Study Of Flow And Heat Transfer Characteristics In Small Rectangle Channels

With the development of science and technology, electronics, machinery and other fields are developing in the direction of miniaturization and micromation. Cooling requirements of such products have keep rising. Microchannel heat exchanger with the feature of small in size and power in heat transfer has become major cooling equipment after miniaturization and micromation. And the performance study has become one of hot spots to domestic and overseas scholars.Flow and heat transfer characteristics in small rectangle channels with equivalent diameter ranging from 0.633 to 1.079 mm were studied both experimentally and numerically in this paper. Liquid water was employed as work fluid, with the Reynolds number ranging from approximately 100 to 3000. The experimental results show that transition from laminar to turbulent flow occurred at critical Reynolds numbers about 2000 in the larger channels of the dimensions considered here. And the smaller ones occurred at about 1700, which is earlier than conventional scale. Experimental values of laminar apparent friction coefficient and Nusselt number are in good agreement with numerical values. Finally, the heat transfer of different structure channels were calculated by numerical methods assuming pump power or flow rate is constant, and optimum heat transfer structures were given.