Ten basic performance parameters of refrigeration compressors (technology sharing)

Ten basic performance parameters of refrigeration compressors (technology sharing) 1. Actual gas transmission volume (referred to as gas transmission volume) 　　Under a certain working condition, the gas mass delivered from the suction end to the discharge end per unit time is called the compressor mass air delivery under this working condition, and the unit is. If calculated according to the volume of the inhalation state, the volume of the air delivery is, and the unit is then 　　 2. Volumetric efficiency 　　The volumetric efficiency of the compressor is the ratio of the actual air delivery to the theoretical air delivery 　　 It is used to measure the effective utilization of the cylinder working volume of a positive displacement compressor. 　　 Three, cooling capacity 　　The refrigeration compressor is an important part of the refrigerator and works with other parts in the system, such as heat exchangers, throttling devices, etc., to obtain refrigeration effects. Therefore, its working ability must be expressed intuitively by the cooling capacity produced per unit time-refrigeration capacity, and the unit is one of the important performance indicators of refrigeration compressors. In order to facilitate comparison and selection, it is necessary to specify a uniform working condition to express the cooling capacity of the compressor according to its different use conditions. Table 4-1 lists the different forms of single-stage small reciprocating refrigeration required by the relevant Chinese national standards. The nominal working condition of the compressor and its working temperature. According to the standard, the heat absorbed by the superheat of the suction working fluid should also be included in the cooling capacity of the compressor. 　　 Fourth, heat rejection 　　 heat rejection is the sum of the cooling capacity of the compressor and the equivalent heat input of some compressors. It is discharged through the condenser in the system. This parameter is a very important performance index for the compressor in the heat pump system; it is also necessary to know when designing the condenser of the refrigeration system. 　　 actual refrigeration cycle 　　 The actual refrigeration cycle or heat pump cycle can be seen, the heat rejection of the compressor under certain working conditions. 　　 The energy balance of the compressor is not difficult to find. 　　 in the two formulas 　　-The specific enthalpy of the working fluid at the inlet of the compressor. 　　-the input power of the compressor. 　　-The heat dissipation of the compressor to the environment. 　　 Table 2-2 lists the nominal operating conditions of compressors used in heat pumps specified by the ARI520-85 standard of the American Refrigeration Association. 　　 5. Indicating power and indicating efficiency 　　 The indicated power consumed by the actual cycle per unit time is the indicated power Pi of the compressor, the unit is kw, which is equal to 　　In the formula, Wi——the actual cycle indicated work of each cylinder or working volume, the unit is J. 　　The indicated efficiency hi of the refrigeration compressor refers to the ratio of the theoretical power of the isentropic cycle and the indicated power of the actual cycle required to compress 1kg of working fluid. It is used to evaluate the completeness of the internal thermal process of the compressor cylinder or working volume. 　　6. ​​Shaft power, shaft efficiency and mechanical efficiency The power transmitted from the prime mover to the compressor main shaft is called shaft power Pe, in kW. A part of it, that is, the indicated power Pi, is directly used to complete the compressor's work cycle, and the other part, namely friction power Pm, in kW , Used to overcome the frictional resistance of the moving parts in the compressor and drive auxiliary equipment, such as hydraulic pumps for lubrication. 　　 Seven, electric power and electric efficiency 　　The power input to the motor is the electric power Pel consumed by the compressor, in kW. Electric efficiency* is the ratio of isentropic compression theoretical power to electric power, and it is used to evaluate the perfection of the input power of the motor. 　　 8. Performance coefficient 　　 In order to finally measure the power economy of the refrigeration compressor, the coefficient of performance COP (Cofficient of performance) is adopted, which is the ratio of the refrigeration capacity of the refrigeration compressor to the power consumption under a certain working condition.