Numerical Simulation On Parameterized Model And Output Performance Of Therm-oelectric Device

As a solid-state energy conversion technology,thermoelectric generator can directly convert heat into electricity due to the Seebeck effect.Such devices can effectively utilize the geothermal energy and solar energy in nature,especially for recovering significant amounts of low temperature exhaust heat.As a result,it plays a significant role in improving energy efficiency,upgrading energy mix and protecting the environment.In the present thesis,a commercial thermoelectric generator which consists of 127 thermocouples was analyzed through a three-dimensional numerical model,and relevant experiments were designed to validate this model.Based on the developed model,the influences of semiconductor particle height,section length and load resistance on electricity generation performance of the device in different thermal boundary conditions were investigated.And then the theoretical expression of the device output performance about the above three factors is obtained.It is observed that when the temperatures of both the hot and cold side is constant,the output power increases with section length and the conversion efficiency increases monotonously with the semiconductor particle height.While the effect of particle length on the conversion efficiency is not obvious(when the length is reduced by a factor of 1,the efficiency only increased by 14 percent).For convective heat transfer boundary conditions on the hot side,the output power performed opposite trends,and when the length decreases about a half,the conversion efficiency of the device increased by 137%.The influence of Peltier effect on the performances of the device in closed circuit is also investigated by the developed model.Results show that: the heat transfer was greatly enhanced for constant temperature boundary conditions.When the output power of the device is maximum,the heat flux will raise more 30% and the heat conductivity will also increase over 30%.Under boundary condition of the third type,the influence of Peltier effect on the device performance is more remarkable when the internal resistance(aspect ratio)is lower and the thermal condition of the hot side is poor.Therefore,the external heat transfer condition is also an important factor influencing the optimal performance of the device.