Study On The Electro-osmotic Characteristics Of Solid Desiccant

Achieving carbon peak as soon as possible and finally achieve carbon neutrality is the goal of China’s energy structure adjustment and development to actively realize clean and lowcarbon energy.The independent control technology of temperature and humidity can meet the requirements of indoor temperature and humidity at the same time,and reduce the overall energy consumption.The use of electro-osmotic effect to regenerate the solid desiccant in the independent control system of temperature and humidity has the advantages of clean,efficient and easy operation.Therefore,this thesis aims to analyze the formation and development of electro-osmotic flow(EOF)in two types of solid desiccant,and discuss the main impact factors by using lattice Boltzmann method(LBM),which provide theoretical guidance for the development of electro-osmotic dehumidification technology.First,this thesis introduces the EOF experiments of two common solid desiccants(macroporous silica gel,activated alumina)under high saturation condition,which can not only provide references for the validation of subsequent models,but also used for the analysis of energy consumption in such procedure.Then,a homogeneous electro-osmotic model of solid desiccant(hereinafter: homogeneous model)is established to describe the structure of solid desiccant with homogeneous skeleton distribution by LBM.Material related impact factors(voidage,tortuosity,solid particle diameter,zeta potential)and environment related impact factors(applied electric field intensity)are studied on the variations of EOF.Because the homogeneous model can’t reflect details of pore structure,such as the distribution of pore sizes and connectivity of pores,two types of reconstruction methods are proposed for inhomogeneous solid desiccants: the Sierpinski carpet model which is based on the accurate self-similarity and the quartet structure generation set(QSGS)model which is based on random strategy.By comparing the simulation results derived from such two methods,the QSGS model is selected(hereinafter: inhomogeneous model)for further investigation.The impact factors selected in the inhomogeneous model are voidage,pore size,zeta potential(material related impact factors),as well as ion concentration and applied electric field intensity(environment related impact factors).Based on the variations of multiple impact factors,an optimization strategy is proposed to derive desired parameters of the two studied solid desiccants,which can theoretically reach the optimal EOF rates.The specific findings are summarized as follows.By analyzing the experimental data,it is found that the Specific Moisture Extraction Rate(SMER)of dehumidification of macroporous silica gel is between 11.306kg/k Wh and 22.783kg/k Wh,while the value of activated alumina is between 5.341kg/k Wh and 13.265kg/k Wh,the solid desiccant can be selected according to the application conditions.Based on the homogeneous model,it is found that voidage is the most sensitive factor for both macroporous silica gel and activated alumina:when voidage fluctuates ±20%,the EOF rate of the macroporous silica gel changes 53.3%,and that of activated alumina changes 44.9%.Based on the inhomogeneous model,it is found that the applied electric field intensity and zeta potential are the most sensitive factors of the macroporous silica gel and activated alumina,respectively.By varying the reference value around ±20%,the EOF rate caused by the variation is 40.25% and 39.58%,respectively.It is the differences in the details of the structure that lead to the inconsistence of the sensitivity.Appropriate models can be selected based on the actual requirements.By considering the inhomogeneous model with QSGS structure,a single-objective optimization is derived from genetic algorithm and the preferred values of related parameters are summarized to achieve optimal EOF rates.