Thermo-electrical Performance And Optimization Of Phase Change Material-Thermoelectric Generator Envelope

Thermoelectric power generation technology can realize the direct conversion of thermal energy to electrical energy,and is often used for the recovery and utilization of low-grade heat sources.Because of the large heat capacity of phase change envelope,it can reduce energy consumption and improve the indoor environment.This thesis combines thermoelectric power generation technology and phase change(material)enclosure.The temperature,thermoelectric efficiency and optimization law of TEG,PCM-TEG,PCM-TEG Envelope were studied respectively.The relation of maximum output power and thermoelectric conversion efficiency of TEG with temperature difference is obtained.The power output and optimal load of different combinations of TEG in monolithic,series and parallel are studied.It is found that the power output law of multiple TEGs in different combinations is basically the same as that of DC power supply,and the optimal load is combined with the equivalent internal resistance of TEG in series and parallel.A heat transfer enhancement study on the cold and hot sides of PCM-TEG was carried out,including the effects of phase change temperature,volume and thermal conductivity of PCM.By enhancing the radiation and improving convection conditions of the hot and cold sides of PCM-TEG,the output power is improved.The phase change temperature of PCM is preferably equal to the average of working temperature of TEG;the electric energy output of PCM-TEG increases with increase of the thickness of the PCM;with the increase of the thermal conductivity of PCM,electric energy output is also increased,and have an optimal thermal conductivity value.The addition of expanded graphite to the PCM can increase the power output of GPCM-TEG,with a maximum increase of 143%(addition amount of 1%).After smearing carbon black on the surface of TEG,the CGPCM-TEG power generation increased by 3-5 times compared with the untreated one;enhance the convection heat transfer coefficient of TEG surface during the night is beneficial to power generation of TEG,but slightly.A numerical model of PCM-TEG Enclosure was established by Fluent.Temperature,liquid fraction of PCM and power generation with different PCM thermal parameters,radiation absorption coefficients,heat transfer coefficients,and reasons were studied.The study found that the lower the phase transition temperature range,the higher the liquid phase ratio of PCM and power output of TEG.The surface of TEG coated with carbon black can increase the output of electrical energy,and also cause an increase in indoor temperature fluctuation range.Considering a better indoor temperature environment and energy output,increace the TEG outer surface absorption ratio and reduce the convection heat transfer coefficient during the day in spring,autumn,and winter,and only enhance the absorption ratio in summer.In the end,spring has the greatest potential for electrical energy output,followed by autumn,summer,and winter.Combining thermoelectric power generation technology with phase change envelope can not only reduce building energy consumption,but also generate electrical energy by using solar energy or building waste heat,which has good application prospects.There are 68 Figures,26 Tables,and 77 references in this thesis.