What are the causes of compressor overheating Some causes of compressor overheating: high return air temperature, large motor heating capacity, high compression ratio, high condensing pressure, and improper refrigerant selection.
1. High return air temperature In order to prevent liquid return, the return air pipeline generally requires a return air superheat of 20°C. If the return air line is not well-insulated, the superheat will far exceed 20°C. The higher the return air temperature, the higher the cylinder intake temperature and exhaust temperature. Each time the return air temperature increases by 1°C, the exhaust gas temperature will increase by 1 to 1.3°C. Second, the motor heating is large For the return air cooling compressor, the refrigerant vapor is heated by the motor as it flows through the motor cavity, and the cylinder suction temperature is raised again Third, the compression ratio is too high The exhaust temperature is greatly affected by the compression ratio. The larger the compression ratio, the higher the exhaust temperature. Reducing the compression ratio can significantly reduce the exhaust temperature. Specific methods include increasing the suction pressure and reducing the exhaust pressure. 4. Anti-expansion and gas mixing After the suction stroke starts, the high-pressure gas trapped in the cylinder clearance will undergo a reverse expansion process. After de-expansion, the gas pressure returns to the suction pressure, and the energy consumed for compressing this part of the gas is lost during de-expansion. The smaller the clearance, the smaller the power consumption caused by anti-expansion. On the other hand, the larger the suction volume, the greater the compressor energy efficiency ratio. During this process, the gas contacts the high-temperature surfaces of the valve plate, the top of the piston, and the top of the cylinder to absorb heat, so that the gas temperature does not decrease to the suction temperature at the end of the reverse expansion. After the anti-expansion ends, the inspiratory process begins. After the gas enters the cylinder, on the one hand, it mixes with the anti-expansion gas and the temperature rises; on the other hand, the mixed gas absorbs heat from the wall surface and heats up. Therefore, the gas temperature at the beginning of the compression process is higher than the suction temperature. However, because the anti-expansion process and the suction process are very short, the actual temperature rise is very limited, generally less than 5°C. Five, compression temperature rise and refrigerant type Different refrigerants have different thermophysical properties, and the exhaust gas temperature increases differently after undergoing the same compression process. Therefore, for different refrigeration temperatures, different refrigerants should be used. The normal operation of the compressor in the use range should not have overheating phenomena such as high motor temperature and excessive exhaust temperature. Overheating of the compressor is an important fault signal, indicating that there are serious problems in the refrigeration system, or improper use and maintenance of the compressor.
