Comparison of heat transfer correlations for single- and two-phase microchannel flows for microelectronics cooling

A comparison of four heat transfer correlations for single-phase and six for two-phase microchannel flows has been conducted, for a Reynolds number range between 300 and 80,000. For this range, the results for single-phase correlations are very close to those for two-phase flow for low mixture quality, although for higher mixture qualities, the two-phase correlations had higher values for the Nusselt number. This means that correlations from several investigations were compared with three different working fluids and equivalent flow conditions. Correlations employing the boiling and/or convective number, along with the Martinelli parameter, were found to be more consistent, while several correlations developed for liquid flows appear to require further study, and potentially modification, prior to use in microchannel flow applications. Although much information has been gained recently, further investigation is required to improve the understanding of heat transfer in single-phase and two-phase microchannel flows.