More sophisticated calculation methods, software or testing can then be used to refine the design. This analysis is for a heat sink whose base is oriented vertically with cooling via natural convection and radiation only as shown if figure 1. Values for L and H are first chosen based on your heat sink design constraints.
The the width, W of the heat sink, spacing between the fins, s and number of fins, N will then be calculated for the selected values of L and H. The convection heat dissipation, Q c1 from area A 1 the external side surfaces of the heat sink shown figure 2 is first calculated.
This is determined using equation 1. The convection coefficient, h 1 for the area A 1 is calculated using equation 3. This formula is for natural convection from a vertical surface. See reference [2] for details regarding the development of this formula.
The area A 1 includes small areas of horizontal surfaces. The difference in magnitude of the natural convection coefficient for horizontal and vertical surfaces is not significant and the horizontal areas are small relative to the vertical surfaces. As such utilization of equation 3 for this entire area will not introduce significant error and will simplify the calculation.
The next step in the calculation is to determine the heat dissipation, Q c2 due to natural convection from surface area, A 2 of the fins as shown in figure 2. The optimum spacing between the fins, s opt that produces the maximum heat transfer due to natural convection is given by equation 5.
The width of the heat sink is then calculated based on the number of fins required to dissipate the heat from the heat sink. Reference the blog post, Sizing heat sinks with a few simple equations for details regarding the calculation methodology. Note: This calculator should not be used in instances where the heat source is much smaller than the base of the heat sink. Concentration of the heat source over an area much smaller than heat sink base is not taken into account in this calculator.
Dimensions L: mm. W: mm. Material Predefined materials:. Thermal conductivity:. Heat Transfer Surfaces Select the surface s from which heat transfer will occur. Quickly determine the best cooling method for your design Analyze natural convection cooled heat sinks in multiple orientations for your application. Include radiation and specify the surface emissivity for further accuracy.
Are you using a fan for high power components? Evaluate the fan cooled heat sink's performance by entering the fan curve data points. Natural convection.
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