Experimental and Numerical Study of Fin Heat Sinks Systems

A. Husain, T.; A.K Shahad, H.; F. H. Ali, And

	Experimental and Numerical Study of Fin Heat Sinks Systems
Iraqi journal of mechanical and material engineering
Article 1, Volume 9, Issue 3, 2009, Pages 279-295
Authors
T. A. Husain; H. A.K Shahad; and F. H. Ali
Abstract
In this study has been compared the heat transfer performance of various commnoly fin geometries by studying the temprature and velocity distribution. Comparitive thermal tests have been carried out using aluminum heat sinks with extruded fins, staggered square pins, and staggered cylinderical pins in forced convection air flow environments. The extruded fin heat sink was designed to minimize the pressure losses across the heat sink by reducing the vortex effects to enhance the thermal performance by maintaining large exposed surfaces area available for heat transfer. Experimental and theoretical investigation were carried out. The most electronic components operates in the range of temprature between (40)oc and (60)oc therfore in the experimental tests, air velocity was varied from (2) m/s to (6) m/s and the heat flux from (20) Watt to (40) Watt are used to obtain the range of temprature. The temprature of the solid structure was measured experimentally by using (15) thermocouple. They are distributed on the heat sinks uniformly.The velocity and temprature of the flow field in the test section was measured experimentally using portable anemometer. A software packages (ANSYS 5.4) was used to carry out the theoretical study using adiabatic flow condition. This gives a good ability to calculate the velocity and pressure distributon and sketching the eddies wake behind the pins and fins in the core of the heat sink. By the aid of this software package a three-dimemsional model was built by putting horizontal orintation only. The model boundary condition can be easily varied through (ANSYS 5.4), including all ranges used in the present study. The flow was analyzed for three-dimensional steady, adiabatic, incompressible and viscous. Navir-stocks equations and continuity equation were solved. A two-equation K- model (turbulence model) was also solved by this program. The straight fin experienced the lowest amount of flow by-pass over the heat sink. For this particular application, where the heat source is localized at the bottom of the heat sink base plate, the overall thermal resistance of the straight fin was lower than the other two designs mainly due to fins have large area of convection. The relative thermal resistance for cylinderical pin-fin heat sink was higher than the other two designs. This is due to the improve distribution of air flow around the circular pin.The results show that when the heat sinks have the same area of convection, the cylinderical pin-fin heat sink was the best choice while when the heat sinks have the same area of conduction the straight fin was the best choice because it give large exposed surface (large area of convection).

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