Passive and Active Electronics Cooling

There are two types of convective heat transfer:

  • Passive Cooling (Natural Convection): When the fluid motion is caused by buoyancy forces that result from the density variations due to variations of temperature in the fluid. For example, in the absence of an external source, when the mass of the fluid is in contact with a hot surface, its molecules separate and scatter, causing the mass of fluid to become less dense. When this happens, the fluid is displaced vertically or horizontally while the cooler fluid gets denser and sinks. Thus, the hotter volume transfers heat towards the cooler volume of that fluid.
  • Active Cooling (Forced Convection): When the fluid is forced to flow over the surface by an external source, such as fans and pumps, creating an artificially induced convection current.