Experimental Evaluation of Individual Hotspots of a Multicore Microprocessor Using Pulsating Heat Sources

The present work provides an experimental and numerical procedure to obtain the geometrical position of the hotspots of a microprocessor using the thermal images obtained from the transient thermal response of this processor subject to pulsating stress tests.This is performed by the solution of the steady inverse heat transfer problem using these thermal images,resulting in qualitative heat source distributions;these are analyzed using the mean heat source gradients to identify the elements that can be considered hotspots.This procedure identified that the processor INTEL Core 2 Quad Q8400S contains one hotspot located in the center of its left die and four hotspots located near the lower left corner of its right die,which is consistent with the thermal response obtained for both the stress test applied to each core of this processor and the stress test applied to all of its cores.

Analysis of behaviour of computational model to evaluate performance of heat pipe containing nanofluids

Application of nanofluids in heat pipes usually presents satisfactory experimental results regarding a thermal resistance reduction of the heat pipe.However,the existing computational studies connecting heat pipes and nanofluids lack a deeper discussion regarding the validity of the models currently used for representing the behaviour of a nanofluid in a heat pipe,particularly for unusual base fluids and nanoparticles such as carbon nanotubes or ethylene glycol.Thus,this comparative study presents the results of a set of computational simulations using pre-established equations for modelling a nanofluid in a heat pipe with experimental data from the literature.The results show agreement with the expected behaviour qualitatively and the presented maximum variations between 1.5% and 23.9% in comparison to the experimentally measured average temperatures.Also,the experimentally obtained temperature distribution of a heat pipe could not be reached numerically only with the use of adequate thermal properties,indicating that the boiling phenomenon is more complex than the current model used for computational simulations.Moreover,the existence of an optimal particle volume fraction for using nanofluids in this application could be observed by combining different properties models.