Second law analysis of recharging microchannel using entropy generation minimization method

This work deals with numerical study of entropy generation in recharging and simple microchannel to explore effect of geometrical modification on thermodynamic irreversibility in a system. This work also investigates effects of geometrical and thermo-physical parameters on entropy generation in recharging microchannel system, by varying number of small channels, substrate thickness, channel wall width, channel aspect ratio, substrate material, and applied heat flux. Numerical simulations are carried out by considering water as working fluid with Reynolds number 100-500. Results reveal that recharging microchannel shows maximum 47% reduction in total entropy generation compared to simple microchannel, which indicates that thermodynamic irreversibility is lower in recharging microchannel compared to simple microchannel. Thermal entropy generation in recharging microchannel decreases with increasing number of small channels, channel aspect ratio, and substrate material thermal conductivity, whereas it increases with increasing substrate thickness, channel wall width, and applied heat flux. Moreover, frictional entropy generation in recharging microchannel is invariant with substrate thickness, channel wall width, substrate material, and applied heat flux. These parametric investigations indicate that consideration of entropy generation in microchannel solid substrate during entropy generation analysis is quite important, as it strongly influence entropy generation in a system.