Numerical and Experimental Studies of Liquid and Gas Flow and Heat Transfer in Microchannels and Nozzles

Microchannel fluid flow and heat transfer was first put forward at the beginning of 1980s (1981 and 1982) by Tuckerman and Pease [1, 2], who employed the direct water circulation in microchannels (with channel width of 300 µm and depth of 50 µm) fabricated in silicon chips as a new cooling technology. They were able to reach the highest heat flux of 7.9 MW m-2 with the maximum temperature difference between substrate and inlet water of 71°C. Soon Wu and Little published two papers in 1983 and 1984, reporting their measurement results of the friction factors and heat transfer characteristics of gas flow in microchannel heat exchangers used for micro/miniature refrigerators [3, 4]. Their channels have a width of 130-200 µm and a depth of 30-60 µm. Since then a large number of experimental and numerical studies have been conducted for the flow and heat transfer in microchannels. In the development of measurement techniques, the contributions given by Ho and his coworkers are especially important. They developed micropressure transducers to measure the local pressure in a microchannel and confirmed the nonlinear pressure distribution in uniform microchannel [5-7].