Thermohydrodynamic characteristics of two-phase flow in a heated capillary

Two-phase laminar flow in a heated capillary slot, driven by liquid evaporation from the interface, is investigated and a quasi-one-dimensional model is proposed. The model takes into account the multistage character of the process as well as the affect of capillarity, frictional and gravity forces on the flow development. The theoretical description of the phenomenon is based on the assumption of uniform distribution of hydrodynamic and thermal parameters over the cross-section of the liquid and vapor flows. With this approximation, the mass, thermal and momentum equations for the average parameters are obtained. These equations are solved to determine the velocity, pressure and temperature distributions along the capillary axis, the shape of the interfacial surface for various geometrical and regime parameters as well as various physical properties of the liquid and vapor. The effect of the microchannel size, initial temperature of the cooling liquid, wall heat flux and gravity on the flow are considered.