Adjustment calculus and Trefftz functions applied to local heat transfer coefficient determination in a minichannel

The paper presents results of numerical calculations conducted in order to define the heat transfer coefficient in flow boiling in a vertical minichannel with one side made of a heating foil with liquid crystals. During the experiment, we measured the local temperature of the foil, inlet and outlet liquid temperature and pressure, current and voltage drop of the electric power supplied to the heater. Local measurements of foil temperature were approximated with a linear combination of the Trefftz functions. The known temperature measurement errors allowed application of the adjustment calculus. The foil temperature distribution was determined by the FEM combined with the Trefftz functions. Local heat transfer coefficients between the foil and the boiling fluid were calculated from the third-kind condition.