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A Comparison of Flow Condensation HTCs of R22 Alternatives in the Multi-Channel Tube  

서영호 (인하대학교 대학원)
박기정 (인하대학교 대학)
정동수 (인하대학교 기계공학과)
Publication Information
Korean Journal of Air-Conditioning and Refrigeration Engineering / v.16, no.6, 2004 , pp. 589-598 More about this Journal
Abstract
Flow condensation heat transfer coefficients (HTCs) of R22 and R134a were measured on a horizontal 9 hole aluminum multi-channel tube. The main test section in the refrigerant loop was made of a flat multi-channel aluminum tube of 1.4 mm hydraulic diameter and 0.53 m length. Refrigerant was cooled by passing cold water through an annulus surrounding the test section. Data were obtained in the vapor qualities of 0.1∼0.9 at mass flux of 200∼400 kg/$m^2$s and heat flux of 7.3∼7.7 ㎾/$m^2$ at the saturation temperature of 4$0^{\circ}C$. All popular correlations in single-phase subcooled liquid and flow condensation originally developed for large single tubes predicted the present data of the flat tube within 20% deviation when effective heat transfer area is used in determining experimental data. This suggests that there is little change in flow characteristics and patterns when the tube diameter is reduced down to 1.4 mm diameter range. Thermal insulation for the outer tube section surrounding the test tube for the transport of heat transfer fluid is very important in fluid heat-ing or cooling type heat transfer experimental apparatus.
Keywords
Flow condensation; Multi-channel flat tube; R22; R134a;
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