A new simplified model for condensation heat transfer of zeotropic mixtures inside horizontal tubes

Simple and accurate prediction models are highly demanded for industrial design of heat exchangers using refrigerant mixtures. This paper presents some data taken during condensation of R32/R1234ze(E) and proposes a new method to predict condensation heat transfer coefficient of zeotropic mixtures inside horizontal tubes. The method is developed based on the heat transfer model by Cavallini et al. (2006) for pure fluids by including additional heat transfer resistances during zeotropic mixtures condensation. The heat transfer resistances are modified from the Bell and Ghaly (1973) method by considering the effect of interfacial roughness and non-equilibrium phenomena, following the approach by Del Col et al. (2005). This new model is easy to implement and requires low computational effort. The predicted results by the model show a satisfactory agreement with experimental data covering various mixtures and a wide range of working conditions.