HEAT TRANSFER ENHANCEMENT IN NANOFLUID SUSPENSIONS

摘要

The investigation into possible applications of the thermal wave conduction theory to explain the spectacular enhancement of heat flux by a factor of between 1.4 to 2.5 in nanofluid suspensions is presented. While other possible explanations have been proposed to settle this discrepancy they were not investigated into sufficient detail for providing a definite answer and they all apply at the nano-scale level rather than bridging between the nano-scale effects and the macro-system investigated. The possible mechanisms proposed so far are Brownian motion, liquid layering at the liquid/particle interface, ballistic phonon effects, nanoparticle clustering as well as convection and wave effects. Furthermore, most available methods for measuring thermal conductivity assume and make use explicitly of the Fourier mechanism of heat transfer. If somehow the nano-level heat transfer effects impact profoundly on the resulting heat flux at the macro-level, possibly via wave phenomena, the whole concept behind the measurement device might be flawed. The present paper presents a possible way by which the transitions from nano-scale via the micro-scales towards the macro-scale occur, hence bridging the gap from nano devices to macro systems performance.