Integrated design and manufacturing of thermoelectric generator for energy harvesting.

摘要

This dissertation addresses the critical issue of energy crisis by proposing thermal energy harvesting through thermoelectric materials and device. Thermoelectric generators are solid state devices that generate electricity under a temperature gradient. By using thermoelectric material, the wasted heat energy could be converted into electricity to increase vehicle fuel efficiency and to power sensors, depends on the quality and quantity of input heat energy. The scientific innovation is based on recent advance on various kinds of thermoelectric material and novel fabrication method to increase energy efficiency of different situations. The proposed thermal energy harvesting methods are realized in three applications in this dissertation.;Majority of the dissertation work is in automobile application. More than two thirds of the energy is wasted as vehicle exhaust and the average exhaust temperatures at highway driving cycle and city driving cycle are around 500~650 degree Celsius and 200~400 degrees Celsius. The proposed integrated design and manufacture of thermoelectric generator using thermal spray take advantages of environmental friendly and low cost magnesium silicide material. Magnesium silicide layers have been successfully synthesized by Atmospheric Plasma Spray and Vacuum Plasma Spray which has been shown to be an effective way to reduce thermal conductivity of material compared with conventional hot press method. The scientific highlights are 1) by comparing different thermal spray method, the VPS is identified to give best result due to limited oxidation and better microstructure; 2) the interface influence on the thermal conductivity, electrical conductivity and Seebeck coefficient has been intensively studied in this dissertation; 3) the prototype of flat geometry thermoelectric generator was fabricated using thermal spray method for the first time to demonstrate the ability of novel fabrication of TEG by thermal spray method.;In thin film thermoelectric application, filled skutterudite as the state of art high temperature thermoelectric material is investigated in this work. Yb filled CoSb3 skutterudite thin film has been synthesized using DC magnetron sputtering method. The results showed 30% of figure of merit is achieved compared to same bulk material.;In nuclear application, the designed energy harvester can still provide self-sustainable power to monitor the critical parameters of the nuclear power plant or fuel cycle facilities when a severe accident or massive loss of grid power happens. The commercial Hi-z TEG is used together with novel heat sink design to provide power for the wireless communication. The nuclear radiation including gamma, neutron and ion radiation effect on thermoelectric material, thermoelectric module and other electronic component has been intensively studied. Results show proper radiation shielding is need for TEG system during nuclear application.