Eur. Phys. J. Appl. Phys. 86, 30902 (2019)
https://doi.org/10.1051/epjap/2019190126

Regular Article

Effects of vapor injection modes on the heating performance of heat pumps^★

¹ Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, 300134 Tianjin, PR China
² Guangzhou Enthalpy Energy Saving Technology Ltd. Co., 511400 Guangzhou, PR China
³ School of Engineering, James Clerk Maxwell Building, Peter Guthrie Tait Road, EH9 3FD Scotland, UK

^* e-mail: lbtjcu@tjcu.edu.cn

Received: 12 April 2019
Received in final form: 12 June 2019
Accepted: 13 June 2019
Published online: 29 July 2019

Abstract

Heat pumps are widely investigated for their versatile use in a wide range of applications. In this study, three types of heat pumps were experimentally compared. These heat pumps include an one-stage without injection vapor heat pump, an one-stage injection vapor heat hump and a two-stage injection vapor heat pump with an economizer. The results showed that the heating capacity of all three variants of heat pumps decreases with the decrease of the evaporation temperature. However, the attenuation ratio of the heating capacity is found to be different from one pump to another. On the one hand, the largest attenuation rate is found to be 68.84% for evaporating temperatures ranging from −1 °C to −23 °C and for the case of one-stage heat pump. On the other hand, the smallest attenuation rate is found to be 31% for the two-stage injection vapor heat pump in the same temperature range. It is worth noting that the heating efficiency is improved by the amount of vapor injection, nevertheless, there is a maximum value due to the limitations of the economizer. The two-stage injection vapor heat pump can exhibit an enhanced heating efficiency of 127% compared to the one-stage without injection vapor heat pump and 13% compared to the one-stage injection vapor heat pump for an evaporating temperature of −23 °C.