Author : Kshash Murtadha, Talib
journal of kerbala university,
2007, Volume 3, Issue 4, Pages 111-116
As a result of the Montreal protocol (UNEP, 1987) that limits the production of ozone-depleting refrigerants, manufacturers are searching for alternatives to replace the R12 that is presently used in domestic refrigerator-freezers. Before an alternative can be selected, several issues must be resolved. Among these are energy impacts system, compatibility, cost, and availability. In an effort to determine the energy impact of some of the alternatives, energy consumption tests were preformed in accordance with section 8 of the Association of Home Appliance Manufacturers (AHAM) standard for household refrigerators and household freezers (AHAM, 1985). The results are presented for a 9 ft3 (0.2548 m3) top-mount refrigerator-freezer with static condenser using the following refrigerants: R12, R290/R600a, R134a/R22, and R134a. All refrigeration components remained the same throughout the tests, except that the length of the capillary tube, compressor size, and the amount of the charge were changed for each refrigerant. The experimental results from AHAM test obtained with the same compressor used with R12 indicated that the hydrocarbon mixture of R290/R600a at 61% mass fraction of R290 showed a (34-)% increase in energy efficiency and a faster cooling rate as compared with R12. On another side the R134a/R22 mixture with 0.48 mass fraction of R22 result was more promising (12% lower energy consumption) relative to R12 with changes to refrigeration system, such as a different capillary tube and compressor. Meanwhile the R134a was less promising (7.5% higher energy consumption) using different capillary tube and compressor size as compared with R12. It is noted that the test results are only an initial step in determining a replacement for R12. Further analysis should be performed to determine long-term effects on compressor life and operation over a wide range of ambient temperature.