Natural Convection Overview

Natural convection is a mechanism of heat transportation in which the fluid motion is not generated by an external source. Instead the fluid motion is caused by buoyancy, the difference in fluid density between two locations, which is most commonly due to a temperature difference between those two locations. The fluid velocity is very low in natural convection which limits the ability of the heat sink to transfer energy to the environment. To improve the heat sink's ability, the surface area of the heat sink should be as large as permitted by the application. Radiation also plays a major role in the performance of the heat sink and so the heat sink should be treated, either anodized or painted. This surface treatment improves the surface emissivity, or its ability to radiate heat to other objects in the environment. When designing a heat sink for natural convection, the orientation should be vertical and the fins should be widely spaced, about ¼".