Conference Year



Energy Recovery, Heat Pump, Turbine, Nozzle, R410A


Due to the rising demand of using energy resources more efficiently, the HVAC&R industry is constantly facing the challenge of meeting strict energy consumption requirements. This paper presents a study that focuses on improving the efficiency of a residential split-system vapor compression heat pump using R410A as the refrigerant. R410A, when used as any sub-critical refrigerant in a vapor compression cycle, has a meaningful difference in potential energy savings when using a practically achievable partially isentropic expansion instead of an adiabatic expansion. As a result, there is a significant potential for efficiency improvements by replacing the expansion valve with a work-generating device - an energy recovery expander. The expander functions by using a nozzle to convert enthalpy and pressure of the refrigerant to a high speed flow. The nozzle is designed to ensure refrigerant phase change and accelerate the flow into the impeller of a micro-turbine. The rotating turbine impeller is connected to an internal generator which generates electrical energy. This electrical energy is used in the system to augment the power into the air conditioner’s indoor fan motor. The expander enables the realization of decreased power consumption and increased evaporator cooling capacity. The expander has been implemented into a 5-ton split system heat pump and tested in both heating and cooling modes. The respective heating seasonal performance factor (HSPF) and seasonal energy efficiency ratio (SEER) values have been calculated for the baseline unit and then compared to those with the energy recovery expansion device. The rated values have been experimentally determined based on the standard test procedure regulated by ASHRAE 210/240.The test results will be reported in this paper.