Reasons for Power Consumption of Screw Chillers

2021-09-10

Reasons for power consumption of screw chillers
1. As the evaporation temperature decreases, the compression ratio of the compressor increases, and the energy consumption per unit of cold production increases. When the evaporation temperature drops by 1℃, it will consume 3%-4% more electricity. Therefore, reduce the evaporation temperature difference as much as possible and increase the evaporation temperature, which not only saves power consumption, but also increases the relative humidity of the cold room.
2. As the condensing temperature increases, the compression ratio of the compressor increases, and the energy consumption per unit of cold production increases. The condensing temperature is between 25°C and 40°C, and every 1°C increase will increase the power consumption by about 3.2%.
3. When the heat exchange surface of the condenser and the evaporator is covered with an oil layer, it will cause the condensation temperature to rise and the evaporation temperature to decrease, resulting in a decrease in cold production and an increase in power consumption. When a 0.1mm thick oil layer accumulates on the inner surface of the condenser, it will reduce the compressor’s cooling output by 16.6 and increase power consumption by 12.4; when the 0.1mm thick oil layer accumulates on the inner surface of the evaporator, in order to maintain the set low temperature requirements, The evaporation temperature drops by 2.5°C and the power consumption increases by 9.7.
 4. When air accumulates in the condenser, it will cause the condensing pressure to rise. When the partial pressure of non-condensable gas reaches 1.96105Pa, the power consumption of the compressor will increase by 18.
5. When the scale on the tube wall of the condenser reaches 1.5mm, the condensing temperature will increase by 2.8℃ compared with the temperature before the scale, and the power consumption will increase by 9.7.
 6. The surface of the evaporator is covered with a layer of frost to reduce the heat transfer coefficient, especially when the outer surface of the fin tube is frosted, which not only increases the heat transfer resistance, but also makes the air flow between the fins difficult and reduces the appearance The heat transfer coefficient and heat dissipation area. When the indoor temperature is lower than 0°C and the temperature difference between the two sides of the evaporator tube group is 10°C, the heat transfer coefficient of the evaporator is about 70 before frosting after one month of operation.
7. The gas sucked in by the compressor allows a certain degree of superheat, but if the degree of superheat is too high, the specific volume of the sucked gas will increase, its cold production will decrease, and the relative power consumption will increase.
8. When the compressor is frosted, quickly close the suction valve, which drastically reduces the cold output and relatively increases the power consumption.

screw chillers