DOE EERE Research Reports

"Conventional" electric heat pumps use a single-speed electric motor driving a refrigeration compressor circulating a fluid between hot and cold heat exchangers to absorb or reject heat. In hot summer months they absorb heat from inside the house by evaporating the low pressure working fluid (or refrigerant) at temperatures colder than inside the house, compress the refrigerant to form a high pressure, high temperature vapor that can reject heat outside the building as it condenses. The hot high pressure liquid after condensation is flashed to a cold, low pressure mixture of liquid and vapor inside the building and the cycle is repeated. Heating mode is achieved by using a "reversing valve" that directs the refrigerant in the opposite direction through the circuit so heat is "absorbed" out of doors and "rejected" indoors.

Heat pumps lose efficiency through several mechanisms, including cycling on and off to match building loads and through reduced heat transfer and increased pressure drop when the outdoor heat exchanger "frosts up" during heating-mode. Several projects were undertaken to quantify the performance of air-to-air heat pumps both under controlled laboratory conditions and in field testing in occupied and also unoccupied homes. This work was conducted in conjunction with projects on heat pump dynamic losses (i.e. frosting, defrosting, and cycling), variable-capacity heat pumps, and computer modelling of heat pumps.

Links to Publications:

1. Comparison of Field Performance of a High Efficiency Heat Pump With and Without a Desuperheater Water Heater
2. Comparison of Field Performance to Steady-State Performance for Two Dealer-Installed Air-to-Air Heat Pumps
3. Design Optimization and the Limits of Steady-State Heating Efficiency for Conventional Single-Speed Air-Source Heat Pumps
4. Design Optimization of Conventional Heat Pumps: Application to Steady-State Heating Efficiency
5. A Liquid Overfeeding Military Air Conditioner with a Quench Valve
6. Modeled and Measured Effects of Compressor Downsizing in an Existing Air Conditioner/Heat Pump in the COoling Mode
7. Performance Evaluation of a Low-First-Cost, Three-Ton, Air-to-Air Heat Pump in the Heating Mode
8. Performance Evaluation of a Selected Three-Ton Air-to-Air Heat Pump in the Heating Mode
9. Savings in Energy Consumption by Residential Heat Pumps: The Effects of Lower Indoor Temperatures and Night Setback
10. Summary and Evaluation of Field Performance Data on Unitary Heat Pumps
11. Vapor Compression Heat Pump System Field Tests at the TECH Complex