Entropy generation in rectangular microchannels

Entropy generation in a rectangular microchannel with fully developed steady gaseous flow at slip flow regime is studied. Two different thermal versions, uniform temperature (H1) and uniform heat flux (H2) on the walls, are considered. Analytically obtained expressions for temperature and velocity fields are used for entropy generation calculations. The effects of rarefaction, geometry, Peclet number Pe and group parameter Br/ω on entropy generation (irreversibility) and local variation of entropy generation are explored. The main findings are; irreversibility decreases with rarefaction regardless of the thermal versions, irreversibility increases with aspect ratio for H1 thermal version and exhibits very little change with aspect ratio for H2 thermal version. For H1 thermal version the points of maximal entropy generation are at the middle of walls. For H2 thermal version entropy generation is generally high at immediate vicinity of walls and decreases by departing the walls toward the centre of the microchannel.