Apparatus for the Study of Friction and Heat Transfer in Microchannels

摘要

An experimental apparatus was designed to test friction and heat transfercharacteristics of microchannels (diameters of 500 micrometers or less). Two sets of microchannels were tested: a set of nine 508 micrometers square channels and a single 254 micrometers square channel. The laminar friction factor for the 508 mm channels was lower than expected and was Reynolds number dependent. This result was attributed to experimental uncertainty. The turbulent data followed theoretical predictions. The heat transfer data were also lower than expected. Again, this rsult was attributed to experimental uncertainties. The 254 micrometers channel resulted in lower friction factor, but showed the same trends shown in the Moody diagram: laminar, transition, then turbulence. The Nusselt number data were shown to be within 10% of the theoretical predictions. In addition, an analytical model which accurately predicts the heat transfer and friction characteristics for the 508 micrometers rectangular channels tested in this work was developed. The model may be used to predict optimal configurations for future tests. However, the model requires further experimental validation for smaller channel sizes.