An efficient finite element procedure for the analysis of cross-flow micro heat exchangers

As an alternative to massive CFD, a hybrid technique, which has the advantage of accounting for all of the three-dimensional features of the flow field, but with a limited computational effort, is used for the solution of conjugate convection-conduction heat transfer problems in cross-flow micro heat exchangers. The key feature of the proposed method is represented by the separate computation of the velocity fields in single microchannels and on the subsequent mapping of such velocity fields onto the threedimensional grid used to solve the thermal problem. The cross-flow micro heat exchangers considered in the paper consist of a number of layers of rectangular microchannels. A parametric study is carried out on the combined effect on crossflow micro heat exchanger thermal performances due to the variation of the microchannel cross-section and of the ratio of solid to fluid thermal conductivity.