Characterization and application of a thermoelectric generator

• Autor(a) principal: Rocha, Carlos Miguel Oliveira
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/19111
• topic: Eficiência energética; Materiais termoeléctricos

This work is dedicated to the characterization of thermoelectric materials, as well as the simulation of their application and optimization by using a mathematical model. Thermoelectric generators are commonly used in space exploration for many decades, however their application can be extended to the recovery of exhaust gases in automobiles and industrial processes as well as the powering of different types of remote sensors. In this work, the BaGd2NiO5 material and its doping states with Ca were studied for the first time in terms of their thermoelectric properties such as Seebeck coefficient, thermal conductivity and electrical conductivity. A mathematical model was also developed to simulate the application performance of any thermoelectric material for various working conditions. After the experimental validation of the model it was used to simulate the performance of Ca0.15BaGd1.85NiO5 compound, which presented the best thermoelectric properties. The numerical simulations showed that the performance of a thermoelectric generator with this material would be as better as larger is the temperature difference that the module is subjected and as greater is the heat transfer from hot and cold sources to the thermoelectric generator. The electrical conductivity of Ca0.15BaGd1.85NiO5 is the main reason for its low viability since the conversion efficiency was much lower than 1% and the power output was also reduced. This work revealed that the doping of BaGd2NiO5 with Ca can improve its thermoelectric properties, such as the increasing of the electrical conductivity and the reduction of the thermal conductivity. Moreover, the optimization of the application showed to be important in terms of increasing the performance and reducing the material. The mathematical model permitted to conclude that the optimum thickness of the thermoelements will be as smaller as larger is the heat transfer coefficient by convection of the hot and cold fluids. The simulations with the mathematical were also useful to conclude that a generator with thermoelectric properties of Ca0.15BaGd1.85NiO5 could have a wide applicability if its electrical conductivity could be a hundred times greater than the current value.