9.0 New Features

New Coupled-Field Material Property allows Analysis of Peltier Cooling

Workshop 6

Thermoelectric Cooler

9.0 New Features

Workshop

ANSYS v9.0

October 1, 2004Inventory #002157

WS6-2© 2004 ANSYS, Inc.

Parametric Analysis of a Thermoelectric Cooler

Thermoelectric cooling utilizes the Peltier effect. The Peltier effect is seen in conductors as a thermal flux in the direction of an applied current. It is used in many devices, including computers to provide spot cooling or cooling applications where only a low DC voltage such as a car battery is available. An inverse effect also exists in which electricity is generated by a thermal gradient.

Spot Cooling

Thermoelectric Cooler ($69.99 at your local Target)

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Workshop

ANSYS v9.0

October 1, 2004Inventory #002157

WS6-3© 2004 ANSYS, Inc.

The coupling between current density and thermal flux is represented by the Seebeck coefficient. Certain semiconductors have the desirable qualities of a high positive (p type) or negative (n type) Seebeck coefficient, a high electrical conductivity and a low thermal conductivity.

This image shows a Peltier Cooler which has been cut in half.

Conductors (Cu)

Ceramic Mounting Plates (Al2O3)

Peltier Materials (Bi2Te3 n and p)

Parametric Analysis of a Thermoelectric Cooler

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Workshop

ANSYS v9.0

October 1, 2004Inventory #002157

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The device shown at right will be analyzed in this workshop. The top and bottom conductors produce a series connection through the Peltier blocks which is up through the n-type and down through the p-type.

Current Path

Parametric Analysis of a Thermoelectric Cooler

9.0 New Features

Workshop

ANSYS v9.0

October 1, 2004Inventory #002157

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Problem Description:

A thermoelectric cooler is analyzed to determine the “cold side” temperature based on a convection to 23 degrees C. with a film coefficient of 10. The “hot side” is held at 27 degrees C. A 20 Amp current is run through the Peltier material to carry heat away from the cold side to the heat sink on the hot side. Parameters are defined to allow variation of the height of the Peltier material and the current.

“Cold side” Convection surface

Hc = 10 W/(M^2-Deg C) Tb=23 deg C

“Hot side” temperature

sink (27 deg C) 20 Amps

0 Volts

Boundary Conditions

Parametric Analysis of a Thermoelectric Cooler

9.0 New Features

Workshop

ANSYS v9.0

October 1, 2004Inventory #002157

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Workshop instructions:

Step 1. Place the four database files into a working directory. Don’t change the names of the files.

cooler_start.wbdb ! Workbench project db

cooler_start.agdb ! Design Modeler database

cooler_start.dsdb ! Simulation database-

cooler_start.eddb ! Material database

Step 2. Browse to find the project database cooler_start.wbdb and open it.

Parametric Analysis of a Thermoelectric Cooler

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Workshop instructions cont’d:

Step 3. Highlight the DM name to see that Parameters and Named Selections have been checked and that the name filters have been cleared.

Step 4. Double click on the DM name to open the geometry database in Design Modeler.

Parametric Analysis of a Thermoelectric Cooler

9.0 New Features

Workshop

ANSYS v9.0

October 1, 2004Inventory #002157

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Workshop instructions cont’d:

Step 5. Pick Parameters to see the model parameter definitions. The geometric parameter that will be used in the workshop is Peltier_Height.

Step 6. Change the value of Peltier_Height to 0.75 and pick Generate to regenerate the model.

Step 7. Return to the project page and double click on the Simulation name.

Peltier_Height = 0.75

1

2

3

Parametric Analysis of a Thermoelectric Cooler

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Workshop instructions cont’d:

Step 8. Highlight Geometry in the tree and then update the geometry using the 2nd option, “Update: Use Geometry Parameter Values”

Step 9. Review the Named Selections created in Design Modeler. The named bodies, BottomConductors, Ceramic, TopConductors, ntypePeltier and ptypePeltier are used for material assignment. The named faces, ColdSide, HotSide, Terminal1 and Terminal2 are used to apply boundary conditions.

Step 10. Suppress the TopConductors bodies and then invert the suppressed bodies to see only the top conductors. Then unsuppress all bodies.

Named Selections, created in DesignModeler

Parametric Analysis of a Thermoelectric Cooler

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October 1, 2004Inventory #002157

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Workshop instructions cont’d:

Step 11. Pick the icon marked “Data” to open the engineering data menu. Thermal and electrical properties have been defined. The Seebeck coefficient for the Peltier material is defined by inserting Commands for each Peltier part.

NOTE! It is necessary to have the active unit system be metric (m, kg, N, degC, s, V, A) to obtain correct results from this workshop.

Parametric Analysis of a Thermoelectric Cooler

Check active units!

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Workshop

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October 1, 2004Inventory #002157

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Workshop instructions cont’d:

Note: The ceramic material can be shown partially translucent by highlighting the parts and specifying 0.65 in the Graphics Properties Menu.

Parametric Analysis of a Thermoelectric Cooler

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Workshop

ANSYS v9.0

October 1, 2004Inventory #002157

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Workshop instructions cont’d:

Step 12. With the Environment branch highlighted insert a “Given Temperature” boundary condition. You can use the named selection “HotSide” to identify the face.

Step 13. Specify a value of 27 deg C in the details menu for the “Given Temperature.”

Parametric Analysis of a Thermoelectric Cooler

9.0 New Features

Workshop

ANSYS v9.0

October 1, 2004Inventory #002157

WS6-13© 2004 ANSYS, Inc.

Workshop instructions cont’d:

Step 14. With the Environment branch highlighted insert a convection boundary condition on the top surface. You can use the named selection “ColdSide” to identify the face. Specify a film coefficient of 10 and a bulk temperature of 23.

Parametric Analysis of a Thermoelectric Cooler

9.0 New Features

Workshop

ANSYS v9.0

October 1, 2004Inventory #002157

WS6-14© 2004 ANSYS, Inc.

Workshop instructions cont’d:

Step 15. Confirm that ANSYS solution files will saved to the Project Directory using the menu accessed by Tools > Options> Solution:

Step 16. Confirm that special variables are set to turn off error calculation and to request all material properties defined in simulation will be sent to ANSYS. (Tools > Variable Manager)

Parametric Analysis of a Thermoelectric Cooler

9.0 New Features

Workshop

ANSYS v9.0

October 1, 2004Inventory #002157

WS6-15© 2004 ANSYS, Inc.

Workshop instructions cont’d:

Step 17. Review Environment Commands object. Commands are used to convert from thermal to coupled field elements and to apply voltage boundary conditions. Note that the operating current has been parameterized using arg1 in the details.

Step 18. With the Solution branch highlighted, insert Temperature as a result quantity.

Step 19. Right Click on Solution and pick Solve

Step 20. Follow the solution progress by inserting a “Solution Information” object in Solution. This can be inserted into the Solution branch after the solution has begun.

Parametric Analysis of a Thermoelectric Cooler

9.0 New Features

Workshop

ANSYS v9.0

October 1, 2004Inventory #002157

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Workshop instructions cont’d:

Step 21. Determine the temperature of just the “hot side” surface by inserting a second Temperature result and selecting the hot side face in the details window. Solve for this new result (this will be very quick.)

Step 22. The 0.75 mm height does not result in cooling of the hot side. Re-run the solution with a height of 0.5 mm to obtain the solution at lower right. (Changing the height is done by highlighting Geometry, changing the parameter value in the details window and then updating the geometry to the simulation parameters.)

Parametric Analysis of a Thermoelectric Cooler

9.0 New Features

Workshop

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October 1, 2004Inventory #002157

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Step 23. Insert a new result quantity called Cool Surface Temperature and make its minimum value a parameter as shown below.

Parametric Analysis of a Thermoelectric Cooler

P

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Workshop

ANSYS v9.0

October 1, 2004Inventory #002157

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Step 24. Open a new Design Explorer study and create a response surface and sensitivity chart for the Cool Surface Temperature based on a variation of the Input parameters Peltier_Height from 0.2 to 0.3 mm and ARG1 (Current) from 15 to 25 amps.

Parametric Analysis of a Thermoelectric Cooler