For both numerically and experimentally, effect of gravity on the heat transfer and fluid flow phenomenon of microchannel heat exchangers was presented. The influence was determined by two cases: one with horizontal channels, the other with vertical channels. For vertical channels, the hot water is flowing upward which is against the gravitational field, while the cold water is flowing downward which is in the same direction as the gravitational field. In this study, the difference between the results obtained from horizontal channels and those from vertical ones is negligibly small; the impact of gravity on the fluid through the microchannel heat exchangers was found to be small, with the maximum difference between the two cases being less than 8%. The results obtained from numerical simulation and experimental data are in good agreement. In addition, good agreements were also achieved between the results obtained in the present study and the results obtained in literatures.

Published in 2012