Abstract: The paper presents the results of flow boiling heat transfer in the horizontal rectangular minichannel. One of the walls of a minichannel is DC supplied to the single-sided microstructured foil. Liquid crystal thermography was used for measuring the temperature distribution on the plain side of the foil. Flow structures were observed on the enhanced side of the foil contacting fluid in the minichannel; the void fraction of selected cross-sections is based on the analysis of these structures. In mathematical modelling stationary process of heat transfer in glass pane, heating foil and boiling fluid can be described with Laplace equation, Poisson equation and energy equation, respectively. For completeness of the model a corresponding system of boundary conditions was given. The two-dimensional temperature distributions in three listed domains were calculated with Trefftz method. The computational procedure is sequential. In the first step we get the solution for glass, then in heating foil and finally in boiling fluid. The calculated values of temperature in liquid and in heating foil as well as the calculated values of heat flux at the contact of these areas allowed to evaluate the transfer coefficient at the foil-fluid interface. The numerical results contained in the paper proved that Trefftz functions can be successfully used to solve both direct and inverse heat transfer problems which occur in flow boiling in the minichannel.
