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ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

LOW REYNOLDS NUMBER LIMIT OF HEAT TRANSFER ENHANCEMENT FOR PHASE CHANGE MATERIAL SLURRY FLOW IN MICRO/MINI CHANNELS

Get access (open in a dialog) DOI: 10.1615/IHTC13.p17.200
12 pages

要約

There are many heat exchanger applications where the heat-transfer rate to fluid pumping power ratio has to be maximized to achieve both the high thermal efficiency and cost effectiveness. Our recent numerical study involving Phase-Change-Materials (PCM) particles in micro-channels revealed significant heat transfer enhancement, provided that an optimal balance among the Reynolds number, particle size, tube length and heat flux is achieved. It has been observed that as the Reynolds number decreases the effectiveness factor (compared to water without PCM) increases and the heat transfer rate to fluid pumping power ratio increases, which is also true if the concentration of PCM increases. The findings, however, were limited to the concentration of less than 30%. In this study we focus on the heat transfer enhancement effects for very low Reynolds number (Re, < 50) and high PCM concentration slurry flow (50% − 70%). While both numerical and experimental investigations are carried out, the experiment results are presented with a limited range of validation for the simulation results. In experiments, a PCM slurry fluid is created by using the relative high-speed jet flow to form a milk-like suspension flow (emulsion). With preliminary experimental confirmation, simulation results show the existence of an optimal operating range for low Reynolds numbers and high PCM concentrations, which could be used for the design condition at least at the same level of heat transfer enhancement as those at higher Reynolds numbers, yet with a higher heat-transfer rate to fluid pumping power ratio.