EXPERIMENTAL INVESTIGATIONS ON CONDENSATION CHARACTERISTICS OF PURE AND MIXTURE REFRIGERANTS OF HFCs IN HORIZONTAL MICRO-FIN TUBES

摘要

The local condensation heat transfer coefficient and local frictional Pressure gradients were evaluated at saturation temperature of 35°C & 40°C respectively, in mass flux range of 200-400kg/m~2-s & vapour quality range of 0.1-0.9 for R134a & R404A respectively, and in mass flux range of 200-300kg/m~2-s & vapour quality range of 0.2-0.8 for R410A using two horizontal tubes with having helix angles, 15° and 18°. The overall uncertainty in the measurement of local heat transfer coefficient and average vapour quality were in the range of ±6-40% and ±3-15% respectively. The local heat transfer coefficients for R134a & R404A ranged from 1095-8797W/m~2-K & 1422-7905W/m~2-K while that of R410A were in the range of 1390- 7255W/m~2-K.Enhancement factors (EFs) for R134a, R404A and R410A were in ranges of 1.2-2.54, 1.15-2.4 & 1.2-2.1 respectively. The frictional pressure gradients obtained for refrigerants R134a & R404A were in the range of 1.3-11.5kPa/m and 0.9-5.8kPa/m respectively and that of R410A was in the range of 1.3- 4.1kPa/m.