Forced convection condensation of R113, R152a and R12 on horizontal flate plate.

Forced convection condensation of pure vapour flowing between two horizontal parallel plates with the bottom plate cooled is analysed numerically. The coupled boundary layer equations for the two phases are solved using an implicite finite difference procedure. The pressure gradient, shear stress, inertia and enthalpy convection terms, and turbulence in the two phases are retained in this analysis. The laminar model and the turbulent models of Fletcher [19] and Koyama et al. [20] are compared for condensation of R113. The mean heat transfer coefficients predicted with the model of Fletcher [19] are in good agreement with the experimental results of Lu and Suryanarayana [18]. The thermal performances of R152a and R12 are also compared. For the condensation of R152a, the pressure drop is 18% smaller and the mean heat transfer coefficients are 24% higher compared to those of R12. These results are in line with the experimental work of Cheng and Tao [12]. The influence of the temperature difference and inclination of the plate on the condensate film thickness are also reported. The results of the present calculations for the condensation of R12, R152a and R113 are represented by a non-dimensional equation.