G110 HEAT TRANSFER CHARACTERISTICS OF ALTERNATIVE REFRIGERANT-OIL MIXTURES IN A MICROFIN TUBE CONDENSER(Heat exchanger fundamentals)

概要

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Present study investigated the heat transfer characteristics of R-22, and its alternative refrigerant, R-407C mixed with mineral oil (290 SUS) and POE oil (315 SUS) respectively. The test section of micro fin tube contained U-bend and the heat transfer coefficients at the U-bend were also measured. Experimental parameters include an oil concentration varied from 0 to 5%, a mass flux of 100 to 400 kg/m^2s, and inlet quality of 0.5 to 0.9. The heat transfer coefficients of R-407C were smaller by 12-44 % than those of R-22. The heat transfer coefficients in the U-bend had a maximum at 90° point in U-bend. The heat transfer coefficients in a region within the length of 48 times of outer diameter of tube were larger by 22-33% for R-22 and 13-25% for R-407C than the average heat transfer coefficient in the first straight section. The enhancement factors of R-22 and R-407C refrigerant decreased continuously as the sampled oil concentration increased. The enhancement factors of both refrigerants decreased more rapidly as the mass flux decreased and inlet quality increased.
一般社団法人日本機械学会の論文
2000-10-01