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Two-Phase Flow of Two HFC Refrigerant Mixtures Through Short Tube Orifices, Draft Final Report
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The present study presents data for flow of two refrigerant mixtures through short tube orifices. The two mixtures were R3211251134a (23%/25%/52% on a mass percentage basis) and R321125 (50%/50%). The following presents results for the flow of these two refrigerants through short tube orifices of various diameters and lengths of 0.5 in (12.7 mm), 0.75 in (19.05 mm), and 1.00 in (25.4 mm) in a pure form and mixed with various mass percentages of oil.
DescriptionThe need for new refrigerants was established when scientists first realized the ozone depleting effects of CFC and HCFC refrigerants. The chlorine atom in these refrigerants is capable of reaching the upper atmosphere where one chlorine atom can destroy more than 100,000 ozone atoms(Lang1ey 1994). Laws have been enacted to halt the destruction of the ozone layer and force industry to find replacements for the ozone depleting refrigerants. Section 608 of the Clean Air Act (1990) prohibited the venting of ozone depleting refrigerants as of July 1, 1992. In addition the Clean Air Act (1990) also requires the EPA to develop regulations limiting the emissions of ozone depleting refrigerants. Efforts are currently underway to find CFC replacements before the complete phaseout of CFC manufacturing in January of 1996. Much of the effort to replace CFC and HCFC refrigerants has centered on development of refrigerant mixtures that could replace R-22. Before systems can be designed with a new refrigerant (or mixture), thermodynamic and thermophysical properties must first be characterized. An important component in air conditioners is the expansion device. Because of their low cost, several manufacturers have chosen to use short tube orifices for the expansion device in their systems. Designing a system with an orifice requires knowledge of the flow characteristics of short tube orifices. Recent work on orifices has focused on R-12 and R-22 (Kim and O'Neal, 1993a; Aaron and Domanski, 1990; Krakow, 1988; and Mei, 1982). In addition, there are unpublished data on R-134a @m and ONeal, 1993b) and the effect of lubricants on flow characteristics (Kim, 1993; Kim and O'Neal, 1994b).
Payne, W. V.; O'Neal, D. L. (1994). Two-Phase Flow of Two HFC Refrigerant Mixtures Through Short Tube Orifices, Draft Final Report. Energy Systems Laboratory (http://esl.tamu.edu), Texas A&M University; Department of Mechanical Engineering, Texas A&M University. Available electronically from