Thermal management with localized heating on enclosure’s wall during thermal convection using different fluids

The paper addresses numerically a study on thermal management of a cavity-shaped thermal system providing localized heating at the bottom. For this fundamental study, different fluids namely air, water, ethylene glycol (EG), and nanofluid are considered in a square cavity from the application point of view. The upper halves of the sidewalls, and top wall act as the isothermal heat sink. The heater acts as an isothermal heat source. Four different configurations are studied in this work: (a) Case-1: central heating with one heater (b) Case-2: corner heating with one heater (c) Case-3: corner heating with two heaters of equal length (d) Case-4: central heating with two heaters of equal length. For all the configurations, the total length of heaters is fixed. The other walls are maintained in an adiabatic condition. The finite volume approach is employed to solve the governing differential equations numerically. The simulation is executed for a spectrum of Prandtl numbers covering the most commonly used working fluids, keeping the Rayleigh number and the volumetric concentration of nanoparticles fixed. The streamlines and isotherms are employed for the visualization of flow and thermal field. The transmission of heat by free convection is characterized by the Nusselt number. The irreversibility in the flow domain is studied using the contours of the entropy generation rate. The aim of this work is to find out the heater location and fluid for which the rate of heat transmission is maximum. The results reveal that the maximum heat removal rate occurs for central heating with a double heater (Case-4) and the minimum heat removal rate takes place for corner heating with a double heater (Case-3). It is noted that the heat transmission rate is maximum for nanofluid.