Abstract
Heat transfer was investigated experimentally for high pressure ratio air flow in square minichannels, which were machined on the oxygen free copper block. The sizes of the channels were 0.3, 0.6, 1.0 and 2.0mm, and the length were 10, 20, 50 and 100mm. The pressure ratio was changed widely up to the flow choked at the exit. It was found that the heat transfer coefficient was about 7.3 times greater than fully developed turbulent pipe flow. Experimental result showed that 75 percent of the total heat was transfered in 10 percent inlet portion of the channel.
