Structural Optimization And Experimental Study On Thermoelectric Generator Based On Diesel Engine Simulated Exhaust

Thermoelectric generator(TEG)technology has attracted the research interest of domestic and foreign scholars due to its pollution free,low maintenance cost and other advantages,and it has a wide application prospect in many industries.In this paper,the TEG module was optimized and analyzed by combining experimental test and numerical calculation,the effect of cross sectional area and the hot side temperature of TEG modules were studied.The output performance of single TEG module and two-stage TEG were explored.The heat exchanger was designed and processed;the relative experiment was carried out.The specific contents are as follows:(1)A TEG module with 199 thermoelectric(TE)couples was simulated with constant and variable property parameters respectively by using finite element analysis software.It indicated that the simulative results with variable property parameters were closer to the experimental results.Meanwhile,it was found that the open circuit voltage and output power were proportional to the number of TE couples.The parameterized rectangle-TEG(R-TEG)and circle-TEG(C-TEG)modules with 2 TE couples were established respectively;it was found that the performances of TEG have not relevant to the shape of TE couple.When the hot side temperature was constant,the open circuit voltage and the efficiency increased but the output power decreased with the decrease of cross sectional area;when the cross sectional area was constant,the open circuit voltage,output power and efficiency increased with the increase of the hot side temperature.The intersection of the respective output power and efficiency of R-TEG and C-TEG were regarded as an optimized value.The maximum output power and efficiency of the optimized R-TEG can reach to 91.88 W and 4.5% respectively.(2)The experimental study on the influence of cooling mode on the output performance of TEG module was carried out,and the results showed that water cooling has better cooling effect on TEG module.When the cooling mode was water cooling,the experimental study on the output performance of different types of TEG modules was carried out.The results showed that the internal resistance,open circuit voltage,output power and efficiency of TEG module increased with the increase of temperature difference and the number of TE couples.The experimental study on the output performance of two-stage TEG module was carried out.The results showed that when the hot side temperature was constant,the total open circuit voltage of the two-stage TEG module with the same type of TEG module in series was equal to the open circuit voltage generated by its corresponding single-stage TEG module,the output power generated by two-stage TEG module was lower,and the heat absorbed by two-stage TEG module was far less than that absorbed by single-stage TEG module.Therefore,the efficiency of two-stage TEG module can be improved by 12.3% compared with single-stage TEG module.(3)A three-dimensional model of heat exchanger was established,and the heat exchanger fins with different lengths,heights and spacing were simulated.The results showed that the longer the fin,the smaller the spacing and the stronger the heat transfer ability of the fins.The fin height had an optimal value,which made its performance better.Based on this,a model of a heat exchanger with an inner fin length of 400 mm,a height of 34 mm and a spacing of 19 mm was produced,and the temperature fields of the finned and finless heat exchanger models were measured and simulated separately.The results showed that the maximum deviation between test results and simulation results is 6.7%.The hot air was used to simulate the exhaust of diesel engine and the experiment of thermoelectric generation was carried out.The results showed that heat exchanger with fin had a stronger heat transfer capacity.The higher inlet temperature and the closer TEG module to the entrance,the better the TEG module's output performance.