Analysis of centrifugal air compressor waste heat for cooling and heating systems

The waste heat of centrifugal air compressors is mainly generated by the heat energy of compressed air, and is recovered for winter heating and summer cooling by heat exchangers. The recovery amount of waste heat from centrifugal air compressors is mainly influenced by the exhaust temperature of compressed air, the exhaust end difference of heat exchangers, and the temperature of hot water inlet and outlet. The relationship curves between the inlet air temperature, relative humidity, compressed air pressure, and the dew point temperature of compressed air are established. The result shows that the dew point temperature of compressed air increases with the increase of inlet air temperature, relative humidity, and compressed air pressure. Since the exhaust air temperature after heat recovery remains high, the waste heat mainly comes from the sensible heat of compressed air. In practical applications, the heating-to-power ratio is 47.3%, and the cooling-to-power ratio is 23.4%. In terms of waste heat refrigeration, the refrigeration capacity is mainly affected by the driving hot water temperature and coefficient of performance of the hot water absorption chiller. The use of two-stage hot water absorption chillers has better compatibility with the system and is more commonly used. The total investment payback period of the system is 0.38 years, with most of the benefits coming from heating. The investment payback period for the refrigeration equipment is 1.82 years.