Performance Comparison of Heat-Driven and Electric-Driven Ammonia Heat Pump Systems

The objective of this study is to evaluate the solid sorption technology for residential cooling applications. The solid sorption technology uses natural gas as the primary energy source for compressing and circulating the refrigerant in the air-conditioning system. The system delivered 6.7 kW of cooling at 35°C outdoor temperature. The cooling gas COP was 0.32 at 27.8°C outdoor temperature. An ammonia vapor compression system was established and tested by operating a steady state mechanical compressor in place of the cyclic thermal compressor to evaluate and verify the cyclic performance of the sorption system. The system’s thermal compressor efficiency was almost one-third that of the mechanical compressor based on the input power of the primary energy source for each compressor. The testing revealed that the cooling capacity at the air handler is about 1.75 kW less than that at the ammonia/glycol evaporator chiller due to parasitic power gains.