Performance analysis of single-stage air source heat pump utilizing indirect vapor injection design

Abstract

This study investigated the performance of a single-stage scroll compressed air source heat pump coupled with a flash tank indirect vapor injection. In the refrigerant circulating piping of the heat pump, an indirect vapor injection piping connecting a flash tank at the refrigerant outlet of a condenser and the suction of a scroll compressor was designed. By the indirect refrigerant vapor injection from the flash tank, the saturation pressure and temperature of the refrigerant (R134a) in the evaporator can be raised and the sub-cooling of the refrigerant at the inlet of expansion valve can be enlarged as well. Thus, energy consumption of the compressor can be reduced and cooling capacity of the evaporator can be boosted. It was found that the suitable amount of indirect vapor refrigerant strongly depends on the operational environmental temperatures. By adjusting the suitable indirect vapor injection volume into the compressor, the performance of the heat pump was enhanced. In this study, a suitable indirect vapor injection volume was found and 5~15% performance increments can be obtained while the heat pump operated under ambient temperatures in a range from 5°C to 35°C.

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

“…Regarding the heat recovery and thermal storage in the heat pump system, the wasted heat ejected from condenser of an air conditioner can be recovered and be used to generate hot water. In the past 70 years, several studies have found that high-performance heat pumps can be employed to achieve energy savings [6][7][8][9][10]. However, these studies have mainly focused on energy savings in terms of the hot water supply.…”

Performance Analysis of High-temperature Two-stage Compression Heat Pump with Vapor Injection Dynamic Control

“…They theoretically showed that increasing the vapor injection pressure increases the amount of vapor injection and the subcooling degree of the refrigeration cycle and enhances the performance of the system. Luo and coworkers (19,20) developed an intelligent strategy for controlling the subcooling degree by sensing the condensation temperature and subcooled refrigerant temperature at the inlet of the expansion valve to dynamically obtain high performance of a heat pump at different condensation temperatures.…”

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

“…Therefore, a vapor compression heat pump system has high efficiency and is considered to be competitive to decrease energy consumption and thus reduce CO 2 emission [5,6]. Continuous efforts with regard to research on more efficient systems have mainly focused on viewpoints using alterative cycles [7][8][9][10] and the use of new refrigerants [7,11].…”

“…In recent years, heat pump systems with vapor injection to the suction port of a single-stage compressor have been recommended as a relatively inexpensive solution for vapor injection heat pump system. Lai et al [10] developed a single-stage air source heat pump with indirect vapor injection piping connecting a flash tank at the refrigerant outlet of the condenser and the accumulator of a scroll compressor. They concluded that the COP increments of 5-15% had been obtained when the heat pump was operated under ambient temperatures ranging from 5 • C to 35 • C. Roh and Kim [13] proposed a novel vapor injection cycle by injecting vapor refrigerant into the accumulator instead of the injection port of compressor.…”