Abstract
Cooling augmentation using double layered (DL) microchannels separated by rotatable plates is investigated in this work. The analyzed devices of the proposed configuration are (A) the flexible microheat exchanger, and (B) the DL-flexible microchannel device. The moment of the pressure forces on the separating plate is related to its rotational angle through its flexible supports. Energy equations for the flowing fluids are solved numerically using an iterative finite-difference method. Comparisons with obtained closed-form solutions under fully developed conditions are performed and excellent agreement is obtained. It is found that the effectiveness and the heat transfer rate per unit pumping power for the flexible microheat exchanger are always higher than that for the rigid one. Moreover, DL-flexible microchannels devices are found to provide more cooling effects per unit pumping power than rigid ones at flow Reynolds numbers below specific values, and at stiffness number and aspect ratio above certain values. These specific values are found to vary with the magnitude of the heating load. DL-microchannels with rotatable separating plates can be utilized in several applications such as electronic cooling. (C) 2011 Elsevier Ltd. All rights reserved.