Role of multiple solar heaters along the walls for the thermal management during natural convection in square and triangular cavities

The role of multiple discrete solar heaters have been studied for energy efficiency in the heating of fluids. Current work involves natural convection studies with the various locations of the double heat sources along each side wall of the triangular-design 1 (regular isosceles triangle), triangular-design 2 (inverted isosceles triangle) and square enclosures for various cases (case 1: larger heater in lower half and smaller heater in central half, case 2: larger heater in central half and smaller heater in lower half, case 3: two heaters of identical lengths are located at the central and lower halves) involving various fluids (Pr = 0.015 and 7.2) for various Rayleigh numbers, 103 <= Ra <= 10(5). The thermal mixing and energy flow in the cavities are visualized using the mathematical tool of heatlines. Also, the overall rate of heat transfer in conduction and convection dominant regimes is evaluated using Nusselt numbers (average and local). The case 2 discrete heating configuration is inferred as the optimal heating configuration based on the larger zone of uniform temperature and thermal mixing. Also, the thermal management is significantly improved in triangular-design 2 and square cavities. (C) 2017 Elsevier Ltd. All rights reserved.