Conjugate Heat transfer anslysis on graphics card

Conjugate Heat Transfer Simulation on Graphics card

Conjugate Heat Transfer is the combination of heat transfer in solids and heat transfer in fluids. In solids, heat transfer takes place through conduction whereas in fluids it takes place through convection. Conjugate heat transfer analysis is set up for the given graphics card.

A conformal mesh is created and the topology is made to be shared between the components in which the heat transfer takes place.

1)A baseline mesh is created with,

16261 nodes

86529 elements

The named selections are created for inlet,outlet and symmetry bondary conditions.The enclosure is defined as the fluid region and the rest is solid part.

The materials are selected for the simulation as described below-

1. Fins-Aluminium
2. Processor-Gold
3. PCB-Wood
4. Fluid-Air

The processor is set for a constant heat flux condition.The heat flux and heat generation rate parameters are set as described in the image.

The fins and the Printed circuit board(PCB/wood)are set for coupled heat condition.

The velocity at air inlet is set to be 0.3m/s,for the material being preset to air.The outlet is set for zero gauge pressure condition.

The temperature of the inlet air is set to be 300K.

The processor temperature is calculated as area-weighted average over the wall/s corresponding to the processor.Similar process is followed to find the outlet air temperature.

And the heat transfer coeffecient could be found by calculating the area-weighted average of wall fluxes over the selected areas as shown.

The simulation is run for 1000 iterations and the following results were obtained for the baseline mesh.

RESIDUALS PLOT

TEMPERATURE CONTOUR

HEAT TRANSFER COEFFECIENT ON FINS

HEAT TRANSFER COEFFECIENT ON PROCESSOR

PROCESSOR SURFACE TEMPERATURE

OUTLET TEMPERATURE

The maximum processor temperature was found = 475K

The outlet temperature plot and the processor surface temperature plots were found to be periodically varying in nature.The solution is converged as the plots are approaching a steady value and the residuals are decreasing continuously.

2) Mesh Refinement

The mesh is refined near the area where there is maximum amount of heat transfer taking place,ie. on the processor and the walls of the fins.

Face sizing method is inserted in the mesh options and the element size is reduced to get the following specimen.

Number of nodes=32875

number of elements=183718

And the following results were obtained using the previous parameters.

RESIDUALS PLOT

TEMPERATURE CONTOUR

HEAT TRANSFER COEFFECIENT ON FINS

PROCESSOR SURFACE TEMPERATURE

HEAT TRANSFER COEFFECIENT ON PROCESSOR

OUTLET AIR TEMPERATURE

The maximum processor temperature after mesh refinement =303K

The temperature plots now do not follow periodic nature and hold their values with increasing iterations.

Fins are the area where maximum amount of heat is transferred to the moving air through convection.

As expected,the end of fins plate farther away from the air inlet is relatively hotter than the rest of the area,and the end of fins plate closer to the inlet is relatively cooler.