Study On Acoustic And Thermal Compatibility Of Automobile Muffler For Thermoelectric Generator

The automobile exhaust thermoelectric generating system(TEG)which based on the thermoelectric effect of semiconductor material,provides a new idea to solve the increasingly serious energy shortage problem.A typical TEG occupies a large space and may influence the original exhaust system,hinder its wide range of applications,the TEG integrated with exhaust system components can solve the problems above.The muffler integrated with TEG are devices that attempt to integrate TEG and the engine exhaust muffler.The design objectives take the acoustic requirements of the muffler and the temperature distribution of the outer wall surface of muffler into account.The influence of the special structure of the "function-driven" muffler(shell cross-sectional shape and spoiler fins)on the acoustic and thermal performance is discussed by numerical simulation and experiment.Thereby improving the structure and performance integration of the muffler with TEG,and provides guidance for the optimal design of such mufflers.Based on plane wave theory,the acoustic characteristics of the basic muffler units of the traditional muffler are analyzed by numerical simulation,which lays the foundation for studying the acoustic performance of the special muffler units for the TEG,and the feasibility of the simulation method is verified.Based on the Fluent fluid analysis software and LMS Virtual.Lab,the flow field and acoustic characteristics of the special muffler units(polygonal cross section shape and fin)for TEG are studied,focusing on the change of the shape of the muffler,the influence of thickness,distance and length on the compatibility of acoustic and heat.Using the value of the integral of the transmission loss curve in the specific frequency segment as the evaluation index,the influence of the change of the geometric parameters of the special unit is quantitatively evaluated.The results show that the influence of the shape of the muffler on the acoustic compatibility of the muffler is limited,and the fins on the inner wall are obviously improved in the temperature distribution of the muffler,but the acoustic characteristics of the muffler are reduced.The thinner the thickness,the narrower the distance,the shorter the length of the fins with better heat compatibility.Based on the theory of acoustic and heat compatibility of the basic muffler unit,the muffler made for TEG has been designed,the numerical analysis was used to verify the characteristics of the acoustic and heat flow field.The results of bench test and transmission loss are consistent with the numerical results,which shows that the simulation results are reliable.Based on the analytic hierarchy process(AHP)and the importance mark of evaluation indexes from the industry experts,the weights of the evaluation indexes of the automobile muffler for the TEG are analyzed.It is considered that the average temperature of the muffler surface required by the TEG has a particularly important position,as well as the evaluation transmission loss in the specific frequency band.This evaluation accords with current research status of the TEG integrated with muffler.This evaluation index can quantitatively contrast the comprehensive performance of the muffler with different structures.