Conjugate Heat Transfer Analysis of U-Bend/Turn Microchannel: A Computational Approach

To examine the fluid flow and heat transfer properties of a U-shaped bend microchannel, a three-dimensional single-phase numerical study involving the conjugate effect of heat transfer is analyzed. The hydraulic diameter of the geometry was constant (0.4 mm) and the radius of curvature was varied from 2 to 4 mm. The constant heat flux boundary condition was applied at the bottom of the substrate and a comparative study with a straight conventional microchannel design is presented in terms of the performance evaluation factor. Different flow rates were considered to evaluate the effect of secondary flow in the form of Dean Vortices. Non-dimensional heat transfer parameter such as the average Nusselt number and frictional losses in terms of pressure drop was evaluated and the contours of temperature and velocity were analyzed to elaborate the effect of heat transfer enhancement in the bend microchannel. Higher radii of curvature improved the overall performance of the bend channel. At a lower radius of curvature, the performance of the bend microchannel can be improved with increased pumping power. Due to unavoidable pressure loss in the case of microchannel, it is advisable to use U-bend microchannel at relatively low flow rates and higher radius of curvature.