Performance Testing of Unitary Split-System Heat Pump with an Energy Recovery Expansion Device

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

Seasonal Energy Efficiency Rating Improvement Of Residential HVAC Systems Using A Low Power Inverter With A PSC Compressor

Homeowners in the United States can generally choose among three types of air conditioning systems: fixed-speed compressor systems that cycle on and off to deliver an average cooling capacity; fixed-speed / multi-capacity compressor systems with reduced cycling; and variable speed compressor systems that match the cooling load of the household, thereby delivering better temperature and humidity control with higher efficiency and comfort levels. While HVAC systems account for about 45% of the energy consumption in U.S. homes and variable speed compressor systems can achieve significantly higher efficiency, they only account for 10% of the market and systems installed in new buildings mostly remain single speed. This could be explained in part by the initial system cost and the complex electronic circuitry used to vary compressor speed. This paper presents a system solution to improve the Seasonal Energy Efficiency Rating (SEER) of Permanent Split Capacitor (PSC) compressor systems by introducing a low power inverter used only for operation at low capacities. SEER results for 3 tons and 5 tons systems with scroll and rotary compressors are presented. The impact of varying the speed of the PSC outdoor fan on SEER is also discussed