Heating and Cooling Feasibility of Absorption Heat Pumps Driven by Evacuated Tube Solar Collectors: An Energy and Economic Analysis

Abstract

Thermal compression-driven heat pump plants usually use solar collectors only providing direct heating when possible and low-temperature (but higher than outside air) cold sources for the heat pump evaporator otherwise. At the same time, solar collectors drive absorption chillers only during summer. In this paper, the possibility of employing evacuated tube collectors to drive an absorption heat pump that operates in summer as a chiller was evaluated from both energy and economic points of view. The ground and solar energy at low temperature were used as cold sources. The ground can be recharged by the cooling of the absorber/condenser in the summer and by solar energy during the mid-seasons. The yearly operation analysis in two different climates here proposed also considered also the utilization of suitable storage capabilities varying the size of the ground probes, solar field, and Generator Tank. A primary energy ratio of 4.75 in a cold and cloudy climate and of 5.9 in a warmer and clearer sky climate was obtained in the best plant con-figuration. An economic analysis on the actual investment costs was presented. The final evaluation considered a cost reduction on the basis of recent price lists available on the Asian market.