Single-Phase Liquid Heat Transfer in Microchannels

Abstract

The development of advanced microchannel heat exchangers and microfluidic devices is dependent upon the understanding of the fundamental heat transfer processes that occur in these systems. Several researchers have reported significant deviation from the classical theory used in macroscale applications, while others have reported general agreement, especially in the laminar region. This fundamental question needs to be addressed in order to generate a set of design equations to predict the heat transfer performance of microchannel flow devices. A database is generated from the available literature to critically evaluate the reported experimental data. An in-depth comparison of previous experimental data is performed to identify the discrepancies in the reported literature. It is concluded that the classical theory is applicable to microchannel and minichannel flows. The literature reporting discrepancies do not account for developing flows, fin efficiency, erros in channel geometry measurements and experimental uncertainties. It is further concluded that if all these factors are accounted for, the available data have good general agreement with macroscale theories. A similar approach is presented for pressure drop in microchannels in an accompanying conference paper, Steinke and Kandlikar (2005).