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Water-to-Water Heat Pump Using Hydrocarbon and Hydrofluorocarbon Zeotropic Mixtures With and Without an Internal Heat Exchanger.


pdf icon Water-to-Water Heat Pump Using Hydrocarbon and Hydrofluorocarbon Zeotropic Mixtures With and Without an Internal Heat Exchanger. (3410 K)
Payne, W. V.; Silk, E. A.; Domanski, P. A.

NISTIR 6449; 20 p. January 2000.

Available from:

National Technical Information Service (NTIS), Technology Administration, U.S. Department of Commerce, Springfield, VA 22161.
Telephone: 1-800-553-6847 or 703-605-6000;
Fax: 703-605-6900.
Website: http://www.ntis.gov
Order number: PB2000-103324

Keywords:

heat pumps; zeotropic mixtures; refrigerants; hydrocarbons

Abstract:

This investigation overviews the results of an experimental study pertaining to flammable refrigerant alternatives in water-to-water heat pumps for building and home applications. The system studied here used a secondary heat transfer loop to communicate with the indoor space. This isolates the flammable refrigerant in the outdoor section of the unit and demonstrates one configuration that could be accepted in the United States. In contrast to the fluid survey of the initial study (Payne et al., 1999), the present study emphasizes the performance of R32/290, R22, R290, and R22-REF (direct expansion case) in the cooling and heating modes. The vapor compression cycle used an internal heat exchanger added between the liquid and vapor lines. Fluid performance as a function of thermophysical properties and heat transfer characteristics are addressed for each cycle configuration. The heat pump charged with R32/290 had the closest performance to the R22 direct expansion system in the cooling mode. Furthermore, the internal heat exchanger system performance exceeded that of the basic vapor compression cycle configuration. In the heating mode, R290 in the basic configuration had the closest approximation to the R22 direct expansion performance. The application of the internal heat exchanger degraded R29O's performance.