Heat transfer modelling of gas–liquid slug flow without phase change in a micro tube

Numerical simulation of gas–liquid slug flow and associated heat transfer without phase change in a micro tube is carried out. The presence of a gas bubble causes recirculating flow inside a liquid slug, and therefore enhances heat transfer. It is shown that the heat transfer rate is strongly dependent on the flow pattern, i.e., the slug length and the flow rate of each of gas and liquid. The whole flow field is modelled as an adherent liquid film, above which the gas and liquid slugs alternately pass. Since the heat capacity and conductivity of gas phase are negligibly small, while the liquid film is sufficiently thin, the overall heat transfer can be deduced as one-dimensional unsteady heat conduction inside the liquid film with a time-dependent heat transfer rate at the interface between the film and the slug regions. We propose a heat transfer model as a function of parameters representing the flow pattern and assess it in comparison with the present numerical results.