Toward a better understanding of friction and heat/mass transfer in microchannels - A literature review

A critical review of published results is presented, to provide a better understanding of microchannel transport phenomena, together with the framework for future research. The main conclusions are (1) the onset of transition to turbulent flow in smooth microchannels does not occur if the Reynolds number is less than or equal to 1,000; (2) the Nusselt number varies as the square root of the Reynolds number in laminar flow; and (3) satisfactory estimates of transfer coefficients, within the accuracy of experimental errors, can be obtained by using either experimental results for smooth channels with large hydraulic diameter or conventional correlations.