Water-to-Water Heat Pump Using Hydrocarbon and Hydrofluorocarbon Zeotropic Mixtures With and Without an Internal Heat Exchanger.
Water-to-Water Heat Pump Using Hydrocarbon and
Hydrofluorocarbon Zeotropic Mixtures With and Without an
Internal Heat Exchanger.
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.
1-800-553-6847 or 703-605-6000;
Order number: PB2000-103324
heat pumps; zeotropic mixtures; refrigerants;
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.