Nucleate pool boiling characteristics of R-124

Abstract

This thesis examines the pool boiling heat transfer characteristics of HCFC-124 and HCFC-124/oil mixtures with up to 10% (by weight) miscible alkylbenzene oil. One smooth and 4 enhanced tubes were tested: a 19 and 26 low integral-fin tube (GEWA-K); a modified finned tube (TURBO-B); and a porous coated tube (HIGH FLUX). The tests were carried out using the procedure used for CFC-114 at the same saturation temperature of 2.2 degrees C. This allowed for direct comparison of the pool boiling heat transfer characteristics between the two refrigerants. The smooth and GEWA-K 19 fin per inch tube performance in pure HCFC-124 and HCFC-124/oil mixtures ranged between 10 to 50% better than in pure CFC-114 and CFC-114/oil mixtures for all heat fluxes. The HIGH FLUC and TURBO-B tubes were similar in performance. With pur HCFC-124, the finned tubes typically provided enhancements in the heat transfer coefficient between 2 and 3 times that of a smooth tube. The HIGH FLUX and TURBO-B surfaces typically provided additional enhancements 2 times that of the finned tubes. with the addition of oil, the heat transfer increased from the smooth and finned tubes by decreased from the HIGH FLUX and TURBO-B tubes.. The HIGH FLUX and TURBO-B tubes therefore exhibited enhancements less than the finned tubes at high oil concentrations and high heat fluxes.