Study of the axial heat conduction in parallel flow microchannel heat exchanger

Abstract

In this paper the axial heat conduction in an isosceles right triangular microchannel heat exchanger is numerically investigated, for laminar, 3D, incompressible, single-phase, steady state flow. The behaviour of axial heat conduction in the separating wall under different conditions is studied. The solution was obtained by solving the continuity and Navier–Stokes equations for the hot and cold fluids by using the pressure-correction method to obtain the velocity distribution, and then the energy equations were solved for the two fluids and the separating wall simultaneously to obtain the temperature distribution. The governing equations are discretized using finite-volume and the hybrid differencing scheme with FORTRAN code was used. Various parameters that can have effect on the axial heat conduction were investigated.The results showed that, the axial heat conduction plays an important role in a parallel flow microchannel heat exchanger and the factors affecting the local and average axial heat conduction are; Reynolds number (Re), thermal conductivity ratio (Kr), hydraulic diameter (Dh), thickness of separating wall (ts) and channel volume. Increasing of Re, Kr and ts leads to an increase in the axial heat conduction while increasing of Dh and channel volume leads to a decrease in the axial heat conduction.