Experimental study on performance of a hybrid ejector-vapor compression cycle

Abstract

Improving the Coefficient of Performance (COP) of the vapor compression refrigeration cycle (VCRC) is one of the primary objectives in the HVAC&R field. In this paper, a hybrid ejector-vapor compression cycle (EVCC) was presented to improve the COP of the vapor compression sub-cycle (VCSC). That is to say, the sub-cooling degree of the VCSC was improved by using the cooling effect of the ejector refrigeration sub-cycle (ERSC). R134a was employed in both sub-cycles. Specific experimental studies conducted were: (1) seeking the relations between the optimal nozzle exit positions and area ratio of the ejector to improve the performance of the ERSC, (2) investigating the influence of the compressor frequency on the capability of the VCSC, and (3) evaluating the effect of the compressor frequency as well as the evaporation temperature of the ERSC on the characteristics of the EVCC. As a result, two significant findings were obtained: (1) the range of optimal NXPs for higher ARs is quite narrow and vice versa for lower ARs, (2) on average, the COP improvement of the EVCC over the VCSC reaches 19.4%.