2903 (RP-378) -- Experimental Study on Condensation of Refrigerant-Oil Mixtures: Part II — Results of R-12 and R-22 on the External Surface of Single and Multiple Horizontal Plain Tubes ✓ Most Recent

In this, Part II, of the experimental study on condensation of refrigerant-oil mixtures, test results of R-12 and R-22 are presented. 518 test runs are covered here, among them 343 with R-12 and 175 with R-22. The oil used in this study is al kyl benzene-based. The refrigerant vapor, with or without the presence of oil, condensed on the external surface of single and multiple, horizontal plain tubes. For each oil concentration, namely 21A, 4%, 6%, and 8%, tests were conducted at three condensing temperatures, 32.2, 40.6, and 48.9°C (90, 105, and 120 F) for R-12, and two condensing temperatures, 32.2 and 40.6°C (90 and 105 F) for R-22. It was found that the higher the oil-to-refrigerant mass flow ratio, the lower the condensing film coefficient for both single and multiple tubes. A new relationship between the condensing coefficient and the vapor-surface temperature drop has been developed for the multitube case. Empirical equations are given and recommended for the practical design of R-12 and R-22 condensers.

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