Thermal Design, 2nd Edition

2Heat Sinks

A heat sink is a device to effectively absorb or dissipate heat (thermal energy) from the surroundings (air) using extended surfaces such as fins and spines. Heat sinks are used in a wide range of applications where efficient heat dissipation is required; major examples include refrigeration, heat engines, and electronic device cooling. The most common design of a heat sink is a metal device with many cooling fins, which is referred to as a fin array. The heat sink performance is improved by increasing either the thermal conductivity of the fins, the surface area of the fins, or the heat transfer coefficient. The profiles of longitudinal fins include rectangular, triangular, and parabolic fins. The rectangular profile is fundamental and widely used, particularly with multiple‐fin arrays. The optimization of both a single fin and a multiple‐fin array with forced convection and natural convection are herein presented in detail for the rectangular profile. Finally, a radial fin array is discussed with a design example.

2.1 LONGITUDINAL FIN OF RECTANGULAR PROFILE

We consider a rectangular fin, from which the heat is transferred to the ambient surround at T_∞, as shown in Figure 2.1. To analyze its thermal behavior, it is necessary to be more specific about the geometry. We begin with the simplest case of a straight rectangular fin of uniform cross section, as shown in Figure 2.1. The fin is attached to a base at a constant temperature of T_base and extends into a fluid ...