Week 6 - CHT Analysis on a Graphics card

AIM:

• To perform a steady-state conjugate heat transfer analysis on a graphics card model

OBJCETIVES:

• To simulate the velocity by varying the velocity from 1m/sec to 5m/sec and to discuss the results.
• To find out the maximum temperature and heat transfer coefficient attained by the processer.
• To prove the simulation has achieved convergence with appropriate plots and images at various materials.
• To identify potential hotspots on the model.

THEORY:

Conjugate Heat Transfer (CHT) Analysis:

Conjugate Heat Transfer analysis is used for the processes that involve a variety of temperatures concerning solids and fluids, due to thermal interaction between them. A typical example would be the heating or cooling of a solid by the flow of air.

The exchange of heat between two bodies is known as heat transfer and the rate of heat transfer is directly proportional to the temperature difference between them. Heat transfer in solids is usually occurred by conduction whereas in the case of fluids heat transfer occurs by convection. Efficiently combining heat transfers between solids and fluids is the key to designing effective coolers, heaters, or heat exchangers. Forced convection is the most common way to achieve higher heat transfers. For some applications, the performance is further improved by combining convection with phase change(for example liquid water to vapor phase change).

Heat transfers in solids and heat transfers in fluids are usually combined in the majority of the applications. This is because fluid flows around solids or between solid walls and usually solids are immersed in the fluids.

Graphics card:

• The graphics card (video card, display card, display adapter) is an expansion card that generates a feed of output images to a display device (such as a computer monitor ). The integrated graphics processor can perform additional processing, removing this task from the central processor of the computer.

SOLVING & MODELLING APPROACH:

GEOMETRY:

• The model of the specified graphics card is open in SpaceClaim. in the enclosure, which. In order to achieve conformal mesh between various components and allow for information sharing between various mesh zones, share topology between the various components must be enabled.

Base:

Fins:

Processor:

Final Geometry:

Enclosure:

MESHING:

• To make the mesh conformal and to lower interpolation error, the shared topology is developed.
• The baseline mesh was generated to 0.002m and has been imported into the mesh interface.
• The named discussion is made in the graphics card interfaces.

Mesh Metrics:

SETUP:

• Turn on the energy Equation as the temperature is involved in the problem,

Solver: Steady

Type: Pressure Based

Turbulence Model: K-Epsilon (Realisable)

Materials: Different materials are used for each part, Some of which are custom created.

PARTS MATERIAL

Fins - Copper

Processer - Titanium

Base - Steel

Enclosure - Air

(1) Titanium:

(2) Aluminium:

(3) Gold:

Boundaries:

INLET:

Type: Velocity inlet

Velocity: 1m/sec

Temperature: 300k

Outlet:

Type: Pressure outlet

Pressure: 0Pa (gauge pressure)

Method of Initialization: Hybrid.

Cell Zone:

• The processor wall is selected in the zone tab's edit option, the source term is enabled by choosing one source, and the volumetric heat source value of 5e7 w/m3 is entered as a constant. This equates to 150 W, which is sufficient for the majority of graphics cards but necessitates more for cards like the Nvidia RTX, which needs more than 320 W and a system power of 750 W. Since most mid-range cards only require 150 W, these typically have a 6 pin power connector. GPU power connectors are discussed at https://www.gpumag.com/.
• Selecting the processer wall results in the creation of the maximum temperature plot.
• The complete graphics card zones are chosen to generate the temperature contour.

SOLUTION:

CASE-1: BASE MESH:

• Velocity: 1m/s,
• Temperature: 300k

Residual plot:

Velocity Contour:

Overall Static Temperature:

Fin Temperature:

Base Temperature:

CASE-2:REFINED MESH:

• The refined mesh of 0.001m is generated after the geometry has been imported into the meshing interface.
• Inlet velocity: 5m/s
• Inlet temperature: 300k

Mesh Metrics:

Residual Plot:

Velocity Contour:

Temperature Contour:

Overall Static Temperature:

Fins Temperature:

Base Temperature:

Processer Temperature:

CASE-3: BASE MESH:

• Inlet Velocity = 5m/s
• Temperature = 300k

Residual plot:

Velocity contour:

Overall Static Temperature:

Fin Temperature:

Base Temperature:

Processor Temperature:

RESULTS:

CASES VELOCITY TOTAL TEMPERATURE OF TOTAL HEAT TRANSFER COEFF

GRAPHICS CARD (K) ON GRAPHICS CARD (w/m^2k)

Case 1 (Base Mesh) 2 961 1050

Case 2 (Refined Mesh) 5 1067 1050

Case 3 (Base Mesh) 5 1016 1050

CONCLUSION:

• Hence, accurate data on the temperature distribution are obtained as the number of elements increases.
• It is clear from the data above that as inlet velocity rises, graphics card component net temperature decreases.
• It can be inferred the result has been higher inlet velocity results in better cooling and a lower average temperature, safeguarding the components.
• If the velocity is high then they get the result is better cooling and less throttling.
• Further evidence that greater velocity enhances cooling comes from the fact that component temperature increases as inflow velocity falls from 5 m/s to 1 m/s.
• We conclude the observations, we can say the velocity value is high then they get better results in better cooling and lower average temperature thus we can maintain the optimum temperature at the processor to avoid damage to the components.