Condensation Heat Transfer Characteristics of a Separate Heat Pipe in Cool Storage Air-Conditioning Systems

The condensation characteristics model of the condensation part of a separate heat pipe in a cool storage air-conditioning system is presented. In this model, the shear stress between gas and liquid two-phase flow is considered. R134a is taken as working medium of the heat pipe. The liquid film thickness, shear stress, and heat transfer coefficient of the heat pipe are calculated. The effect of the shear stress on the film thickness and the variations of the heat transfer coefficient with heat pipe diameter and heat flux are analyzed. Influences of the heat pipe incline angle and heat flux on the heat transfer coefficient are also considered. The results indicate that the liquid film based on this model is thinner and the condensation heat transfer coefficient is larger than that based on the Nusselt model.