Condensation in minichannels: experimental investigation and numerical modelling

This paper presents an overview of the most recent research works on condensation heat transfer inside minichannels with halogenated refrigerants. The first part is focused on the experimental results available in the scientific literature and the effect of the main parameters (channel diameter, mass velocity, vapour quality, saturation temperature, heat flux) on convective condensation is discussed. In particular the effect of channel shape is treated, showing that at low mass velocity some peculiar characteristics of microscale condensation can be observed. In the second part, numerical models of condensation in minichannels are presented. These models should be able to simulate the heat transfer process resolving the momentum and energy equations and without any empirical input. One important feature of numerical modelling is to provide an insight on the heat transfer mechanisms that may be difficult to get from the experimental investigation. On the other hand, it should be noticed that such numerical models, due to the heavy computational effort required, are still far to be widely applied in heat exchanger design.