Week 1

Objective

• Get the basic idea of the heat sinks.
• Different types of heat sinks.
• Factors affecting the design and performance of heat sinks.

Heat Sink

In electronic systems, a heat sink is a passive heat exchanger component that cools a device by dissipating heat into the surrounding air. In computers, heat sinks are used to cool Central Processing Units(CPU's) or Processors. Heat sinks are used with high-power semiconductor devices such as power transistors and opto electronic devices such as lasers and light emitting diodes (LED's).

A heat sink is designed to increase the surface area in contact with the cooling medium surrounding it, such as the air. Approach air velocity, choice of material, fin (or other protrusion) design and surface treatment are some of the factors which affect the thermal performance of a heat sink.

Different Types of Heat Sink

The pin fin heat sinks are considered to be amongst the most powerful heat sink design available today. 

The five types of heat sink we have used in the current project:

  1. Pin fin(Cylindrical Fins)

The typical conclusions that can be derived when we use cylindrical pin fin type of heat sink are:

• Heat transfer from and pressure drop across the heat sink increases with the increase in approach velocity, pin diameter, and number of pins. Heat transfer also increases with the thermal conductivity of the material and with the pin height.
• In-line arrangement gives higher heat sink resistance and lower pressure drop than the staggered arrangement.
• Heat transfer models for in-line and staggered arrangements are suitable in designing pin-fin heat sinks.

A typical cylindrical fin type heat sink is shown below:

  2. Pin fin(Cone type fins)

A typical cone type fins heat sink is shown below:

  3. Extruded Fins

  4. Cross Cut Extrusion

  5. Bonded fins

Factors affecting the design and performance of Heat Sinks

1. Thermal Resistance.
2. Material.
3. Fin efficiency.
4. Fin arrangements.