In 1949, Tolman found the relation between the surface tension and Tolman length, which determines the dimensional effect of the surface tension. Tolman length is the difference between the equimolar surface and the s...In 1949, Tolman found the relation between the surface tension and Tolman length, which determines the dimensional effect of the surface tension. Tolman length is the difference between the equimolar surface and the surface of tension. In recent years, the magnitude, expression, and sign of the Tolman length remain an open question. An incompressible and homogeneous liquid droplet model is proposed and the approximate expression and sign for Tolman length are derived in this paper. We obtain the relation between Tolman length and the radius of the surface of tension(R_(s)) and found that they increase with the Rs decreasing. The Tolman length of plane surface tends to zero. Taking argon for example, molecular dynamics simulation is carried out by using the Lennard–Jones(LJ) potential between atoms at a temperature of 90 K. Five simulated systems are used, with numbers of argon atoms being 10140, 10935, 11760, 13500, and 15360, respectively. By methods of theoretical study and molecular dynamics simulation, we find that the calculated value of Tolman length is more than zero, and it decreases as the size is increased among the whole size range. The value of surface tension increases with the radius of the surface of tension increasing, which is consistent with Tolman’s theory. These conclusions are significant for studying the size dependence of the surface tension.展开更多
Biomass is a renewable energy source helps reduce greenhouse gas emissions.However,combustion and reaction efficiency of biomass are significantly affected by their flow behavior.In this study,the flow characteristics...Biomass is a renewable energy source helps reduce greenhouse gas emissions.However,combustion and reaction efficiency of biomass are significantly affected by their flow behavior.In this study,the flow characteristics of wet elongated biomass particles in a lifting tube were experimentally investigated.Particle Tracking Velocimetry(PTV)was used to explore the particle area and velocity distribution under different gas-to-particle mass ratios(GPMR)and initial moisture contents(IMC).A homogeneity coefficient was also formulated to quantify the flow homogeneity of the particle population.The calculated range for the homogeneity coefficientαis 4.43-6.40,with smaller values indicating better flow homogeneity.Moreover,the factors affecting the fragmentation of larger particle clusters were analyzed with respect to the suspension process,the process of being carried out by the airflow,and the fragmentation process.The results indicated that the flow homogeneity of the particle population was better in the two sets of conditions when IMC was 28.7% and GPMR was 10 and when IMC was 32.5% and GPMR was 9.The homogeneity coefficient α was 4.43 and 4.79.In addition,the degree of fragmentation of larger particle clusters is mainly affected by the IMC.展开更多
The effects of the diameters of single-walled carbon nanotubes （SWCNTs） （7.83A to 27.40A） and temperature （20 K-45 K） on the equilibrium structure of an argon cluster are systematically studied by molecular dyna...The effects of the diameters of single-walled carbon nanotubes （SWCNTs） （7.83A to 27.40A） and temperature （20 K-45 K） on the equilibrium structure of an argon cluster are systematically studied by molecular dynamics simulation with consideration of the SWCNTs to be fixed. Since the diameters of SWCNTs with different chiralities increase when temperature is fixed at 20 K, the equilibrium structures of the argon cluster transform from monoatomic chains to helical and then to multishell coaxial cylinders. Chirality has almost no noticeable influence on these cylindrosymmetric structures. The effects of temperature and a non-equilibrium sudden heating process on the structures of argon clusters in SWCNTs are also studied by molecular dynamics simulation.展开更多
The Tolman length δ 0 of a liquid with a plane surface has attracted increasing theoretical attention in recent years,but the expression of Tolman length in terms of observable quantities is still not very clear.In 2...The Tolman length δ 0 of a liquid with a plane surface has attracted increasing theoretical attention in recent years,but the expression of Tolman length in terms of observable quantities is still not very clear.In 2001,Bartell gave a simple expression of Tolman length δ 0 in terms of isothermal compressibility.However,this expression predicts that Tolman length is always negative,which is contrary to the results of molecular dynamics simulations（MDS） for simple liquids.In this paper,this contradiction is analyzed and the reason for the discrepancy in the sign is found.In addition,we introduce a new expression of Tolman length in terms of isothermal compressibility for simple fluids not near the critical points under some weak restrictions.The Tolman length of simple liquids calculated by using this formula is consistent with that obtained using MDS regarding the sign.展开更多
A bended ribbon biomass particle model was developed to explore the dynamic transport properties inside a riser reactor.Residence time distribution(RTD)of the particles was analyzed by using the Eulerian-Lagrange meth...A bended ribbon biomass particle model was developed to explore the dynamic transport properties inside a riser reactor.Residence time distribution(RTD)of the particles was analyzed by using the Eulerian-Lagrange method.The effects of sampling height,particle density,particle size and gas-to-solid mass ratio on RTD were investigated.The coupled Computational Fluid Dynamics and Discrete Element Method(CFD-DEM)model was verified firstly by experimental data on pressure drop and residence time distribution density function.The simulation results demonstrated that the ribbon biomass particles display a typical annular-core spatial distribution during transportation.The RTD of particles exhibit an approximate single-peaked normal distribution.The mean residence time(MRT)can reach up to 0.7 s when the particle density is 1200 kg/m^(3).Particle with higher density has longer mean residence time.The flow patterns are closer to plug flow if particle length over 12 mm.The particle flow pattern is not sensitive to changes in particle density and size,while the gas-to-material mass ratio has a significant impact on it.展开更多
For all-solid-state lithium batteries(ASSLBs),polymer-blended solid composite electrolytes(SCEs)have drawn wide interest owing to their significance in improving the interfacial solid-solid contacts and inhibiting the...For all-solid-state lithium batteries(ASSLBs),polymer-blended solid composite electrolytes(SCEs)have drawn wide interest owing to their significance in improving the interfacial solid-solid contacts and inhibiting the growth of lithium dendrites.In this work,SCEs based on PVDF-HFP/PMMA matrix containing MOFs(NH2-MIL-53(Al))and LiTFSI were designed and synthesized employing an easy solution casting method.The synthesized samples were examined by XRD,SEM,EDS,and electrochemical tests.It was found that MPP-2 SCE not only has excellent ionic conductivity at 60℃ of 5.54×10^(−4) S cm^(−1),but also exhibits superior interfacial compatibility in Li||Li symmetric batteries,which can constantly cycle for about 800 h at 0.1 mA cm^(−2) with no short-circuiting.The assembled Li|MPP-2|LiFePO4 cell exhibited a first discharge specific capacity of up to 157.1 mAh g^(−1) at 60℃ and 0.2 C.This work may help to further advance the progress of ASSLBs in the future.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFB0700500)the Scientific Research and Innovation Team of Cangzhou Normal University,China(Grant No.cxtdl1907)+2 种基金the Key Scientific Study Program of Hebei Provincial Higher Education Institution,China(Grant No.ZD2020410)the Cangzhou Natural Science Foundation,China(Grant No.197000001)the General Scientific Research Fund Project of Cangzhou Normal University,China(Grant No.xnjjl1906)。
文摘In 1949, Tolman found the relation between the surface tension and Tolman length, which determines the dimensional effect of the surface tension. Tolman length is the difference between the equimolar surface and the surface of tension. In recent years, the magnitude, expression, and sign of the Tolman length remain an open question. An incompressible and homogeneous liquid droplet model is proposed and the approximate expression and sign for Tolman length are derived in this paper. We obtain the relation between Tolman length and the radius of the surface of tension(R_(s)) and found that they increase with the Rs decreasing. The Tolman length of plane surface tends to zero. Taking argon for example, molecular dynamics simulation is carried out by using the Lennard–Jones(LJ) potential between atoms at a temperature of 90 K. Five simulated systems are used, with numbers of argon atoms being 10140, 10935, 11760, 13500, and 15360, respectively. By methods of theoretical study and molecular dynamics simulation, we find that the calculated value of Tolman length is more than zero, and it decreases as the size is increased among the whole size range. The value of surface tension increases with the radius of the surface of tension increasing, which is consistent with Tolman’s theory. These conclusions are significant for studying the size dependence of the surface tension.
基金thefinancial support of the National Natural Science Foundation of China(grant No.51906092)Postgraduate Research&Practice Innovation Program of Jiangsu Province(grant No.SJCX23_2219).
文摘Biomass is a renewable energy source helps reduce greenhouse gas emissions.However,combustion and reaction efficiency of biomass are significantly affected by their flow behavior.In this study,the flow characteristics of wet elongated biomass particles in a lifting tube were experimentally investigated.Particle Tracking Velocimetry(PTV)was used to explore the particle area and velocity distribution under different gas-to-particle mass ratios(GPMR)and initial moisture contents(IMC).A homogeneity coefficient was also formulated to quantify the flow homogeneity of the particle population.The calculated range for the homogeneity coefficientαis 4.43-6.40,with smaller values indicating better flow homogeneity.Moreover,the factors affecting the fragmentation of larger particle clusters were analyzed with respect to the suspension process,the process of being carried out by the airflow,and the fragmentation process.The results indicated that the flow homogeneity of the particle population was better in the two sets of conditions when IMC was 28.7% and GPMR was 10 and when IMC was 32.5% and GPMR was 9.The homogeneity coefficient α was 4.43 and 4.79.In addition,the degree of fragmentation of larger particle clusters is mainly affected by the IMC.
基金Project supported by the National Natural Science Foundation of China(Grant No.11072242)
文摘The effects of the diameters of single-walled carbon nanotubes （SWCNTs） （7.83A to 27.40A） and temperature （20 K-45 K） on the equilibrium structure of an argon cluster are systematically studied by molecular dynamics simulation with consideration of the SWCNTs to be fixed. Since the diameters of SWCNTs with different chiralities increase when temperature is fixed at 20 K, the equilibrium structures of the argon cluster transform from monoatomic chains to helical and then to multishell coaxial cylinders. Chirality has almost no noticeable influence on these cylindrosymmetric structures. The effects of temperature and a non-equilibrium sudden heating process on the structures of argon clusters in SWCNTs are also studied by molecular dynamics simulation.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11072242)
文摘The Tolman length δ 0 of a liquid with a plane surface has attracted increasing theoretical attention in recent years,but the expression of Tolman length in terms of observable quantities is still not very clear.In 2001,Bartell gave a simple expression of Tolman length δ 0 in terms of isothermal compressibility.However,this expression predicts that Tolman length is always negative,which is contrary to the results of molecular dynamics simulations（MDS） for simple liquids.In this paper,this contradiction is analyzed and the reason for the discrepancy in the sign is found.In addition,we introduce a new expression of Tolman length in terms of isothermal compressibility for simple fluids not near the critical points under some weak restrictions.The Tolman length of simple liquids calculated by using this formula is consistent with that obtained using MDS regarding the sign.
基金support of the National Natural Science Foundation of China (grant No.51906092)China Tobacco Jiangxi Industrial Corporation Limited.
文摘A bended ribbon biomass particle model was developed to explore the dynamic transport properties inside a riser reactor.Residence time distribution(RTD)of the particles was analyzed by using the Eulerian-Lagrange method.The effects of sampling height,particle density,particle size and gas-to-solid mass ratio on RTD were investigated.The coupled Computational Fluid Dynamics and Discrete Element Method(CFD-DEM)model was verified firstly by experimental data on pressure drop and residence time distribution density function.The simulation results demonstrated that the ribbon biomass particles display a typical annular-core spatial distribution during transportation.The RTD of particles exhibit an approximate single-peaked normal distribution.The mean residence time(MRT)can reach up to 0.7 s when the particle density is 1200 kg/m^(3).Particle with higher density has longer mean residence time.The flow patterns are closer to plug flow if particle length over 12 mm.The particle flow pattern is not sensitive to changes in particle density and size,while the gas-to-material mass ratio has a significant impact on it.
基金supported by National Natural Science Foundation of China(grant Nos.21701083,22179054)The Ministry of Science and Technology of the People's Republic of China(grant No.G2023014022L)Jiangsu Provincial Key Research and Development Program(grant No.BZ2023010).
文摘For all-solid-state lithium batteries(ASSLBs),polymer-blended solid composite electrolytes(SCEs)have drawn wide interest owing to their significance in improving the interfacial solid-solid contacts and inhibiting the growth of lithium dendrites.In this work,SCEs based on PVDF-HFP/PMMA matrix containing MOFs(NH2-MIL-53(Al))and LiTFSI were designed and synthesized employing an easy solution casting method.The synthesized samples were examined by XRD,SEM,EDS,and electrochemical tests.It was found that MPP-2 SCE not only has excellent ionic conductivity at 60℃ of 5.54×10^(−4) S cm^(−1),but also exhibits superior interfacial compatibility in Li||Li symmetric batteries,which can constantly cycle for about 800 h at 0.1 mA cm^(−2) with no short-circuiting.The assembled Li|MPP-2|LiFePO4 cell exhibited a first discharge specific capacity of up to 157.1 mAh g^(−1) at 60℃ and 0.2 C.This work may help to further advance the progress of ASSLBs in the future.
