New hybrid absorption–compression refrigeration system based on cascade use of mid-temperature waste heat

This paper proposes a new hybrid absorption–compression refrigerator powered by mid-temperature waste heat. The system uses an ammonia–water binary mixture as working fluid. It consists of a heat-driven compression refrigeration subsystem and an absorption refrigeration subsystem. These refrigeration subsystems share the same condenser and evaporator. Mid-temperature waste heat is first used in the power and compression refrigeration subsystem to compress ammonia vapor from the evaporator to the condenser. Then the low-temperature waste heat is used in the absorption refrigeration subsystem to preheat the strong solution before entering the rectifier. The exhaust vapor from the ammonia–steam turbine is introduced into the rectifier of the absorption refrigeration subsystem to generate pure ammonia. The new system exhibits superior performance because of the cascade use of waste heat in the two subsystems. With the same waste heat input, the proposed system generates 46.7% more cooling energy than does a conventional ammonia–water absorption refrigerator. The system can serve as an efficient approach to producing cooling with waste heat.