air conditioners, commercial air conditioners, small and medium-sized cold storage and freezing, factory low temperature air conditioners, mine air conditioners, ice cream, cold drinks, edible ice, artificial ice rinks and small industrial refrigeration.
13. Equipment, piping and valves of the refrigeration system. Ammonia system pipelines all use seamless steel pipes, steel vessels and equipment, aluminum alloy pistons, seamless steel pipe evaporators or aluminum alloy pipe evaporators; valves and pipe fittings use ammonia-specific products. Compressors are mostly piston type and screw type. The fluorine system pipeline adopts copper pipes and seamless steel pipes, steel equipment, copper pipe evaporator or aluminum alloy pipe evaporator, valves and pipe fittings adopt fluorine special products. Compressors include digital scroll type, screw type, piston type and so on.
14. When moisture exists in the ammonia system, the ammonia will corrode equipment and pipelines. When the fluorine system contains moisture, the fluorine will also corrode equipment and pipelines, and easily form ice plugs. Therefore, the fluorine system should be equipped with a filter drier.
15. Find leaks. Ammonia has a pungent fishy odor. The ammonia system can use the characteristics of phenolphthalein test paper to turn red when encountering ammonia and litmus test paper to turn blue when encountering ammonia to find leaks. Fluorine is colorless and odorless. The fluorine system leak detection can use soapy water application method and electronic leak detector method.
16. Decision-making on the selection of ammonia refrigeration system and fluorine refrigeration system. It should be determined by comprehensive analysis based on specific application environment and temperature conditions, investment and operating costs, environmental protection requirements, energy saving requirements, safety requirements, operational stability, and automation control requirements.
