Conjugate Heat Transfer Analysis on a graphics card.

Aim:

• To perform a steady state conjugate heat transfer analysis on a model of Graphic card and to find the maximum heat transfer coeffecient and maximum temperature attained.
• To vary the inlet velocity, and to measure the maximum temperture and Heat Transfer Coeffecient

Procedure

Spaceclaim:

• The CAD model of the graphic card is first imported into the space claim environment
• The given CAD model is layered and an enclosure is provided.
• It is made sure that , the topology is shared between the various parts

Meshing:

• The geometry from the space claim is then imported into the meshing interface.
• First a base level mesh is created.
• The base level mesh is checked for conformance.
• Further refininf is done based on the required mesh size.
• The enclosure is given a body sizing with element size 3mm. A mildy coarse mesh is used for enclosure inorder to keep the maximum cell count within range.
• The processor is given a body sizing with element size 0.5mm .A fine mesh is use because the source of heat is from the processor.
• The Fins are given a body sizing of 0.8mm. This is mainly beacause, the fins are the heat transfer element, which transfers heat from the processor to the surrounding.
• The base is given a element size of 3mm. This is given as a coarse mesh, the material to be use has a low HTC

Fluent:

• The mesh is then imported into fluent.
• The viscous model used in k-Epsilon model with realizable wall function.
• The energy is turned on, since this is a comjugate heat analysis problem
• The materials used for different components are as follows

Material	Component	Density `((kg)/m^3)`	Cp `(J/(kg.K))`	Thermal Conductivity `(w/(m.K))`
Gold	Processor	19320	129.8	297.73
ABS	Base Plate	1050	1390	0.25
Copper	Fins	8978	381	387.6

• The Heat source was given under the processor cell zone, considering the volume of the GPU being very small 64 mm^3, we take the power consumption of the GPU to be 5W. So Heat generated = 781250000 `W/m^3`

Case 1 :

The inlet velocity is considered to be 5m/s

Temperature Contour of PCB at 5m/s

Temperature Contour of Fins at 5m/s

Velocity Contour for 5 m/s

Wall heat Transfer Coeffecient

Temperature plot to find that , the solution is converged.

Case 2 :

The inlet velocity is considered to be 1m/s

Temperature contour for PCB at 1m/s

Temperature contour for Fins at 1m/s

Velocity Contour

Wall heat transfer coeffecient

Temperature plot to find that , the solution is converged.

Result :

From the simulation, we can see that, the heat transfer coeffecient is high when inlet velocity is 5 m/s. This enables higher heat transfer. Hence, the maximum temperature is low at 5 m/s when compared with 1 m/s

This is becasue as the velocity increases, the flow converts from a laminar flow to turbulent flow. At higher velocity, the mixing takes place more effectively, thereby increasing the heat transfer coeffecient.

Inlet Velocity (m/s)	Heat Transfer Coeff`(W/(m^2K)`	Maximum Temperature(°C)
5	1108	348
1	544	424