Conjugate Heat Transfer Analysis on a graphics card.

Description of a conjugate heat transfer analysis:-

Conjugate heat transfer represents the combination of heat transfer in liquids and solids simulteneously. The mode of heat transfer in solids is conduction and convective mode of heat transfer is found predominately in case of liquids.

Theoritically heat transfer in Solids is calculated by using fourier\'s law which involves heat transfer only by means of conduction.

In case of liquids the heat transfer rate is hard to determined because, heat is transported along with the flow of the liquid, in some cases the conductive mode of heat transfer dominates the convective mode.

In viscous models, the viscous effects contributing to heat generation.

In compressible flow, heat generation is fluctuating due to the sight variations in thermal properties of the fluid.

Geometric model used in simulation:-

The geometric model consists of a:-

• Base (With few electronic components)
• Processor (Heat source)
• Fin (To dissipate the heat)

Geometry:-

Enclosure:-

The boundary conditions and materials choosen:-

Velocity inlet: 1 m/s

Free stream temperature: 300k

Heat source: 2e7 W/m^3

Cell zone conditions:-

Fin domain:- Aluminium

Processor domain:- Aluminium

Board domain:-Silicon (created)

Flow domain:- air

Case-1:-Baseline mesh analysis:-

The model and the Enclouser is base meshed as to Obtain the basic profiles of temperature and HTC. With this idea the model can be Further Meshed to the maximum limit of the solver.

Element=5mm.

Mesh:-

Mesh Quality:-

Scaled residuals:-

Temperature contours at Fins:-

Temperature contours at base:-

Temperature contours shows that for given heat generation source, the maximum temperature attained by the processor is 110.69 C

Wall heat transfer coefficient at fins:-

Wall heat transfer coefficient at base:-

Velocity contours:-

Base mesh with smaller element size:-

Element=2mm.

Mesh:-

Mesh Quality:-

Scaled residuals:-

Temperature contours at Fins:-

Temperature contours at base:-

Temperature contours shows that for the given heat generation source, the maximum temperature attained by the processor is 99.38 C

Wall heat transfer coefficient at fins:-

Wall heat transfer coefficient at base:-

Velocity contours:-

Analysis of Refined mesh model:-

The mesh model is further meshed fine by adding the body sizing and refinement at surfaces where the mesh quality was very poor in the base mesh model.

Mesh:-

Mesh Quality:-

Scaled residuals:-

Temperature contours at Fins:-

Temperature contours at base:-

The temperature contours shows the maximum temperature attained by the processor is 360.08C.

Wall heat transfer coefficient at fins:-

Wall heat transfer coefficient at base:-

Velocity contours:-

The variation of temperature contours can be visualized from the velocity contour plooted on a plane along the direction of flow.

The velocity contours plots suggests that the places where recirculation is seen, seems to have higher value of temperataure since the effect of convection is not predominant.

This the reason why the temperature at the right side of the fin is higher than the left side of the fin.