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A Study of External Condensation Heat Transfer of Flammable Refrigerants  

배동수 (인하대학교 대학원)
하종철 (인하대학교 대학)
유길상 (인하대학교 대학)
정동수 (인하대학교 기계공학과)
Publication Information
Korean Journal of Air-Conditioning and Refrigeration Engineering / v.16, no.6, 2004 , pp. 522-529 More about this Journal
Abstract
In this study, external condensation heat transfer coefficients (HTCs) of flammable refrigerants of propylene, propane, isobutane, butane, DME, and HFC32 were measured on a horizontal plain tube, 26 fpi low fin tube, and Turbo-C tube. All data were taken at the temperature of 39$^{\circ}C$ with a wall subcooling of 3∼8$^{\circ}C$. Test results showed a typical trend that condensation HTCs of flammable refrigerants decrease with increasing wall subcooling. HFC32 had the highest HTCs among the tested refrigerants showing 44% higher HTCs than those of HCFC22 while DME showed 28% higher HTCs than those of HCFC22. HTCs of propylene and butane were similar to those of HCFC22 while those of propane and isobutane were similar to those of HFC134a. Based upon the tested data, Nusselt's equation is modified to predict the plain tube data within a deviation of 3%. For 26 fpi low fin tube, Beatty and Katz equation predicted the data within a deviation of 7.3% for all flammable refrigerants tested. The heat transfer enhancement factors for the 26 fpi low fin and Turbo-C tubes were 4.6∼5.7 and 4.7∼6.9 respectively for the refrigerants tested indicating that the performance of Turbo-C tube is the best among the tubes tested.
Keywords
Flammable refrigerants; Horizontal plain tube; External con-densation heat transfer coefficients(HTCs); Enhanced tubes; Enhancement ratio;
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