Constructal design of cavities for intensified cooling performance on heat generating volumes

Abstract

The study of heat conduction in micro systems is a topic of interest as heat generation is a common issue in electronics. This paper will study heat conduction, using finite element simulations of a cross-sectional copper surface with micro channels where the thermal conductivity of the coolant fluid is set to 0.591 W/(m·K), which corresponds to water at 293 K. The simulated models are made using COMSOL Multiphysics 5.2a. Heat Transfer module allows for the study of heat transfer in devices. The bottom and side surfaces of the heat sink are thermally isolated. The top surface is assigned a general inward heat flux of 10 MW/m2. The channel structure is designed following the Allometric law. For a Y-design, 45˚ angles are used between one bifurcation level and the next, and 90˚ for the T-design. A steady state situation is defined, and a laminar flow at constant temperature is designated for the fluid in the channels. Looking at this as a fully developed region with constant surface temperature, the Nusselt number can be considered constant. The heat transfer coefficient assigned to the channels is obtained from calculations related to the channel dimensions and the previously mentioned boundary conditions. The respective Darcy friction factor, pressure drop and nominal pumping power is calculated for each of the designs. The resulting simulations show the diffusion dominated heat conduction of the heated area. The Y-design is shown to be the superior design for heat conduction.