2017 Volume 34 Issue 3 Pages 211-221
This study was conducted to investigate the characteristics of condensation heat transfer and frictional pressure drop of non-azeotropic mixture R32/R152a inside a horizontal internally helical-grooved small-diameter tube with equivalent inner diameter of 3.48 mm. The condensation heat transfer coefficients and frictional pressure drops were measured in the range of mass velocities from 100 to 400 kg/(m2s), and at an average saturation temperature of 35 °C. In order to study the effect of grooves on the condensation characteristics of non-azeotropic refrigerant mixture, the heat transfer coefficients and frictional pressure drops inside the helically grooved small-diameter tube were compared with those of a smooth small-diameter tube of same diameter. The frictional pressure drop was not affected by non-azeotropy, and it could be estimated from the previous correlation. And the heat transfer coefficient of R32/R152a was greatly decreasing compared with that of R32 and R152a at the lowest mass velocity. The enhancement ratio of heat transfer by the internally helical-grooves was large at low wetness region, and it is small at high wetness region.
