Yang Xiaoxi

Forced convective condensation of nonazeotropic refrigerant mixtures in horizontal annulus with petal shaped fin tubes

In this paper, condensation performance in horizontal annulus was compared with a smooth tube, one Saw-Tooth Finned tube (STF tube), four Petal Shaped Fin tubes (PF tubes), using R113, R11 and their mixtures (vapor molar fractions of R11 at the test section inlet were 0.384, 0.588 and 0.809) as working fluid. The mass flux at the test section ranged from 15–220 kg/m2s. Camera and video camera were used to shoot the flow pattern and condensation phenomena.In this paper, condensation performance in horizontal annulus was compared with a smooth tube, one Saw-Tooth Finned tube (STF tube), four Petal Shaped Fin tubes (PF tubes), using R113, R11 and their mixtures (vapor molar fractions of R11 at the test section inlet were 0.384, 0.588 and 0.809) as working fluid. The mass flux at the test section ranged from 15–220 kg/m2s. Camera and video camera were used to shoot the flow pattern and condensation phenomena.The condensation transfer coefficient (hc) of mixtures were considerably lower than those of pure fluid, and did not change linearly with composition. The maximum degradation of measuredhcfrom the ideal value were 23% for the smooth tube, 65% for STF tube, 67% for PF tubes, which occurred in the composition range of 0.4–0.6 vapor molar fraction of R11.For the condensation of mixture, R11 molar fraction from 38% to 81%, the PF tubes had the highest value ofhc, which were 10–25% higher than those of STF tubes, and 480–580% higher than that of smooth tube, because the petal shaped fins of PF tubes could promote strong turbulence in the two phase flow, and reduce the mass transfer resistance.