Experimental Investigation of Turbulent Heat Transfer in the Entrance Region of Microchannels

摘要: Within the entrance region of a closed channel, effects on flowfield and heat transfer mechanisms are significant. Where microchannels microdevices concerned, there limited studies into this region, those available for laminar flows. In turbulent regime, where hydraulic resistance is conventionally increased, higher pumping powers required. However, future microscale applications may have need flow data in microchannels. There currently no An experimental investigation has been carried out to explore convection uniformly heated microtubes. The measurement local wall temperatures achieved through use unencapsulated thermochromic liquid crystals, state-of-the-art, nonintrusive thermal-measurement technique. Heat was obtained two stainless steel microtubes, with nominal inner diameters 1.067 0.508 mm, over Reynolds number range 4000 9000. working fluid FC-72, adequate tube entry length provided hydrodynamic development before heating. Local temperature Nusselt values thermal found remain relatively constant considered both microtube diameters. This good agreement conventional pipes.