Analysis of a New Super High Temperature Hybrid Absorption-Compression Heat Pump Cycle

Abstract

Utilization of high-temperature energy in industrial production processes is often exhausted by huge low-temperature waste heat without recovery. Thus, energy efficiency is quite limited. Heat pumps are widely used as a high-efficiency waste heat recovery system and are divided into vapor compression cycle, driven by electricity, and absorption type, driven by steam or hot water. However, compression heat pumps are quite difficult to reach more than 100 °C due to the temperature and compression limits of compressors and the working medium. Meanwhile, the COP (coefficient of performance) of an absorption heat pump is quite low due to the thermodynamic cycle characteristics. In order to increase the outlet temperature and COP significantly, a new type of compression-absorption hybrid heat pump cycle is presented and simulated. Compared with traditional cycles, this heat pump can reach the heat sink temperature of 200 °C with a highly satisfactory COP. This heat pump could reach the optimal COP of 3.249 when the pressure ratio of the compressor is 6.5, the coupling temperature of the low-pressure stage is 55 °C and the coupling temperature of the high-pressure stage is 73 °C. Exergy analysis shows that evaporators and condensers show better efficiency. This heat pump could be promising in different kinds of heat recovery.