You are here:
EVALUATION OF PERFORMANCE AND COMPOSITION SHIFT OF ZEOTROPIC MIXTURES IN A LORENZ-MEUTZNER REFRIGERATOR/FREEZER
Citation:
Baskin*, E., N D. Smith*, F. R. Delafield, AND M. W. Tufts. EVALUATION OF PERFORMANCE AND COMPOSITION SHIFT OF ZEOTROPIC MIXTURES IN A LORENZ-MEUTZNER REFRIGERATOR/FREEZER. ASHRAE TRANSACTIONS 105(PT.1):41-51, (1999).
Description:
Results from previous testing of this refrigerator/freezer (R/F) using a 750 Btu/hr compressor and several zeotrophic mixtures revealed a performance enhancement up to 16 percent above that of HFC-134a. In the study presented in this paper, the Lorenz-Meutzner (LM) R/F equipped with a 1060 Btu/hr compressor, two evaporators, and two intercoolers was experimentally tested in an environmental chamber according to Association of Home Appliance Manufacturers/Department of Energy (AHAM/DOE) testing standards using hydrofluoropropane-based zeotropic mixtures. The results are compared to baseline testing with HFC-134a and results obtained using the 750 Btu/hr compressor. HFC-245ca/HFC-152a performed comparable to HFC-134a. HFC-245ca/HC-270 outperformed all zeotrophic mixtures and HFC-134a by at least 11.5 percent. All refrigerant performed better using the larger compressor due to its inherent better efficiency. Refrigerant samples taken during R/F operation revealed substantial composition shifts (e.g., 1 30 percent running composition shift of HFC-134a in the HFC-245ca/HFC-134a mixture). Sand et al. (1992) obtained an approximately 20% energy reduction using steady-state on cycle energy consumption results; comparison was made between CFC-12 and a HFC-32/HCFC-124 mixture. Lorenz and Meutzner (1975), originators of the LM R/F design, states that the following parameters influence the optimum performance of the design: 1) heat exchanger size, 2) capillary tube length, 3) refrigerant charge, and 4) compressor size. This work investigates three of these parameters, capillary tube length, compressor size, and refrigerant charge.