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Two stage compression and cascade refrigeration system of constant temperature and humidity machine is introduced
July 26, 2013 source: navigation instruments Author:

introduce Constant temperature and humidity machine Stage compression and cascade refrigeration system

Constant temperature and humidity machine Two stage compression refrigeration system

Constant temperature and humidity machine Why do we use two now Stage compression What about:

In order to achieve a lower evaporation temperature, lower evaporation pressure is required, and the condensation pressure is related to the ambient temperature, so the pressure ratio must be increased. For the single-stage vapor compression refrigeration system, when the compressor increases, the gas transmission capacity of the compressor decreases, the refrigerant throttling loss increases, the unit refrigerating capacity decreases, and the refrigeration efficiency greatly decreases. When the compression ratio increases to a certain value, the compressor can not even inhale, thus losing the refrigeration capacity. In addition, it will cause the exhaust temperature of the compressor to rise, which will worsen the lubrication condition.

Generally, the maximum compression ratio of single-stage ammonia compressor shall not exceed eight And Freon compressor is no more than ten When lower evaporation temperature is needed, two-stage compression refrigeration system and cascade refrigeration system are needed.

Constant temperature and humidity machine The form of two stage compression refrigeration cycle

The two-stage compression refrigeration cycle is to use a low-pressure compressor for the refrigerant vapor from the evaporator ( Or low pressure stage of compressor ) Compress to intermediate pressure, and then use high pressure compressor ( Or high pressure stage of compressor ) Compress to condensation pressure. Most of the two-stage compression chamber adopts intermediate cooling, and the degree of cooling includes complete cooling and incomplete cooling. The so-called complete cooling refers to cooling the exhaust gas of the low-pressure compressor to the state of dry saturated steam, while the incomplete cooling means that the exhaust gas of the low-pressure compressor is not cooled to the state of dry saturated steam, which only reduces the superheat of the exhaust gas of the low-pressure compressor to a certain extent. There are two kinds of throttling process: one-stage throttling and two-stage throttling two . three The high-pressure compressor is started first, and then the low-pressure compressor is started after a period of delay.

Intercoolers are widely used in refrigeration systems using screw and centrifugal compressors. The refrigeration cycle with economizer is the same as the two-stage compression refrigeration cycle, which can save energy, improve the performance coefficient of the unit, and reduce the exhaust temperature of the compressor, especially in the low temperature condition.

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