Week 6 - CHT Analysis on a Graphics card

Objectives:

- To perform a steady-state conjugate heat transfer analysis on a model of a graphics card using appropriate materials for the

simulation and properly define the correct solid and fluid zones.

- To run the simulation for best possible mesh with combination of coarse and refined mesh in different regions and explain the reason for choosing the particular mesh settings.

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.

Setup:

Share topology is enabled. Shared topology is the only way to achieve a conformal mesh where bodies meet, and is the only way to be certain that the intersection of bodies is meshed perfectly.

Mesh Type: Tetrahedral

Here the processor or chip is considered to be the source of heat generation.

The volume of model processor is 64mm^3. Chips generate from a few watts of heat to nearly 100 watts, depending on the device and application, referring specifications of various processors.

Most of the processor has the capacity to withstand temperature of 40C - 95C.

Source Term value of processor = 2e7 W/mm^3

Case 1A: Simulation at Inlet Velocity 1 m/s with finer size mesh 5mm.

Global Contour Maps

Local Contour Maps

Case 1B: Simulation at Inlet Velocity 1 m/s with finer size mesh 1.5mm and body sizing applied to fins, base with a size of 1mm.

Global Contour Maps

Local Contour Maps

Case 2: Simulation at Inlet Velocity 3 m/s with finer size mesh 1.5 mm.

Global Contour maps:

Local Contour Maps

Velocity Contour Maps

Case 3: Simulation at Inlet Velocity 5 m/s with finer mesh size 1.5 mm

Global Contours Maps

Local Contours Maps

Velocity Contour Maps

Final Reports:

Ansys 2021 Student Version doesn’t have the option of plotting heat transfer co-efficient. But, we can approximate it by dividing the (net heat flux)/(temperature) i.e 1028.5 W^m^-2K^-1. From above local temperature plots of processor and PCB in all cases, it can be observed that upper surface of PCB, lower surface of heat sink (where the processor is contact to both heat sink and PCB) and contact surfaces of processor are the potential hotspots on the graphic card model.