High performance natural convection heat sinks can be designed to include heat pipes. Because natural convection heatsinks often require a large footprint, effective heat spreading is important. Natural convection heat sinks also typically have a large temperature increase over the ambient air. Natural convection heatsinks dissipate anywhere from four to ten times less heat than a forced convection heatsinks with the same surface area.
Additional factors to consider in natural convection heat sink design. Natural convection occurs when there is no externally induced flow and heat transfer relies solely on the free buoyant flow of air surrounding the convection heat sink. Forced convection occurs when the flow of air is induced by mechanical means, usually a fan or blower. Also, the effect of radiation heat transfer is very important in natural convection heatsinks, as it can be responsible of up to 25% of the total heat dissipation. A natural convection heat sink should be positioned so that:
The natural convection extruded heat sink design is based on those previous assumptions. Irwin Indutries offers an extensive line of natural convection and forced convection custom bonded fin heat sinks. In many instances thermal enhancement techniques, such as natural convection heat sinks, must be used to increase the effective surface area or heat transfer and lower the thermal resistance between source and sink. The irregular surfaces of natural convection heat sinks present a formidable challenge for designers in determining the boundary conditions along the fluid-solid interface. Most air cooled natural convection heat sinks are limited, and the overall thermal performance of an air cooled natural convection heat sink can often be improved significantly if more surface area can be exposed to the air stream. Such high performance natural convection heatsinks utilise thermally conductive aluminium-filled epoxy to bond planar fins onto a grooved extrusion base plate. They provide thermal performance specifications for both natural convection and forced convection heat sinks using blowers. Additional factors to consider in natural convection heat sink design. We can determine the thermal performance limits of natural convection heat sinks. The natural convection with heat sink cooling system is the second most desirable option based on reliability, cost and noise. When testing natural convection the other groups tested input chip powers ranging from one to two Watts without a natural convection heat sink, and between one to three Watts with heat sinks.
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