تحليل ساختاري جريان و انتقال حرارت در ميكروكانال هاي جاذب حرارت

چكيده انگليسي :

91 Constructal Design of Heat and Fluid Flow in Micro channel Heat Sinks Morteza Sharifhasan m sharifhasan@mech iut ac ir 12th March 2011 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Mohammad Reza Salimpour salimpour@cc iut ac irAbstractThe fast development in computing technology has led to the miniaturization and density integration ofelectronic devices But this miniaturization involves more heat generation per unit area Consequently theworking temperature of the electronic components may exceed the desired temperature level Since theperformance of equipment has a direct relationship with its temperature it is important to keep it at anacceptable temperature level Many ideas have been suggested to improve the cooling technology ofelectronic components with high heat flux generation and compact size Among these ideas micro channelheat sinks drew more attention because of high heat transfer coefficients and low coolant requirements Foroptimization of micro channel heat sinks different algorithms and methods have been used One of thesemethods is the constructal theory Electrokinetic effects are important for micro and nano scale transportapplications so they should be considered First part of the thesis is about the geometric optimization of anarray of circular and non circular ducts As optimal dimensions were independent of the array configuration the numerical simulation was performed on a unit cell Numerical optimization for circular square andisosceles right triangle cross sections of channels was performed Based on the results of this investigation some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transferper unit volume In addition to examining the effect of pressure drop on these parameters it was showed thatamong the different geometries of this study square cross section has the most efficiency for a givenvolume The second part reports the numerical geometric optimization of three dimensional micro channelheat sinks with rectangular elliptic and isosceles triangular cross sections The cross sectional areas of thementioned micro channels can change regarding to the degrees of freedom i e the aspect ratio and the solidvolume fraction Actually the purpose of the geometric optimization is to determine the optimal values ofthese parameters in such a way that the peak temperature of the wall is minimized The effects of solidvolume fraction and pressure drop upon the aspect ratio hydraulic diameter and peak temperature of thementioned micro channels are investigated Moreover these micro channel heat sinks are compared witheach other at their optimal conditions Considering the constraints and geometric parameters for theoptimization of the present study it was revealed that the micro channel heat sinks with rectangular andelliptic cross sections have similar performances while micro channels with isosceles triangular cross sections show weaker performances The optimal shapes of all three kinds of the channels were achievednumerically and compared with the approximate results obtained from scale analysis which good agreementswere observed In the third section in addition to the external structure internal structure of the micro channelwas allowed to vary In fact in this section the optimum possible geometry of the micro channel heat sinkwas acquired numerically by considering another degree of freedom of the micro channel heat sink It wasnoteworthy that the effect of variation of coolant fluid thermophysical properties on the characteristics offluid flow and heat transfer was also considered Finally the effect of Electrokinetic on the aspect ratio channel hydraulic diameter and peak temperature was investigated Keywords Constructal non circular micro channel heat sink optimal shape Electrokinetic

شريف حسن، مرتضي

تحليل ساختاري جريان و انتقال حرارت در ميكروكانال هاي جاذب حرارت

ميكرو كانال غير دايره اي , شكل بهينه , ميدان الكتروسينتيك