1Department of Mechanical Engineering, Krishna Institute of Engineering and Technology, Ghaziabad (India).
2Department of Mechanical Engineering, Jamia Millia Islamia, New Delhi (India).
Some experimental results on heat transfer and pressure drop through microchannels evidenced that the classical theory, valid for large sized channels, could be not valid for channels having a hydraulic diameter smaller than 1 mm. Also the transition from laminar to turbulent regime is found to happen to Reynolds number lower than the expected value and this fact is considered a confirmation of the disagreement with the classical theory; in this paper is shown as some analytical analysis of Laminar flow and Heat Transfer through circular Microchannels. The analysis is on flow rate of air (whose temperature varies from 20°C to 50°C) through Microchannels. The flow rate varies from 0.5 liters per hr. to 4 liters per hr. and hydraulic diameter varies from 150 μm to 500 μm. The result shows that for the fix value of flow rate as well as hydraulic diameter of microchannel, the Reynolds number decreases with increase of air temperature. The air temperature also plays a significant role on Nusselt number (Nu) and heat transfer coefficient (h). For a particular value of Reynolds number and hydraulic diameter of microchannel, the Nusselt number attains its least value when the air temperature has its max. value but in case of heat transfer coefficient results are different that is heat transfer coefficient attaint its max. value when the air is at max. temperature for the fix value of Nusselt number and hydraulic diameter of microchannel.
