The understanding of two-phase flow and heat transfer with phase change in minichannels is needed for the design and optimization of heat exchangers and other industrial applications. In this study a three-dimensional numerical model has been developed to predict filmwise condensation heat transfer inside a rectangular minichannel. The Volume of Fluid (VOF) method is used to track the vapor-liquid interface. The modified High Resolution Interface Capture (HRIC) scheme is employed to keep the interface sharp. The governing equations and the VOF equation with relevant source terms for condensation are solved. The surface tension is taken into account in the modeling and it is evaluated by the Continuum Surface Force (CSF) approach. The simulation is performed using the CFD software package, ANSYS FLUENT, and an in-house developed code. This in-house code is specifically developed to calculate the source terms associated with phase change. These terms are deduced from Hertz-Knudsen equation based on the kinetic gas theory. The numerical results are validated with data obtained from the open literature. The standard k-ω model is applied to model the turbulence through both the liquid and vapor phase. The numerical results show that surface tension plays an important role in the condensation heat transfer process. Heat transfer enhancement is obtained due to the presence of the corners. The surface tension pulls the liquid towards the corners and reduces the average thermal resistance in the cross section.

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