Research On Semiconductor Thermoelectric Generating System Of Vehicle Exhaust Gases

With the introduction of 100 km fuel consumption public system and people pay more and more attention on the energy conservation and emission reduction of the automotive industry, the fuel economy performance of the engine has become an important index which decides whether people buy a car or not. But it is very difficult for us to promote the fuel economy performance by improving the performance of the engine, so this dissertation changes the way, for the high waste heat characteristic of the engine, making use of the thermoelectric technology to recover the exhaust waste heat, change it into electrical energy, and stored in the battery, which can be used by electrical appliances in the vehicles or be the electric power source of the hybrid vehicles. Which make very important sense for the energy conservation and emission reduction of the automotive industry.Firstly, mathematic model of the working process for the thermoelectric module(TEM) is built by means of thermodynamics theory, and the numerical calculation of the output power and thermoelectric conversion efficiency of the thermoelectric nuicouple dependence on the arm length and aspect ratio is studied in the MATLAB software, and the thermoelectric coupling simulation analysis of the output power and conversion efficiency of the nuicouple, and the corresponding results are compared.Secondly, after taking the non-linearity of the material and contact effect into account, the simulation model of the nuicouple which is closer to the actual working situation is established, and the thermal, electric, structural coupling analysis is done by ANSYS software, the sensitivity of thermoelectric performance caused by contact thermal conductivity is analyzed, and the arm length l, cross-sectional area side length s dependence on the output power, conversion efficiency and thermal stress of the nuicouple is studied. Then a new type of TEM is proposed by optimizing the structural size of the nuicouple, which can get the output power and conversion efficiency close to an optimum value under the situation the nuicouple will not destroyed by the thermal stress.Thirdly, the performance test experimental platform of the TEM is established, and the output power experimental test of the new structural size TEM is done, then the test result and the simulation result are compared, based on this, the simulation model is validated.Lastly, the heat-flux coupling analysises of the different structural scheme thermoelectric generators(TEG) which use the new type of TEM are done by the Fluent software, the highest hot side temperature of TEMs is obtained, and then the fixing location of the TEG is decided in the exhaust system, the output power and thermoelectric conversion efficiency are also obtained, and then the best scheme is selected, which settles the basis of the facture, installation of the thermoelectric generating system.