Thermoelectric System Modeling and Design

Abstract

allowing me to do research at the Advanced Energy Lab, while providing me great insight in to my research. I would like to thank my lab colleagues Joey Richardson, Nick Kempf and Tony Varghese, without whom this work would have been difficult to complete. I would also like to thank my former lab colleague Luke Schoensee for his help in this work. I would also like to thank the committee members Dr. John Gardner and Dr. Inanc Senocak. Finally, I would like to acknowledge my parents Asoka and Bandula, for all their support throughout my life. vi ABSTRACT Thermoelectric generators (TEGs) convert heat to electricity by way of the Seebeck effect. TEGs have no moving parts and are environmentally friendly and can be implemented with systems to recover waste heat. This work examines complete thermoelectric systems, which include the (TEG) and heat exchangers or heat sinks attached to the hot and cold sides of the TEG to maintain the required temperature difference across the TEG. A 1-D steady state model is developed to predict the performance of a TEG given the required temperatures and device dimensions. The model is first validated using a 3-D model and then is used to examine methods to improve the TEG performance. A numerical model is developed to predict the thermal performance of heat exchangers to be used in combination with the TEG model. The combined thermoelectric generatorheat exchanger model, is compared with a 3-D model and then used to predict the performance of a TEGheat exchanger system used to recover waste heat from a diesel engine. Next natural convection heat sinks are modeled and studied to be implemented with the TEG. A model is developed to predict the performance of a system applied for power harvesting in a nuclear power plant. The model is also used to design a system to recover waste heat from the human body. Finally, a novel natural convection heat sink is suggested, where microwires act as the extended surface for the heat sink. The microwire heat sink is modeled accounting for the relevant thermal physics. The microwire heat sink is used in combination with the TEG model to predict the performance of a system used to recover waste body heat. vii TABLE OF CONTENTS