Influence of fin height on heat transfer and fluid flow characteristics of rectangular microchannel heat sink

Heat transfer and fluid flow behavior have been studied numerically in rectangular parallel microchannel heat sinks with varying fin height. Seven different cases have been considered by varying the fin heights from 0.4 to 1.0 mm. Completely closed heat sink (conventional configuration) of 1.0 mm fin height is one of the cases while remaining six heat sink configurations hold open space between fin top surfaces and cover wall. Three dimensional (3D) numerical simulations were carried out for the range of operating parameters where heat flux varied from 100 to 500 kW/m(2) and Reynolds number from 100 to 400. Single phase liquid water flows as coolant in the heat sink to remove heat. Optimization of fin height has been done to achieve maximum heat transfer rate and overall thermal performance of the heat sink. It has been observed that proposed design of the heat sinks facilitate distinct heat dissipation capacity and fluid flow characteristics. Predicted results i.e. temperature distribution, heat transfer coefficient pressure drop and velocity profile clearly reveal that heat transfer increases with increasing fin height however, heat sinks of considerably shorter fin heights (0.4 - 0.6 mm) have less potential to transfer heat. Pressure drop also increases with fin height because flow obstruction rises. It has been found that heat sink of fin height 0.8 mm exhibits maximum heat transfer which is even higher than fin heights of 0.9 mm and 1.0 mm (completely closed heat sink). Net convective surface area and typical flow behavior caused by available open space have been identified as major reasons to influence the overall thermal performance of the proposed heat sinks. (C) 2019 Elsevier Ltd. All rights reserved.