Analytical and numerical studies on macro and micro scale heat sinks for electronics applications

Abstract

From the practice in computer industry the standard approach for electronics cooling is fan-cooled heat sinks. We developed thermal models for forced convection heat sinks. An Intel Pentium ill chip has been adopted as a preliminary design case to develop necessary equations. We found the heat dissipated from the aluminum heat sink, based upon different modes of airflow over the fins. We also considered radiation heat transfer. We performed transient heat transfer analysis to determine the time to attain the steady state temperature for the whole system for macro and micro scale also. Next, we refined our one-dimensional analytical convection analysis using the numerical analysis. This was done using the computational fluid dynamics code Fluent to obtain accurate velocity fields over the fins. Using these improved velocities, convective heat transfer coefficients were computed. Next, we have miniaturized the processor chip size to the micrometer scale and have designed a heat sink based upon the models we have developed. Calculations of mean free path and Knudsen number shows the continuum theory for air still holds for our designed micro-channels. Equations for natural convection heat sinks are also explored as a part of this study. In the microscale study, we did forced and natural convection analysis.