Effect of variation in channels area on the performance of counter flow microchannel heat exchanger

In this paper the counter flow microchannel heat exchanger (CFMCHE) is numerically investigated by solving 3D Navier Stock equations in two fluids and 3D energy equation in two fluids and walls. The axial conduction in the walls and entrance region are taken into consideration. And a new technique is used by using variable cross-sectional area microchannels instead of constant area microchannels to improve the performance of this type of heat exchangers. The variation in channels area is made by inclined only the walls separating the channels which lead to changing the height of channels and keeping its width constant. The idea of using variable cross-sectional area microchannels applied on three channels geometry (square, rectangular and trapezoidal). The results obtained show that, using of variable cross-sectional area channels lead to improve both the hydrodynamic and thermal performance of CFMCHE since it lead to reduce the pressure drop and increase the effectiveness of heat exchanger.