Estimating case temperature of a component in a plate‐fin heat sink for natural convection heat transfer in an enclosure
1.introduction
Natural convection heat transfer is most often used in many electronic devices as the way of thermal management solution due toits high reliability and low‐cost. But compared with forced convection, the air motion of natural convection is much weaker, which will amount to low heat transfer coefficient, and so heat sink is usually used in natural convection application to expand surface areas for heat dissipation. This article explains how to predict the case temperature of key components encapsulated in enclosure under natural convectionapplication when plate‐fin array heat sink is used.
Most fluids, including air, expand when their temperature rise. This expansion itself reduces the density of local fluid and increases its buoyancy, which will force the fluid to go up. When a powered component transfers heat to its adjacent air, it causes a similar air movement. The movement of heated air induces the cooler air towards the hot component and the cool air is heated by the component and ries once again and this process repeats which makes the hot component reach a thermal tradeoff. Figure 1 shows the effect of natural convection in plate‐fin heat sink. We can see the heated air rises among the internal fins while cool air is drawn into the base of heat sink from its sides. Because natural convection is closely related to the force of gravity, the orientation of heat sink is very important. And this article will focus on the discussion of being oriented horizontally heat sink.
