Experimental Investigation of Low Flow Rate, Low Pressure Drop and Heat Transfer in Micro-Channel

The objective of the current experimental program is to generate data for liquid flow through micro-channels. The channel dimensions are 0.9 mm deep x 0.5 mm width. Rectangular seven micro-channels each of 70 mm long were cut on a stainless steel substrate (100 mm x 100 mm x 10 mm) by Electro Discharge Machining (EDM) technique. Covering the top with another plate formed the channels. The liquids used were ethanol and methanol as flow media. Pressure drop and flow rate data were measured and used as raw data to evaluate friction factors in the micro-channels. Transitions occur at lower Reynolds number (Re ~1200) than that in normal channels. Transition region lies in the range 1200 < Re < 2500. Transition was identified as the discontinuity in friction factor-Reynolds number data. Analysis of friction factor vs Reynolds number relation indicates those friction factors is same in the laminar region and lower than that in the turbulent region of normal channels. Temperature data were used to evaluate Nusselt number only with methanol flow. In the absence of enough data, that generalised conclusion is not stated about the dependency of channel dimension and flow media on friction factor and Nusselt number.