FORCED-CONVECTION HEAT-TRANSFER OF SINGLE-PHASE BINARY-MIXTURES THROUGH MICROCHANNELS

Experiments were conducted to investigate the single-phase forced conv ective heat transfer characteristics of binary mixtures (water and met hanol) flowing through microchannels having hydraulic diameters of 0.1 33-0.357 mm. The experimental measurements indicated that laminar heat transfer ceased at a lower Reynolds number bound of 70-400 depending upon the flow conditions and that fully turbulent convective heat tran sfer was achieved at a Reynolds number of 200-700 depending on the hyd raulic diameter of the microchannel. The transition Reynolds number an d transition range diminished with reductions in the microchannel dime nsions. The geometric parameters, particularly the hydraulic diameter and aspect ratio H/W, were found to have a significant effect on the f luid flow and heat transfer characteristics. In addition, the effect o f the aspect ratio on the convective heat transfer varied as a functio n of the mole fraction of the mixture. For smaller mole fractions of t he more volatile component, the heat transfer was augmented, reaching a maximum value at a characteristic mole fraction. The experimental re sults also indicated that the region in which the heat transfer was au gmented was extended as the mass flow rate through microchannels incre ased.