PHYSICAL EFFECTS OF VARIABLE FLUID PROPERTIES ON GASEOUS SLIPFLOW THROUGH A MICRO-CHANNEL HEAT SINK

Abstract

Physical effects induced in micro-convective gaseous slip-flow due to variation in fluid properties arenumerically examined in this paper. The problem is particularly simulated for slip-flow through a micro-channel heatsink (MCHS) having constant heat flux supplied from the wall under hydrodynamically and thermally fullydeveloped flow (FDF) conditions. It is observed that the Nusselt number (Nu) for slip-flow is significantly higherthan the no-slip-flow condition and Nu is significantly affected due to variable fluid properties (VFP). Four differentcases of VFP are studied in order to investigate their effects individually. Pressure and temperature dependentdensity (ρ(p, T)) variation flattens the axial velocity profile in radial direction (u(r)) profile which promotes fastermoving particles close to the wall which considerably enhances Nu. The incorporation of temperature-dependentviscosity (µ(T)) variation marginally enhances Nu along the flow. Incorporation of temperature-dependent thermalconductivity (k(T)) variation highly augments Nu due to higher ρ and higher k fluid near to the wall and theincorporation of temperature-dependent specific heat at constant pressure (Cp(T)) variation reduces Nu due to lower kfluid near to the wall. The investigation also shows that the pressure drop significantly deviates from no-slip to slipcondition. Furthermore, the effects of VFP on the gauge static pressure drop (Δpg) and slip velocity are alsoexamined. The incorporation of µ(T) and k(T) variations trivially affects the Δpg and slip velocity. However, theincorporation of Cp(T) variation significantly affects the Δpg and slip velocity.