Numerical Study Of Porous Media Reactor For Methane Dry Reforming Driven By Solar Energy

Solar driven methane dry reforming is a cutting-edge technology that uses solar energy to consume two greenhouse gases CO₂and CH₄as reactants and produce higher-grade synthesis gas（H₂+CO）,which will play an important role in promoting the 2030 carbon peak and 2060 carbon neutral in China.Existing studies mainly have the following problems:1)In most studies the dry reforming of methane is driven by heat,and the studies on solar driving reaction are lack;2)More attention is paid to catalyst materials,while less studies on energy and mass transfer under the action of heat transfer and thermochemistry in the reactor.Therefore,the main work and academic contributions of this paper are as follows:（1）This study establishes a numerical simulation method for coupling the solar heat collection process（heat conduction/convection/radiation coupling heat transfer）of the porous media reactor and the thermochemical reaction process of methane dry reforming.A large number of user-defined functions have been written to solve key simulation methods such as local non-thermal equilibrium,changing physical properties of working fluid,and dull cell matching between fluid domain and solid domain.The simulation results of typical operating condition are in good agreement with the experimental data.（2）Aiming at the heat collection process of the porous medium reactor,this paper studies the effects of the empirical correlations for convection coefficient and the extinction coefficient models on thermal efficiency for the first time.By analyzing 7 kinds of convection heat transfer coefficient correlation equations and 3 kinds of extinction coefficient models that frequently used in studies,the results show that various extinction coefficient models have less impact on simulation results,the largest difference in thermal efficiency is more than 10 percentage points.The impact of various convection heat transfer coefficient correlation equations is huge,with the difference closing to 28 percentage points at most.Therefore,this paper believes that more in-depth basic researches on convection and radiation heat transfer in porous media and more accurate heat transfer models are necessarily needed.（3）This paper carries out the analysis and study on the factors affecting the performance of solar driving methane dry reforming reaction based on porous media reactors.The factors include reaction conditions（reactant inlet velocity,composition ratio,distribution of solar radiation energy flow）,porous media basic characteristic parameters（porosity,pore size）and structure parameters of reactor.The performance standards include conversion efficiency of solar energy to chemical energy and the conversion rate of CO₂and CH₄.After the optimization,the energy conversion efficiency can be increased by more than 6 percentage points.A detailed energy loss analysis is carried out for the optimal working conditions,which will provide direction for further studies on improving energy conversion efficiency of solar energy to chemical energy.