The calculation method of the actual cooling capacity of the refrigeration compressor

The refrigeration compressor is the "heart" of the refrigeration system, absorbing the refrigerant vapor from the evaporator, increasing the pressure and exhausting to the condenser, so that the refrigerant circulates in the system.
　　According to the temperature range, it can be divided into high temperature, medium temperature and low temperature refrigeration compressors. According to the sealing structure form, it is classified as open type; semi-closed; Fully enclosed; Open.
　　Refrigeration capacity is an important indicator to measure the working capacity of the compressor. Basically the actual cooling capacity of all compressors can be calculated using the following three methods.
　　1. Calculated according to the theoretical gas transmission volume
　　The cooling capacity Q of the piston refrigeration compressor under the calculation condition is:

　　In the formula:
　　q0 is the refrigerant per unit mass of refrigerant under the calculated working condition (kJ/kg). qv is the unit volume of refrigerant (kJ/m3) under calculated conditions.
　　Q0 and Qv can be calculated from the thermal force of the cycle. Therefore, as long as the theoretical gas delivery capacity Vh and the gas delivery coefficient λ of the compressor are known, the cooling capacity of the compressor can be calculated. For a refrigeration compressor, when a certain refrigerant is used, its cooling capacity varies according to the working conditions. Because when the working conditions change, the gas delivery coefficient λ of the compressor and the refrigerant unit volume refrigeration capacity qv change accordingly.
　　2. Determine according to the characteristic curve
　　Each type of compressor is usually tested by the manufacturer to draw its performance curve, indicating the relationship between the cooling capacity Q0, shaft power Ne and the evaporation temperature to at different condensing temperatures tk. Therefore, after the compressor model is determined, the cooling capacity under the working condition can be found on the performance chart according to the design working conditions.
　　3. Calculated according to the cold conversion formula
　　Since the same compressor as long as the speed does not change, although the working conditions are different, its theoretical gas delivery capacity is also unchanged. Thus, it is obtained:

　　In the formula:
　　Q λ q are the cooling capacity, gas transmission coefficient and unit volume cooling capacity under the air-conditioning condition (standard working condition) and the design working condition. In this way, if the cooling capacity of the compressor standard or air conditioning condition is known, the cooling capacity under the design condition can be converted according to the above formula.