Conjugate Heat Transfer Analysis on a graphics card.

Aim: To perform conjugate heat transfer analysis on a graphic card

Objectives:

1. Run the simulation by varying the velocity from 1m/sec to 5m/sec for at least 3 velocities and discuss the results.
2. Find out the maximum temperature and heat transfer coefficient attained by the processor.
3. Prove that the simulation has achieved convergence with appropriate images and plots.
4. Identify potential hotspots on the model.

Geometry:

For thermal analysis of the graphic card, first, we need to create an enclosure and then create a conformal mesh for proper analysis. Also share topology is enabled to perform conjugate heat transfer.

Mesh details:

Initially, an analysis with base mesh was done but it was not giving results. So mesh was refined for proper analysis.

Processor, Baseplate, and Fins are having an element size of 0.5 mm and the enclosure is having a size of 2 mm with max allowable size 4 mm.

No of element - 916866

Setup:

A total of three cases are analyzed in this study.

A steady-state pressure-based solver is used.

THE turbulence K-E model is used for this analysis.

The energy equation is turned on.

Materials: processor- Gold, Baseplate- aluminum, and Fins- copper.

The processor is the heat generator in this case therefore a source term is added to it.

Source term- 156250000 W/m³

Outlet condition is kept as a pressure outlet with 0 gauge pressure.

Inlet condition:

Case 1 velocity v = 1 m/s

Case 2 v = 2.5 m/s

Case 3 v = 5 m/s

Case 1:

Case

Case 2:

Case 3:

Results and discussion:

Case 1 Case 2 Case 3

Max temp: 413.44 K 362.683 K 341.226 K

Velocity: 1 m/s 2.5 m/s 5 m/s

Wall heat transfer coefficient: 1428.01 [W m^-2 K^-1] in all 3 cases

From the following image, we can clearly see that due to heat generation from the processor is making the region a potential hotspot.

The primary region for this hotspot is the improper circulation of air. We can clearly see from the following velocity vectors that behind the fins and after processor, the air circulation is very restricted which causes the heat to accumulate in those regions.

Conclusion:

• The refined mesh is required to perform these types of simulations accurately.
• From all three cases, it is clear that air velocity plays the most important role in reducing the overall temperature of the graphic card.
• Case 1 is having the minimum velocity thus the maximum temperature of 413.944 K is observed in this case.
• Case 3 is having the highest velocity thus it is having the lowest temperature of 341.226 K among all cases.
• Graphics cards can further be cooled if we redesign it in such a way that processor is exposed to maximum airflow.