Analysis And Optimization On Thermal Stress Of Automobile Waste Heat Thermoelectric Device

The vehicle industry has already developed for a century since the first car of the world has been made, and the new vehicle technology keep developing and promoting in the environmental and economical field. Now, the new technology applying to vehicles must consider the fuel consumption and air pollution. The most important norms in the international automobile market will be the energy saving and environment protecting. Therefore, in the era of the vehicle engine has the best perfonnance in energy saving, studying new board methods to make full use of the burning chemical energy could further improve vehicle energy-saving performance. Thermoelectric generator (TEG) is a new method which could turn west heat into electric power based on the material property. Domestic research on TEG technology just staring while overseas has been studied for years. After a study of the TEG device operation environment and the structure, I have put forward the analysis the thermal stress distribution on the TEG device.This paper mainly studies the thermal stress on the TEG set. The main content is calculating the stress field with the CAE software. The preliminary CAE treatment is handled by hyermesh, a very useful engineering software, extract the middle plane and discrete the model with finite elements, use the cooling water tank and air channel’s wall temperature provide by Fluent computed result as the boundary condition to compute the temperature distribution of the finite element model. Then set the temperature computed result and constraint conduction to the finite element model, analysis the thermal stress distribution by ANSYS. The thermal stress distribution result indicates a few stress concentration areas on the of the air channel, where the constraints have been set, and the X direction stress sharing has a uniform distribution with a smaller value, but the air channel get a bigger sharing. Y direction stress sharing has a smaller stress, obvious stress concentration areas with grate gradient in Z stress sharing. The fixing beams changed the stress distribute of the water tank surface, and several stress concentration points in the bolt position of the beam surface. Many stress concentration points on the boundary of thermoelectric module array.Through rationalization analysis, put forward an optimization objective decreasing the max stress on the air channel surface. In order to achieve the target, limit the nodes’s six degrees of freedom which locate on the middle of air channel. Keep other boundary all the s(?)me as the original model and calculate the thermal stress field. The stress concentration area show up around those limit nodes in the original model all has gone, the max stresses value have been decreased, as well as sharing of Y direction and Z direction. Only X direction sharing have increased a several MPa. In order to eliminating the stress concentration areas on the air channel surface, change the sharp edge to a round transition structure, calculate the thermal stress distribute with the same temperature and constraint condition. Max value of thermal stress and X direction share and Y direction share did not have changed much, but Z direction stress share decreased36.1MPa, therefore the optimization right on their target. In addition, reasonable selection of material also can reduce the thermal stress of the device.Applying the maximum temperature which the device could bearing as boundary condition, and obtain the extreme stress value on steady state. Geometry optimization got remarkable result. Research shows that devices unreasonable installation can bring serious thermal stress concentration problems.