The selection of the refrigeration device for the dust-free workshop cooling is the central link in the process of determining the refrigeration scheme, and the main types of refrigeration devices are as follows.
1, compression refrigeration device
Compression refrigeration devices include piston (reciprocating), centrifugal and screw type three.
The main equipment of piston (reciprocating) compression refrigeration device is piston refrigeration compressor, commonly used working medium ammonia (NH3), freon-12, 22(F-12, 22). This kind of equipment is driven by electric motor, easy to use, many varieties, complete products, can meet the requirements of various types of air conditioning cooling, and is widely used. However, a large investment, high equipment costs, large power consumption, maintenance and management is more complex.
The main equipment of centrifugal compression refrigeration unit is centrifugal refrigeration compressor, and the commonly used working medium is freon-11, 113, 114(F-11, 113, 114). The machine has the same principle as the piston type refrigeration compressor, but it only has rotary movement, stable operation than the piston type, small vibration, fewer parts, often combined with the evaporator and condenser, compact equipment and small footprint. The refrigeration capacity of centrifugal refrigeration compressor is large, so only when the cooling consumption of air conditioning is large, this type of equipment is selected.
The main equipment of screw compression refrigeration device is screw refrigeration compressor, and the commonly used working medium is freon-12, 22, ammonia (F-12, 22, R717). At present, the production of screw refrigeration compressor compared with the piston, although the efficiency is slightly lower, but because of its simple structure, small volume, high suction coefficient, low exhaust temperature, single stage compression ratio, insensitive to wet stroke, small exhaust pulsation, fewer wearing parts, long column repair cycle, cooling capacity can be stepless adjustment and other advantages, so it has been widely used in various refrigeration devices. The machine is generally used in refrigeration devices with a capacity range of (120-800)x105kJ \ h and has better technical and economic indicators.
2, absorption refrigeration device
Absorption refrigeration units use thermal energy to refrigerate. Common ammonia - water absorption refrigeration unit and water - lithium bromide solution absorption refrigeration unit. The former is suitable for low temperature freezing; The latter is suitable for air conditioning cooling, making air conditioning or process cold water above 4 ° C. The water in the lithium bromide absorption refrigeration is the working medium, and the lithium bromide aqueous solution is the absorbent. Its advantages are as follows.
It has great adaptability to the pressure of the steam heat source. When the steam pressure is 0.02-0.1mpa, a single lithium bromide absorption refrigerator can be used, and when the steam pressure is 6.0-1.0mpa, a dual-effect lithium bromide refrigerator can be used.
Secondly, the equipment is simple, basically a combination of heat exchangers, easy to manufacture, in addition to low-power shield pump, vacuum pump, no moving parts, so small vibration, smooth operation; The equipment works under vacuum, the working medium is odorless, non-toxic, harmless to people, safe to use, simple operation and management; It is easy to realize the automation of equipment operation, and the cooling capacity can be automatically adjusted in the range of 10% to 100%; Strong adaptability to the water temperature of the cooling water, even if it reaches 37 ~ 38℃, the equipment can still operate normally; Save energy, under the same conditions of single cooling capacity, the power consumption of lithium bromide refrigerator is only about 5% of the compression refrigerator, which is very suitable for areas where the power supply is tight and the heat source is sufficient. However, lithium bromide absorption refrigeration also has shortcomings and limitations of use, mainly in the case of lithium bromide aqueous solution in contact with air, the metal has a strong corrosion, once it is corroded, not only affect the heat transfer effect, reduce the service life, but also cause equipment damage, so the equipment must be strictly sealed, in the operation management also need to pay attention to.
3, steam jet refrigeration device
Steam jet refrigeration unit is also a kind of equipment that uses heat energy to refrigerate, using water as refrigerant and steam as cooling power. Steam pressure requirements 0.2-0.8mpa, its main advantages are: equipment under vacuum, in addition to the pump, no rotating parts; The refrigerant is water, harmless to people, safe to use, easy to operate; The equipment is simple and easy to manufacture, and the general machinery factory or machine repair shop can be processed and manufactured; The equipment has a small investment and can be installed outdoors, saving civil construction costs; The waste heat in industrial enterprises or the heating boiler in industrial enterprises can be used for heating and heating in winter and steam and cooling in summer.
The main disadvantage of steam jet refrigeration is low efficiency, and it is uneconomical to set up special boilers and use small heating boilers for steam supply. It can be used when the freezing water temperature is above 5 ° C, and it is more economical when it is above 100 ° C. Its efficiency varies with the temperature of chilled water, and the lower the temperature of chilled water, the greater the amount of steam consumed and the lower the efficiency. In addition, the cooling water quantity is large, and at the same cooling capacity, the cooling water required by the steam jet refrigerating machine is about 1.5 times that of the compression or brominated absorption system, which is inappropriate for an area with tight water supply.
Industrial air conditioning, chemical fiber industrial air conditioning, chemical fiber industry refrigeration ,textile industrial air conditioning , dust-free workshop cooling, ventilation pipeline, cooling tower, freezer and other air conditioning units and accessories.
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