Performance Improvement of Absorption Heat Pump

Abstract

Simulations and experimental investigations on the basic absorption heat pump indicate that the heating performance (i.e., the heating capacity as well as the heating efficiency) deteriorates significantly at low ambient or low driving source temperatures. In addition, the heating efficiency stays stable or even slightly decreases when the driving temperature is higher than a certain value, leading to a waste of high-temperature heat sources. To extend the applicability and increase the efficiency, the absorption heat pumps are improved by means of advanced cycles. Different advanced cycles for theoretical improvement for lower ambient or lower driving temperatures are compared, with the compression-assisted cycle being the best solution. A prototype of compression-assisted absorption heat pump is developed and measured, indicating great potential under worse conditions. For higher driving temperatures, the generator absorber heat exchanger (GAX) cycle is studied to realize internal heat recovery and thus significantly enhance efficiency. The GAX cycle degrades to a single-effect cycle under worse conditions. Therefore, the compression-assisted GAX cycle is proposed to extend the applicable temperature range for the GAX effect. Year-round energy performance has been analyzed for all the basic and advanced cycles to identity the energy saving potentials. The advanced heat pump cycles can further improve the applicability and efficiency of the novel absorption heating technology.