CONDENSATION HEAT TRASNFER IN FLATTENED MICROFIN TUBES HAVING DIFFERENT ASPECT RATIO
In this study,condensation heat transfer coefficients of R-410A were obtained in flattened microfin tubes (aspect ratio=2,4,6) made from 7.0 mm outer diameter round tubes.The test range covered saturation temperature 45℃,heat flux 10 kW/m2K,mass flux 100~400 kg/m2s and quality 0.2~0.8.Results showed the effect of aspect ratio on condensation heat transfer coefficient was dependent on the flow pattern.For annular flow,the heat transfer coefficient increased as the aspect ratio increased.For stratified flow,however,the reverse was true.Comparison with the smooth tube counterpart suggests that annular-stratified transition occurs at larger mass flux for the microfin tube.The enhancement ratio ranges from 1.5 to 2.6.Higher enhancement is obtained at G=200 kg/m2s for aspect ratio of 4 and 6,where microfin tube is expected in annular flow regime whereas smooth tube may not.The pressure drop increased as aspect ratio increased.Similar to heat transfer,larger penalty ratio is obtained at G=200 kg/m2s.
BYUN H.-W KIM N.-H LEE E.-J SIM H.-M
Dept.of Mechanical Engineering,Univ.of Incheon,Incheon,Korea
国际会议
西安
英文
1-8
2012-08-26（万方平台首次上网日期，不代表论文的发表时间）