Variable Properties Model Considering Heat Resistance And Multiphysics Finite Element Simulation Of Thermoelectric Generators

Thermoelectric generator,also called TEG,is a kind of thermoelectric device which can directly convert heat energy into electric energy.It has many advantages as a kind of way to obtain the electric energy from the nature.Although it has been used in some fields,the design process is relatively complicated due to the various parameters and ambiguous objects,many companies are unable to reach an agreement.Based on thermoelectric theory,a variable properties numerical model of TEG unit has been proposed in this thesis.In the model,the thermal resistance of ceramic substrate is included,and a good iterative solution is given for the solution of temperature distribution.The temperature distribution along the thickness of the whole thermoelectric chip is obtained,and the results show that the existence of the thermal resistance will lead to a loss of about 10% of total temperature difference;The temperature distribution along the thickness is near linear under small temperature difference,however,it would deviate from the linear distribution when the temperature difference is large.So the simple constant physical properties model will lead to larger error.Furthermore,we simulated the thermoelectric effect of the TEG unit via COMSOL finite element software,proving the feasibility of the variable properties numerical model by comparison of the temperature distribution.After that,we built an experimental platform for a TEG system based on fluid heat transfer,and measured its temperature distribution and electrical performance.Furthermore,a TEG system model was established in COMSOL finite element software,including a thermoelectric chip with 127 pairs of PN arms and heat exchangers.The temperature distribution and electrical performance of the system was simulated via a coupling of temperature field,electric field and flow field.The electrical performance of the system is simulated under different temperature conditions,which is close to the experimental results.We also investigated the effect of fluid velocity on the temperature distribution through simulation,and explored the range of the optimized velocity.