Recharging of a Rectangular Microchannel over a Span to Increase Heat Transfer

Abstract

Microchannel have gained immense popularity due to its extensive use in various fields, especially for heat exchangers used to cool the microelectronic chips and also for various other purposes. This project focuses on increasing heat transfer on the conjugate wall by carrying out a mathematical simulation to study the effect on the Nusselt number by the introduction of a fresh flow by a secondary recharging inlet in between the main channel flow. At first a 2-D model representation (i.e. flow between two plates) has been studied to check the viability of the recharging concept through comparison between a simple and recharging case. Proceeding with the 3-D case, numerical analysis has been carried out for three varying geometries (dsf = 1, 2, 4) of microchannel with two Reynold’s number (Re = 500, 1000) variation and 11 different solid materials (ksf = 0.33~702.9) with variable thermal conductivity values. A constant heat flux has been provided at the bottom wall, other walls being kept adiabatic and flow rate is assumed such that the flow is laminar throughout theoretically. It is found that the introduction of a recharging inlet causes an increase in the average Nusselt number which represents an increase in heat transfer thus refining the efficiency of the microchannel. Thus optimum ksf for maximizing Nusselt number is found out in between the two extreme values by plotting the graphs. Added to these the effects of varying geometry on flux and temperature distribution has also been analyzed. Hence, it is seen that, recharging increases the average Nusselt number and also ksf is the key value in deciding the effect of axial condition and thus maximizing the Nusselt number