CONVECTIVE HEAT-TRANSFER AND FLOW FRICTION FOR WATER-FLOW IN MICROCHANNEL STRUCTURES

The single-phase forced convective heat transfer and Row characteristi cs of water in microchannel structures/plates with small rectangular c hannels having hydraulic diameters of 0.133-0.367 mm and distinct geom etric configurations were investigated experimentally. The results ind icated that the geometric configuration had a significant effect on th e single-phase convective heat transfer and flow characteristics. The laminar heat transfer was found to be dependent upon the aspect ratio and the ratio of the hydraulic diameter to the center-to-center distan ce of the microchannels. The turbulent heat transfer was found to be a further function of a new dimensionless variable, Z, such that Z = 0. 5 will be the optimum configuration for turbulent heat transfer regard less of the groove aspect ratio. The friction factor or flow resistanc e reached a minimum value as Z approaches 0.5. The turbulent flow resi stance was usually smaller than that predicted by classical relationsh ips, and the Reynolds number for flow transition to fully developed tu rbulent flow became much smaller than the ordinary channel flow. Empir ical correlations were suggested For calculating both the heat transfe r and pressure drop. Copyright (C) 1996 Elsevier Science Ltd.