Application of the Trefftz Method for Pool Boiling Heat Transfer on Open Microchannel Surfaces

Abstract

In the paper, the results of tests on pool boiling heat transfer on open microchannel surfaces were discussed. Nucleate pool boiling from copper microchannel surfaces was examined using ethanol as a working fluid. Parallel microchannels fabricated by machining were about 0.2 to 0.4 mm wide and 0.2 to 0.5 mm deep. In the mathematical model the heat transfer process was in steady state. The heat transfer in copper block was assumed axisymmetric while the specimen temperature distribution was not. The temperature of the copper block and the specimen were assumed to satisfy Laplace’s equations with adequate boundary conditions. The problem was solved by the Trefftz method with two sets of Trefftz functions. Graphs were used to represent the copper block and the specimen temperature distributions, local values of heat transfer coefficients as a function of the heat flux and fin temperature distribution. Uncertainty analysis was presented.