Abstract
Heat transfer characteristics in the developing region of a flat channel with a dimpled surface were investigated experimentally for relatively low Reynolds numbers of Re = 1000 - 5000. Detailed local heat transfer characteristics were measured by the naphthalene sublimation method for two kinds of dimples with different depths. The heat transfer enhancement effect of the dimpled surface was observed in the mean Sherwood number for Re > 3000. In this relatively high Re condition, the high heat transfer regions appeared in the downstream halves of the dimples and the flat surface regions downstream them. Such heat transfer enhancement effect appeared after the second row of the dimples. In lower Re, high heat transfer regions appeared near the downstream edges of the dimples but they were cancelled out by the low heat transfer regions inside the dimples. The dimple with smaller depth was more effective to the heat transfer enhancement in the channel.
