Performance Investigation of Refrigerant Vapor-Injection Technique for Residential Heat Pump Systems

An 11 kW R410A heat pump system with a two-stage vapor-injected scroll compressor has been developed and tested. A conventional heat pump system with a scroll compressor having the same displacement volume to the vapor-injected scroll compressor has been tested under the same conditions to serve as a baseline. The vaporinjected scroll compressor has been tested with the cycle options of both flash tank and internal heat exchanger configurations. The results show that the vapor-injection technique can effectively increase the system performance for both high ambient cooling application and low ambient heating application. A cooling capacity gain of around 14% with 4% COP improvement at ambient 46.1°C, about 30% heating capacity improvement with 20% COP gain at -17.8°C and about 7% HSPF improvement in U.S. Department of Energy’s northern Region IV climate have been found for the vapor-injected R410A heat pump system as compared to the conventional system.