In refrigeration systems, abnormal increases in compressor exhaust temperature will not only seriously affect the service life of the compressor, but also cause the performance of the entire system to decline. So, what factors exactly cause this problem?
1. Insufficient heat dissipation of the condenser
When the condenser is too small or the heat dissipation efficiency is low, the heat cannot be dissipated in time, causing the condensation temperature and pressure to rise, which in turn leads to an increase in the compressor exhaust pressure and temperature. When this phenomenon continues to a certain extent, the compressor will activate the overheating protection mechanism. In addition, the circulating fan of the heat pump in the dryer has a direct impact on the heat dissipation effect and drying efficiency of the condenser, and whether the air volume is sufficient is crucial.
2. Excessive refrigerant filling
When the condenser is filled with excessive refrigerant, its effective heat dissipation area will be reduced accordingly, which will lead to an increase in condensation pressure and condensation temperature. This will not only increase the exhaust pressure and exhaust temperature, but also increase the starting load of the compressor, which may make it difficult to start the motor, and even in severe cases, the motor will burn out due to excessive current.
3. Pressure ratio is too high
As the pressure ratio increases, the specific work and exhaust temperature will also increase accordingly. Exhaust temperature is closely related to the compression ratio. The larger the compression ratio, the higher the exhaust temperature. In order to significantly reduce the exhaust temperature, you can try to reduce the compression ratio. Specific measures include increasing the suction pressure and reducing the exhaust pressure.
The suction pressure is affected by the evaporation pressure and the resistance of the suction line. By increasing the evaporation temperature, the suction pressure can be effectively increased, thereby quickly reducing the compression ratio and reducing the exhaust temperature. At the same time, reducing the resistance of the return line can also increase the return pressure, such as timely replacing the clogged return filter, shortening the length of the evaporator pipe and the return line. In addition, insufficient refrigerant will also cause low suction pressure, so it is necessary to ensure that the refrigerant is not lost and replenished in time.
Practice has proved that the method of reducing the exhaust temperature by increasing the suction pressure is simpler and more effective than other methods.
4. The return temperature is too high
The return temperature, that is, the temperature of the refrigerant in the return line, is relative to the evaporation temperature. In order to prevent liquid backflow, the return air pipeline is usually required to maintain a return air superheat of 20°C. However, if the return air pipeline is not well insulated, the superheat may significantly exceed 20°C. The increase in return air temperature will cause the cylinder suction temperature and exhaust temperature to rise accordingly. Specifically, for every 1°C increase in return air temperature, the exhaust temperature may rise by 1 to 1.3°C.
The increase in exhaust temperature is affected by many factors, which may be different in actual applications such as dryer heat pump systems, air conditioning systems, and refrigerator refrigeration systems. However, from a system level analysis, the reasons for excessive exhaust temperature usually include the above aspects. Specific problem analysis needs to be carried out in combination with actual conditions.