<p> With increased public interest in protecting the environment, scientists and engineers aim to improve energy conversion efficiency. Thermoelectrics offer many advantages as thermal management technology. When compared to vapor compression refrigeration, above approximately 200 to 600 watts, cost in dollars per watt as well as <i>COP</i> are not advantageous for thermoelectrics. The goal of this work was to determine if optimized pulse supercooling operation could improve cooling capacity or efficiency of a thermoelectric device. The basis of this research is a thermal-electrical analogy based modeling study using SPICE. Two models were developed. The first model, a standalone thermocouple with no attached mass to be cooled. The second, a system that includes a module attached to a heat generating mass. With the thermocouple study, a new approach of generating response surfaces with characteristic parameters was applied. The current pulse height and pulse on-time was identified for maximizing Net Transient Advantage, a newly defined metric. The corresponding pulse height and pulse on-time was utilized for the system model. Along with the traditional steady state starting current of <i>I<sub>max</sub>, I<sub>opt</sub></i> was employed. The pulse shape was an isosceles triangle. For the system model, metrics new to pulse cooling were <i>Q<sub>c</sub></i>, power consumption and COP. The effects of optimized current pulses were studied by changing system variables. Further studies explored time spacing between pulses and temperature distribution in the thermoelement. It was found net <i>Q<sub> c</sub></i> over an entire pulse event can be improved over <i> I<sub>max</sub></i> steady operation but not over steady <i>I<sub> opt</sub></i> operation. <i>Q<sub>c</sub></i> can be improved over <i>I<sub>opt</sub></i> operation but only during the early part of the pulse event. COP is reduced in transient pulse operation due to the different time constants of <i>Q<sub>c</sub></i> and <i> P<sub>in</sub>.</i> In some cases lower performance interface materials allow more <i>Q<sub>c</sub></i> and better <i>COP</i> during transient operation than higher performance interface materials. Important future work might look at developing innovative ways of biasing Joule heat to <i>T<sub>h</sub>.</i></p>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:10004791 |
| Date | 02 February 2016 |
| Creators | Piggott, Alfred J., III |
| Publisher | Michigan Technological University |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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