A Simulation Study of Enhanced Radiation Cooling on a Radiator with High Emissivity Coating

Abstract

In the vacuum or natural convection, radiation is one of the main heat transfer methods. The structure and surface emissivity of the radiator have important impacts on radiation performances. A calculation model of radiative heat transfer of the rectangular finned radiator was established, and radiative characteristics under different emissivity and different ratios of fin height to fin spacing (H/s) were analyzed. The results showed that increasing the emissivity greatly enhanced the radiation cooling on the outer surface, while the effect on the fin channels was limited, especially for high and dense fins. It guided the use of the high emissivity coating for reducing the coating cost. The effects of high emissivity coating were further simulated under the vacuum, natural and forced convection. The results showed that at the heating power of 20 W, compared with the radiator coated (ε = 0.93) and uncoated (ε = 0.20), the heat transfer coefficient increased by 95.5%, and the thermal resistance decreased by 39.5% in the vacuum. As for natural convection, the radiation power with coating occupied 39.6% of the total dissipated power and the coating increased the heat transfer coefficient by 26.6% at the heating power of 10 W. Under forced convection, the radiation fraction with coating decreased from 22.6% to 6.4% with the wind speed increased from 0.5 m/s to 4 m/s. In conclusion, for the vacuum, natural convection and low wind speed condition, the high emissivity coating presents a good application prospect in enhancing radiation cooling.