Investigation on the cycle performance of a novel diffusion absorption heat transformer with ejection boost

Abstract

A novel diffusion absorption heat transformer cycle with ejection boost was proposed, and the cycle performance was analyzed by a constructed theoretical model in this paper. The cycle can be carried out with water (H2O) as the refrigerant, lithium bromide (LiBr) as the absorbent, helium (He) as the diffusant, and cyclopentane (C5H10) as the high-pressure fluid. The impacts of six different temperatures on the ejector and cycle performance were evaluated. It was found that increasing the temperature of Generator A and the temperature of Condenser A were both beneficial to the entrainment ratio improvement of ejector with ejector efficiency reduced. The pumping performance of Lifting Tube and system COP were more sensitive to the temperature of Generator B. Under the condition of design temperature, COP of the novel diffusion absorption heat transformer cycle with ejection boost is 0.27, higher than 0.17 in an original diffusion absorption heat transformer. The cycle performance is significantly improved with higher efficiency of diffusant generation and transportation by the employment of ejector. The investigation of this paper makes great sense to the low-grade thermal energy utilization and the stepped utilization of thermal energy.