Week 6 - CHT Analysis on a Graphics card

AIM: To Perform a steady-state conjugate heat transfer analysis on a model of a graphics card by using appropriate materials of the simulation.

PROCEDURE:

Spaceclaim Geometry:

• Open the Spaceclaim tool and import the given downloaded Graphics card model.
  
  Graphics card Geomentry:
  
  

Fins Base:

Processor:

Base:

• And set the topological setup to share between the different components of the model.

• CASE 1:

  Then mesh the Baseline model with default mesh elment size and generate the mesh to the model. And it looks like as below fig. Here the defaults mesh formed 65478 number elements, and 14517 number nodes.

  

  And the mesh Metric Quality of the model is mentioned below which looks less than 10%.

  

  Stimulation setup:

• Solver type: Steady state

• Type: Pressure based
• Turbulence model: k-Omega(SST)
• Materials: Different materials are selected to the different parts respectively as below
  

  Parts	Material
  Enclosure	air
  Fin	Aluminum
  Base	steel
  Processor	Titanium

• Material Properties:
  Air:
  
  Steel:
  
  Aluminium:
  
  Titanium:
  
  
• Boundry conditions:
  inlet:
  Type: Velocity - inlet
  Velocity: 5m/sec
  Temperature: 300k
  Outlet:
  Type: Pressure - outlet
  Pressure: 0 Pa
  Temperature: 300k
  Symmetry: Symmetry
  Wall: Wall
• Cell zones:
  Enclosure:
  
  Fins:
  
  Base:
  
  Processor:
  let us calculate the Heat generatred by the Processure by assuming the input power as (P) 65watts and also volume of the model (V) as 8*8*1 mm^3.
  so Heat Generated = P/V = 1015.62 W/m^3.
  
  
  
• After, setup the input data run the standed stimulation upto 500 interations and the output results are mentioned below.
  Residuals:
  
  Temperature contour:
  
  wall heat-transfer-coefficent
  
• Temperature of processor : 1009.755 K
• wall heat transfer coefficient: 4.2918932 W/(m^2 K)
• temperature of base: 661.44792 k
• wall heat transfer coefficient: 42.957291 W/(m^2 K)
• temperature of fins: 468.43402 k
• wall heat transfer coefficient: 37.315839 W/(m^2 K

• CASE 2: Refined Mesh

  Now, refine the mesh in different regions with a refined elememt size as shown below.

  Enclosure body - 3.3mm
  Fine - 0.3mm
  Base - 0.6mm
  Processor - 0.1mm

  Then, the refined meshed models are generated with 495104 number elements and 164038 number nodes are the meshing results are mentioned below.

  Enclosure:

  

  Fine:

  

  Base:

  

  Processor:

  
  
  

• Boundry conditions 1:
  inlet:
  Type: Velocity - inlet
  Velocity: 1 m/sec
  Temperature: 300k
  Outlet:
  Type: Pressure - outlet
  Pressure: 0 Pa
  Temperature: 300k
  Symmetry: Symmetry
  Wall: Wall
• Residuals:
  
  Temperature contour:
  
  Wall heat transfer coefficient:
  
• Temperature of processor :1732.1331 K
• wall heat transfer coefficient: 5.4615749 W/(m^2 K)
• temperature of base: 495.62191k
• wall heat transfer coefficient: 30.80317 W/(m^2 K)
• temperature of fins: 1032.4743 k
• wall heat transfer coefficient: 37.380825 W/(m^2 K
  velocity contour
  

• Boundry conditions 2:
  inlet:
  Type: Velocity - inlet
  Velocity: 3 m/sec
  Temperature: 300k
  Outlet:
  Type: Pressure - outlet
  Pressure: 0 Pa
  Temperature: 300k
  Symmetry: Symmetry
  Wall: Wall
• Residuals:

Temperature contour:

Wall heat transfer coefficient:

• Temperature of processor : 1451.2472 K
• wall heat transfer coefficient: 5.8151634 W/(m^2 K)
• temperature of base: 474.35361 k
• wall heat transfer coefficient: 34.088707 W/(m^2 K)
• temperature of fins: 729.5296 k
• wall heat transfer coefficient: 40.400327 W/(m^2 K)

velocity contour:

• Boundry conditions 3:
  inlet:
  Type: Velocity - inlet
  Velocity: 5 m/sec
  Temperature: 300k
  Outlet:
  Type: Pressure - outlet
  Pressure: 0 Pa
  Temperature: 300k
  Symmetry: Symmetry
  Wall: Wall
• Residuals:
  
  Temperature contour:
  
  
  Wall heat transfer coefficient:
  
• Temperature of processor :1421.2933K
• wall heat transfer coefficient: 6.4399 W/(m^2 K)
• temperature of base: 471.06993 k
• wall heat transfer coefficient:37.319275 W/(m^2 K)
• temperature of fins: 682.21635 k
• wall heat transfer coefficient: 42.968 W/(m^2 K)
• velocity contour:
  

CONCLUSION:

The model is successfully stimulated by using ANSYS Fluent under Acedemic license limits with differnt input conditions.

The maximum temperature and heat transfer coefficient attained by the processor, Fin, of Baseline and refined models at varies velocities are Base are shown below.

	Baseline at 5 m/sec	Refined model at 1 m/sec	Refined model at 3 m/sec	Refined model at 5 m/secc
maximum Temperature (k)	1009.755	1732.133	1451.2472	1421.293
maximum Heat Transfer Coefficent W/(m^2 K)	42.9572	37.38082	40.4003	42.968

Here, from the Residual ploting results in all cases are results as repetitive plots, we can conclude that the model is convergenced. Here the Processor acts as the power sorce input.

Here, the baseline model is refined with minimum element size that results increase in the number of elements that are generated unnder Acedemic licence limits.

And also we observe that the maximum Temperature is raised at the Processor surface in all different input cases. And based on the assigned materials properties also the stimulation results are generated. And also we observe that the increase in velocity input the temperature raised on the components surface are gradually decresed. So we conclude that the higher velocities acts as a coolent. Here covection is occurs when generated heat is removed by the inlet air flow and Conduction occurs when the generated heat is transferred from the proceeser to the adjacent parts.