Local Heat Transfer with Asymmetric Herringbone Tube

Abstract

In order to assemble a high performance fin-tube type heat exchanger, one of the most effective ways is improving the heat transfer performance of the tubes. In the present study we carried out the local condensational heat transfer and pressure drop experiments with refrigerant R410A. Two kinds of test tubes were used in the experiments horizontally, i.e. an asymmetric herringbone tube (AH) and a spirally grooved tube (SG), both having 7.00mm O.D. and 500mm long. With the double-tube test section, the experiments were carried out under the mass velocity of 172 and 257kg/m^2s, the inlet pressure of 2.63MPa. Comparing the case with SG, it is found that the condensational heat transfer coefficient with AH is 1.1 to 3.0 time higher, especially 3.0 times in average quality x=0.9,however the pressure drop increases as the average quality becomes high.