Experimental Investigation on a Vapor Injection Heat Pump System with a Single-Stage Compressor

Abstract

In this study, a heat pump of 10 kW with vapor injection using refrigerant of R410A was developed. A vapor injection pipe connecting a gas–liquid separator at the outlet of the main expansion valve and the suction of a single-stage rotary compressor was designed. The heating performance of this vapor injection heat pump was investigated and analyzed at different compressor frequencies and primary temperatures. The experimental results show that for the heat pump without vapor injection, the heating capacity increased linearly with the compressor frequency, while the heating coefficient of performance (COP) decreased linearly with the compressor frequency for each tested primary temperature. The developed vapor injection technique is able to increase the heat pump system’s heating capacity and heating COP when the injection ratio R falls into the range 0.16–0.17. The refrigerant mass flow rate can be increased in the vapor injection heat pump cycle due to the decreased specific volume of the suction refrigerant. The power consumption of vapor injection heat pump cycle almost remains the same with that of the conventional heat pump cycle because of the increased refrigerant mass flow rate and the decreased compression ratio. Finally, it was found that the developed vapor injection cycle is preferable to decreasing the compressor’s discharge temperature.

Identifying the performance and losses of a scroll compressor with vapour injection and R1234ze(E)

“…The main advantage of this technique is the rise of the capacity by controlling the injected refrigerant mass flow rate 14 . Furthermore, it provides cooling to the compressor, decreasing the discharge temperature 15 and therefore, the operating envelope of the compressor can be expanded, compared to the standard vapour compression cycle. Additionally, the injection technique, especially with liquid refrigerant, decreases the oil temperature leading to better oil performance and reduces oil degradation effects 16 .…”

Water Heating and Operational Mode Switching Effects on the Performance of a Multifunctional Heat Pump

“…From experiments, it is found that the new air-conditioning heat pump system can operate stably and efficiently with a coefficient of performance (COP) of 6.0. Liu et al [15] developed a vapor injection heat pump and investigated the performance of the heat pump under different driving frequencies of the compressor and primary temperatures. It was found that the heating capacity and heating performance of the heat pump can be increased and the discharging temperature of the compressor can be reduced by the vapor injection.…”