Numerical study of a hybrid absorption-compressionhigh temperature heat pump for industrial waste heat recovery

Abstract

The present paper aims at exploring a hybrid absorption-compressionheat pump (HAC-HP) to upgrade and recover the industrial waste heatin the temperature range of 60°C–120°C. The new HAC-HPsystem proposed has a condenser, an evaporator, and one more solutionpump, compared to the conventional HAC-HP system, to allow flexibleutilization of energy sources of electricity and waste heat. In thesystem proposed, the pressure of ammonia-water vapor desorbed in thegenerator can be elevated by two routes; one is via the compressionof compressor while the other is via the condenser, the solution pump,and the evaporator. The results show that more ammonia-water vaporflowing through the compressor leads to a substantial higher energyefficiency due to the higher quality of electricity, however, onlya slight change on the system exergy efficiency is noticed. The temperaturelift increases with the increasing system recirculation flow ratio,however, the system energy and exergy efficiencies drop towards zero.The suitable operation ranges of HAC-HP are recommended for the wasteheat at 60°C, 80°C, 100°C, and 120°C. The recirculationflow ratio should be lower than 9, 6, 5, and 4 respectively for thesewaste heat, while the temperature lifts are in the range of 9.8°C–27.7°C, 14.9°C–44.1 °C, 24.4°C–64.1°C,and 40.7°C–85.7°C, respectively, and the system energyefficiency are 0.35–0.93, 0.32–0.90, 0.25–0.85,and 0.14–0.76.

Key words： absorption compression; hightemperature heat pump; efficiency; industrial waste heat; thermodynamic analysis

Acknowledgements

This work was supported by the Heat-STRESSproject (EP/N02155X/1), funded by the Engineering and Physical ScienceResearch Council of UK.

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