Thermal Analysis Of Heat Sinks With Different Fin Configurations

Abstract

A system consisting of IC chips, PCB, grille, heat sink and fan is considered for modeling. The fan is used for forced convection cooling of power dissipating devices. The main role of heat sink is to disperse heat away from high temperature zones. In general, the more surface area a heat sink has, the better it works. The concept of a pin fin is to try to pack as much surface area into given volume as possible. The fins in a heat sink can be cylindrical, elliptical, rectangular or square. This study considers a few of them. Simulations are carried out for heat sinks with different fins configurations and comparative study is done.

Introduction

Heat sinks are devices responsible for dissipating heat away from mechanical or electrical systems to a fluid medium. Heat sinks are categorized into active, passive and hybrid heat sinks. While passive heat sinks rely on natural convection, active heat sinks use forced air generated by blowers or fans for cooling the system. The study involves comparing fin configurations which include rectangular interrupted fins, inline circular pin fins and staggered circular pin fins

Model Setup : Geometry

As shown below in Fig. 1, the system consists of PCB which is exposed to outside known environment of heat flux 20 W/m2. 8 IC chips are placed on the PCB which dissipate power of 10W each. A fan is placed on one end which provides forced convection for cooling of the IC chips. The fan has volumetric flow rate of 20 cfm. A perforated thin vent type grille is used at the other end of the system from where air is flowing out. A heat sink is placed on all the IC chips, which is responsible for cooling of the chips. Fig. 2 shows different pin fin configurations used for modeling.

Fig. 1 Geometry of the system

Fig. 2 Types of pin fin configurations

Model Setup : Mesh

The surface meshing can be seen as in Fig. 3. Simple mesh is adopted for this model as the geometry is not very complex. Fig. 4 shows Y-cut planes of mesh for pin fins.

Fig. 3 Surface Mesh

Fig. 4 Y-cut plane showing mesh on square and rectangular pin fins

Results

Temperature contours on IC chips in Fig. 5 show maximum temperature achieved by chips in each fin configuration.

Fig. 5 Temperature contours on IC chips for different pin fin configurations

**Table. 1** Temperature values for types of heat sinks
Types of Heat Sink	\(Tmax(^oC)\)
Rectangular	58.7209
Staggered Circular	53.2451
Inline Circular	53.1696
Square	52.2451

Conclusion

Thermal analysis is carried out for different pin fin configurations in a heat sink.
From the results, maximum temperature of \(58.72^o\)C on IC chips during rectangular interrupted fin configuration suggests it is not the best one to use for the system.
Not much difference is observed in temperature for inline and staggered circular pin fin configurations.
The lowest temperature of \(52.24^o\)C is achieved during square pin fin configuration. This shows optimum cooling is achieved when heat sink with square pin fins is used for the given system.