Investigation of a small width Heat-Sink with considerations for use with Thermo Electric Generators
Author
Kuur, Lars
Term
4. term
Education
Publication year
2011
Submitted on
2011-05-31
Pages
42
Abstract
Specialet undersøger, hvordan mikrokanaler—meget små strømningskanaler—kan bruges sammen med termoelektriske generatorer (TEG'er), som omdanner temperaturforskelle til elektricitet. Der gives et overblik over den aktuelle udvikling på systemniveau for TEG'er og metoder til at vælge et effektivt kølelegeme (heat sink). Der gennemføres forsøg i en minikanal for at studere strømning og varmeoverførsel i små skalaer. To tilgange anvendes: (1) en integral metode, der estimerer den samlede varmeovergang (UA) og sammenligner standardkorrelationer med det målte gennemsnitlige Nusselt-tal; og (2) et nyt optisk setup, der kombinerer Particle Image Velocimetry (PIV) og Planar Laser-Induced Fluorescence (PLIF) for direkte og ikke-invasivt at kortlægge lokale strømnings- og temperaturfelter med henblik på at bestemme lokale Nusselt-tal. Studiet viser, at de termiske og hydrodynamiske grænselag kan opløses, men ikke med tilstrækkelig præcision til at fastlægge Nusselt-tallet pålideligt. Der gives flere forslag til at forbedre målenøjagtigheden.
This thesis explores how microchannels—tiny flow passages—can be used with thermoelectric generators (TEGs), which convert temperature differences into electricity. It reviews current system-level TEG designs and methods for selecting an effective heat sink. Experiments on a mini-channel were carried out to study flow and heat transfer at small scales. Two approaches were used: (1) an integral method that estimates overall heat-transfer capacity (UA) and compares standard correlations with the measured average Nusselt number; and (2) a new optical setup combining Particle Image Velocimetry (PIV) and Planar Laser-Induced Fluorescence (PLIF) to directly and non-invasively map local flow and temperature fields, aiming to obtain local Nusselt numbers. The study shows that thermal and hydrodynamic boundary layers can be resolved, but not with enough precision to reliably determine the Nusselt number. Several avenues for improving measurement accuracy are proposed.
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