Design and analysis of waste heat recovery from residential air conditioning units for cooling and pure water production

The present article reports on the analysis of waste heat and condensate recovery from residential air conditioning (AC) units in different climatic regions in Saudi Arabia. Simulation results obtained using a transient dynamic model show that significant amounts of waste heat and water condensate are rejected to the environment in hot and humid climate regions. A multi-generation system for simultaneous cooling and pure water production using condensate and waste heat recovery is designed and implemented in TRNSYS environment. A refrigerant to water de-superheater is introduced after the compressor to extract energy from the high temperature superheated refrigerant gas for heating saline water that is used as a feed to drive an air gap membrane desalination unit. The production of pure water is analyzed for both batch and continuous cooling modes of the membrane desalination unit. The amount of pure water production shows the potential of proposed system to supply pure water requirements in hot and humid climates in Saudi Arabia. The monthly average coefficient of performance of multi-generation residential AC units with continuous cooling of desalination unit is shown to be improved by similar to 6.61%. The monthly average gained output ratio of membrane desalination unit is higher than 1.14.