The performance of a novel conical-type downer pyrolyzer is carefully evaluated via numerical simulation.The study explicitly accounts for mass transfer effects by using a multi-scale mass transfer model.To achieve si...The performance of a novel conical-type downer pyrolyzer is carefully evaluated via numerical simulation.The study explicitly accounts for mass transfer effects by using a multi-scale mass transfer model.To achieve simultaneous high precision and computational efficiency,an enhanced strategy for calculating the multi-scale mass transfer coefficient in heterogeneous phase reaction systems is proposed by treating mass transfer and reaction as independent processes.This strategy is coupled with a discrete distributed activation energy model formulated in the Arrhenius framework.A comprehensive analysis is performed to investigate the axial distributions of key parameters,including the average concentration of solid reactants(X_(s)),the volatile concentration on particle surfaces(X_(sf)),and the volatile concentration in the bulk gas phase(X_(f))under varying pyrolysis temperatures,carrier gas velocities,and solid mass fluxes.The findings reveal that Xs and Xf exhibit intuitive,monotonic trends,while Xsf demonstrates a more complex behavior,increasing due to ongoing reactions yet decreasing with mass transfer proceeding.The simulation results verify the advantages of the conical-type downer pyrolyzer,which can achieve significantly higher volatile concentrations than conventional designs.展开更多
基金supported by the National Natural Science Foundation of China(grant Nos.22108262,22378285)China Scholarship Council(grant Nos.202308140163,202306930019),Fundamental Research Program of Shanxi Province(grant No.20210302124600)+1 种基金Research Project Supported by Shanxi Scholarship Council of China(grant No.2022-138)Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(grant No.20220014).
文摘The performance of a novel conical-type downer pyrolyzer is carefully evaluated via numerical simulation.The study explicitly accounts for mass transfer effects by using a multi-scale mass transfer model.To achieve simultaneous high precision and computational efficiency,an enhanced strategy for calculating the multi-scale mass transfer coefficient in heterogeneous phase reaction systems is proposed by treating mass transfer and reaction as independent processes.This strategy is coupled with a discrete distributed activation energy model formulated in the Arrhenius framework.A comprehensive analysis is performed to investigate the axial distributions of key parameters,including the average concentration of solid reactants(X_(s)),the volatile concentration on particle surfaces(X_(sf)),and the volatile concentration in the bulk gas phase(X_(f))under varying pyrolysis temperatures,carrier gas velocities,and solid mass fluxes.The findings reveal that Xs and Xf exhibit intuitive,monotonic trends,while Xsf demonstrates a more complex behavior,increasing due to ongoing reactions yet decreasing with mass transfer proceeding.The simulation results verify the advantages of the conical-type downer pyrolyzer,which can achieve significantly higher volatile concentrations than conventional designs.
