Comparisons of experimental results and prediction methods of supercritical CO2 cooling heat transfer and pressure drop in macro- and micro-scale channels

Abstract

Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.Comparisons of heat transfer and pressure drop experimental data and correlations for supercritical CO2 cooling are presented in this article. First, the physical and transport properties of CO2 at supercritical conditions are discussed and then their influence on heat transfer and pressure drop. Then, comparison and analysis relative to the available heat transfer and pressure drop correlations for supercritical CO2 cooling were done where possible. Noting the lack of all pertinent experimental details required to use the data published in many of the available studies, comments are given on how to reduce and present supercritical CO2 experimental data properly in the future. Simulations by the available heat transfer correlations were performed and the predicted results were compared with each other. Based on the comparisons and analysis, it is recommended that further efforts be made to develop improved heat transfer methods for supercritical CO2 cooling based on a more accurate database in the future. To achieve this, more careful experiments should be done in both macro- and microchannels over a wide range of test parameters, including the effect of oil. In addition, several experimental studies show that the Blasius equation works well for pressure drop of CO2 cooling in the supercritical region. More careful experimental data are still needed to further validate this conclusion.