Research On Recovery Efficiency Of Thermoelectric Dynamic Operation

Automobile industry is one of the mainstay industries in our national economy.With the development of automobile industry,the energy consumed is also increasing.In order to improve the efficiency of energy,thermoelectric generation technology is used to convert the thermal from the waste gas into electric energy.In this paper,the dynamic energy recovery is predicted by the fluid-thermal-electric transient multiphysical field numerical model.On the basis of the traditional thermoelectric generatotr system coupling phase change material(PCM),to study the effect of phase change material on the system output performance.The research contents are as follows:(1)Establish simulation model and experimental device.In this paper,to verify the simulation model,an experiment system was built with variable external resistance load and adjustable temperature at the hot and cold sides.The optimal load resistance of 4Ω and the inlet velocity of 1.3m/s were determined as the boundary conditions for subsequent simulation.The transient model is used to predict the dynamic energy recovery.The more stable the thermal source condition is,the higher the output performance of the system is.(2)To couple energy storage system based on fluid-thermal-electric model.The phase change material was introduced and Design of Experimental(DOE)method was adopted,and the signal-to-noise ratio was introduced as the evaluation index to analyze the thermoelectric performance of the system.The response of four factors was determined as: heat source thermal power > height of the PCM box > filling ratio of the PCM> PCM type.According to the safe operating temperature of the thermoelectric module(TEM),the heat source is divided into two parts: low temperature and high temperature.PCM are used to achieve the purpose of "peak cutting and valley filling" at low temperature,and protect the TEM at high temperature to increase the output performance of the system.(3)Establish thermoelectric system with multiple TEMs.In order to make full use of the energy in the low,middle and high temperature of the exhaust pipe.The flatplate TEG system was taken as the research object in the paper,and the finned structure and phase change materials were studied,respectively.Along the direction of waste gas flow,the temperature decreases continuously,resulting in uneven surface temperature of the TEM,which affects the efficiency of thermoelectric conversion of the system.The addition of metal fins can increase the temperature of the hot side of the TEM,but the TEM near the exhaust inlet appears overheating phenomenon.Placing phase change materials between the TEM and the heat exchanger can prevent TEM from overheating,and improve the temperature uniformity of the hot side of TEM.(4)Based on the TEG system with multiple TEMs,the topological method of multiple TEMs is realized.There is a certain amount of energy loss along the gas pipe,and the output performance of the TEM decreases.In this paper,five TEMs are connected topologically,and the series and parallel thermoelectric systems are studied.The series system can increase the output voltage,and the current depends on the smallest TEM,resulting in a certain power loss,if any TEM is greater than the safe operating temperature,the system stops working;In the parallel system,5 TEMs are arranged independently along the heat exchanger to ensure that each TEM works independently.