Week 6 - CHT Analysis on a Graphics card

GIVEN

Perform a steady-state conjugate heat transfer analysis on a model of a graphics card

Procedure

THE PURPOSE OF CONJUGATE HEAT TRANSFER ANALYSIS IS TO VARIOUS TEMPERATURES CONCERNING SOLIDS AND FLUIDS, DUE TO THERMAL INTERACTION BETWEEN THEM LIKE HEATING WATER IN A PAN OR HEAT TRANSFER FROM THE ENGINE TO THE RADIATOR AND RADIATOR TO ATMOSPHERIC AIR.

STEPS TO BE FOLLOWED

Step 1: Initially, start with importing the geometry to the Ansys workbench

1. Encloser

2. Fins

3. Base

4. Processor

Step 2: From the given geometry create two kinds of mesh (coarse mesh and fine mesh) to perform grid independent study for the fine mesh analysis of their case of velocity 1m/s,3m/s and 5m/s.

1 coarse mesh

2 Fine mesh

The fine mesh has been created concerning the heat transfer that occurs from the processor to the fin and the fin to the fluid(air).

After generating the mesh, the number of nodes and elements is investigated using the statistics option. Then the mesh quality is checked by choosing the mesh matrices option in the quality section.

Step 3:In this step, the meshed geometric file has been imported to the fluent module and set the following conditions as follows in the fluent in solving the problem.

case 1:coarse mesh

This procedure is followed in Ansys fluent

SOLVER TYPE	Pressure based
VELOCITY FORMULATION	Absolute
TIME	Steady
VISCOUS MODEL	K-omega SST model and enable energy equation to solve the energy equation
MATERIAL	Fluid: air Solid: aluminium, silicon, polystyrene
CELL ZONES	Fluid flow region: air fin: Aluminium graphic processor: silicon PCB board: polystyrene
BOUNDARIES (depends on the momentum ratio)	Inlet_x (velocity inlet) Velocity magnitude:1m/s
Report definition	Area weighted average of temperature on the processor Maximum temperature of temperature on the processor HTC on the processor

the hybrid scheme is used for the initialization

Results for coarse mesh

contour plots

streamline plot

case 2:Fine mesh

In fine mesh, I followed a parametric study to analyse three velocities of the flow

This procedure is followed in Ansys fluent

SOLVER TYPE	Pressure based
VELOCITY FORMULATION	Absolute
TIME	Steady
VISCOUS MODEL	K-omega SST model and enable energy equation to solve the energy equation
MATERIAL	Fluid: air Solid: aluminium, silicon, polystyrene
CELL ZONES	Fluid flow region: air fin: Aluminium graphic processor: silicon PCB board: polystyrene
BOUNDARIES (depends on the momentum ratio)	Inlet_x (velocity inlet) Velocity magnitude: parametric input
Report definition	Area weighted average of temperature on the processor Maximum temperature of temperature on the processor HTC on the processor

the hybrid scheme is used for the initialization

Results for coarse mesh

contour plot

streamlines

SOLUTION DISCUSSION

1. compared to the course mesh refined mesh gives the best result comparatively.

2. When we increase the velocity of the flow the mass flow rate of air increases and takes more amount of heat from the fins'

3. The Maximum temperature depends on the velocity of the inlet air. The more the velocity less the temperature of the graphic processor.

4. The potential hotspot for the graphics card is the processor.

Inlet_velocity (m/s)	T_avg (k)	T_max (k)	HTC (W m^-2 K^-1)
1	614.84305	616.30487	-6.4150846
3	447.64305	448.98923	-11.269007
5	407.28722	408.63297	-16.672601