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Thermoelectric Elements

TE Element Joining (LeTourneau University)
“Advancing thermoelectric power generation using advanced joining engineering.”

Welcome to the LeTourneau University TE Element Joining Team's web page. This web page will provide a brief overview of thermo-electric elements, the problems faced in industry, and how our team plans to solve those problems.

Overview

It is estimated that 60-65% of the energy produced in the US is lost to waste heat. Thermo-electrics (TE) provide a means for reclaiming this energy. However, the current joining method for which these elements are assembled is solder, which melts at a temperature of 220°C. The TE Element Joining Team at LeTourneau University is focused on implementing new joining methods for fabricating TE modules. These methods will increase the maximum operating temperature of TE devices, allowing for greater electrical power generation from waste heat. Raising the operating temperature to 1000°C greatly increases the range of applications for these modules.

Thermoelectricity

Thermoelectric couples: Consist of positive and negative elements connected electrically in series and parallel in heat flow. Peltier Effect Image
Peltier Effect: When a current is passed through a couple, a temperature differential is created between the two sides of the thermocouple. This can be used for refrigeration or heating.
Seebeck Effect: If a temperature differential is applied to a couple and a load is applied, power is generated.
Seebeck Effect Image Thomson Effect: The Thomson effect describes the heating or cooling of a current carrying conductor with a temperature gradient.
Figure of Merit (zT):
Describes the effectiveness of the module.

 Figure of Merit Equation

 

 

 

Joining Methods

Laser Beam Welding (LBW)

For welding TE elements to TE elements, Pulsed-LBW was chosen because of its high energy density. The weld will have full penetration on the coatings, have a minimal effect on the element's material properties, and minimize the thermal stress between the coating and the element.

Microwave Welding (MW)

Microwave Welding (MW) is being developed because of its ability to heat the joint interface without excess heating of the entire module. High frequency and dielectric heating are used to heat the interface only, minimizing thermal stresses and diffusion into the elements.

Ultrasonic Welding (USW)

For welding TE elements to copper pads, Ultrasonic Welding (USW) provides a solid state joint that eliminates the need for solder or braze, raises the operating temperature, and minimizes diffusion into the elements.

FEA Modeling

Using COMSOL modeling system in order to aid in the development of hypothesis, as well as parameters to be used.

Evaluation and Validation FEA

  • Mechanical, electrical, and material properties
  • Eddy current
  • Optical/SEM Microscopy
  • Shear Testing
  • Resistivity Testing

 

 

 

 


The Team:

From left to right (Back Row): Zach Jones, Jake Saunders, Kevin Roadcap, Paul Gohdes

(Front Row): Marty Hutton, Brian Ho, Ben Sokolove


For comments, questions or concerns, please contact: BenSokolove@letu.edu

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