Research and development of an air-cycle heat-pump water heater. Final report

Technical Report · Mon Oct 01 04:00:00 EDT 1979

DOI:https://doi.org/10.2172/5749191· OSTI ID:5749191

Dieckmann, J. T.; Erickson, A. J.; Harvey, A. C.; Toscano, W. M.

A prototype reverse Brayton air cycle heat pump water heater has been designed and built for residential applications. The system consists of a compressor/expander, an air-water heat exchanger, an electric motor, a water circulation pump, a thermostat, and fluid management controls. The prototype development program consisted of a market analysis, design study, and development testing. A potential residential market for the new high-efficiency water heater of approximately 480,000 units/y was identified. The retail and installation cost of this water heater is estimated to be between $500 and $600 which is approximately $300 more than a conventional electric water heater. The average payback per unit is less than 3-1/2 y and the average recurring energy cost savings after the payback period is approximately $105/y at the average seasonal coefficient of performance (COP) of 1.7. As part of the design effort, a thermodynamic parametric analysis was performed on the water heater system. It was determined that to obtain a coefficient of performance of 1.7, the isentropic efficiency of both the compressor and the expander must be at least 85%. The selected mechanical configuration is described. The water heater has a diameter of 25 in. and a height of 73 in. The results of the development testing of the prototype water heater system showed: the electrical motor maximum efficiency of 78%; the compressor isentropic efficiency is 95 to 119% and the volumetric efficiency is approximately 85%; the expander isentropic efficiency is approximately 58% and the volumetric efficiency is 92%; a significant heat transfer loss of approximately 16% occurred in the expander; and the prototype heat pump system COP is 1.26 which is less than the design goal of at least 1.7. Future development work is recommended.

• Research Organization: Foster-Miller Associates, Inc., Waltham, MA (USA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5749191
• Report Number(s): ORNL/SUB-7226/1
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320101* -- Energy Conservation
Consumption
& Utilization-- Residential Buildings-- (-1987)
APPLIANCES
BRAYTON CYCLE
BUILDINGS
COEFFICIENT OF PERFORMANCE
COMMERCIALIZATION
DATA
DATA FORMS
DESIGN
ECONOMICS
ENERGY CONSERVATION
EXPERIMENTAL DATA
FEASIBILITY STUDIES
GAS APPLIANCES
GRAPHS
HEAT PUMPS
HEATERS
HOUSES
INFORMATION
MARKET
NUMERICAL DATA
PERFORMANCE
RESEARCH PROGRAMS
RESIDENTIAL BUILDINGS
TABLES
THERMODYNAMIC CYCLES
WATER HEATERS