In this work grand canonical Monte Carlo simulations were performed to study gas separation in three pairs of isoreticular metal-organic frameworks (IRMOFs) with and without catenation at room temperature.Mixture comp...In this work grand canonical Monte Carlo simulations were performed to study gas separation in three pairs of isoreticular metal-organic frameworks (IRMOFs) with and without catenation at room temperature.Mixture composed of CO2 and H2 was selected as the model system to separate.The results show that CO2 selectivity in catenated MOFs with multi-porous frameworks is much higher than their non-catenated counterparts.The simulations also show that the electrostatic interactions are very important for the selectivity,and the contributions of different electrostatic interactions are different,depending on pore size,pressure and mixture composition.In fact,changing the electrostatic interactions can even qualitatively change the adsorption behavior.A general conclusion is that the electrostatic interactions between adsorbate molecules and the framework atoms play a dominant role at low pressures,and these interactions in catenated MOFs have much more pronounced effects than those in their non-catenated counterparts,while the electrostatic interactions between adsorbate molecules become evident with increasing pressure,and eventually dominant.展开更多
The energy-conserving performance of dividing wall column(DWC) is discussed in this paper. The heat transfer through the dividing wall is considered and the results are compared with that of common heat insulation div...The energy-conserving performance of dividing wall column(DWC) is discussed in this paper. The heat transfer through the dividing wall is considered and the results are compared with that of common heat insulation dividing wall column(HIDWC). Based on the thermodynamic analysis of heat transfer dividing wall column(HTDWC) and HIDWC, both computer simulation and experiments are employed to analyze the energyconserving situation. Mixtures of n-hexane, n-heptane and n-octane are chosen as the example for separation.The results show that the energy consumption of HTDWC is 50.3% less than that of conventional distillation column, while it is 46.4% less than that of HIDWC. It indicates that DWC is efficient on separating threecomponent mixtures and HTDWC can save more energy than HIDWC. Thus it is necessary to consider the heat transfer while applying DWC to industry.展开更多
The dynamic mechanical property of concrete is one of the key parameters,which greatly influences durability of infrastructures subjected to continuous heavy loading,such as girder and track slab of high-speed railway...The dynamic mechanical property of concrete is one of the key parameters,which greatly influences durability of infrastructures subjected to continuous heavy loading,such as girder and track slab of high-speed railway foundation structure.This paper reports serials of experiments designed to investigate the deterioration of dynamic mechanical properties of different concretes under fatigue loading condition.Four parameters including relative dynamic elastic modulus(RDEM),relative dynamic shear modulus(RDSM),relative compressive strength(RCS)and water absorption(WA)of concrete were evaluated to assess the dynamic properties and microstructures of concretes.Results show that the fatigue stress levels and fatigue cycle durations significantly influence the dynamic mechanical properties of concrete including dynamic elastic modulus and dynamic shear modulus.Addition of proper mineral admixture can improve the dynamic mechanical characteristics of concrete and increase its resistance against the fatigue loading effect.Keeping the amount of mineral admixture in concrete constant,its dynamic mechanical property with fly ash is lower than that with fly ash and silica fume.The water absorption in concrete,which is an indirect parameter reflecting capillary porosity,increases evidently after bearing fatigue-loading.There is a close correlation between the deterioration of dynamic mechanical property and the increasing of water absorption of concrete.This indicates that the damage of microstructure of concrete subjected to fatigue loading is the indispensable reason for the decay of its dynamic mechanical performance.展开更多
基金Supported by the National Natural Science Foundation of China （20725622, 20706002, and 20876006）, Beijing Nova Program （2008B15） and the Dutch STW/CW Separation Technology Program （700.56.655-DPC.6243）.
文摘In this work grand canonical Monte Carlo simulations were performed to study gas separation in three pairs of isoreticular metal-organic frameworks (IRMOFs) with and without catenation at room temperature.Mixture composed of CO2 and H2 was selected as the model system to separate.The results show that CO2 selectivity in catenated MOFs with multi-porous frameworks is much higher than their non-catenated counterparts.The simulations also show that the electrostatic interactions are very important for the selectivity,and the contributions of different electrostatic interactions are different,depending on pore size,pressure and mixture composition.In fact,changing the electrostatic interactions can even qualitatively change the adsorption behavior.A general conclusion is that the electrostatic interactions between adsorbate molecules and the framework atoms play a dominant role at low pressures,and these interactions in catenated MOFs have much more pronounced effects than those in their non-catenated counterparts,while the electrostatic interactions between adsorbate molecules become evident with increasing pressure,and eventually dominant.
基金Supported by the National Natural Science Foundation of China(21306036)Science&Technology Research Fund Project for Outstanding Youth in Colleges and Universities of Hebei province(Y2012040)the Joint Specialized Research Fund for the Doctoral Program of Higher Education of China(20131317120014)
文摘The energy-conserving performance of dividing wall column(DWC) is discussed in this paper. The heat transfer through the dividing wall is considered and the results are compared with that of common heat insulation dividing wall column(HIDWC). Based on the thermodynamic analysis of heat transfer dividing wall column(HTDWC) and HIDWC, both computer simulation and experiments are employed to analyze the energyconserving situation. Mixtures of n-hexane, n-heptane and n-octane are chosen as the example for separation.The results show that the energy consumption of HTDWC is 50.3% less than that of conventional distillation column, while it is 46.4% less than that of HIDWC. It indicates that DWC is efficient on separating threecomponent mixtures and HTDWC can save more energy than HIDWC. Thus it is necessary to consider the heat transfer while applying DWC to industry.
基金supported by the National Basic Research Program of China("973"Project)(Grant No.2013CB036201)
文摘The dynamic mechanical property of concrete is one of the key parameters,which greatly influences durability of infrastructures subjected to continuous heavy loading,such as girder and track slab of high-speed railway foundation structure.This paper reports serials of experiments designed to investigate the deterioration of dynamic mechanical properties of different concretes under fatigue loading condition.Four parameters including relative dynamic elastic modulus(RDEM),relative dynamic shear modulus(RDSM),relative compressive strength(RCS)and water absorption(WA)of concrete were evaluated to assess the dynamic properties and microstructures of concretes.Results show that the fatigue stress levels and fatigue cycle durations significantly influence the dynamic mechanical properties of concrete including dynamic elastic modulus and dynamic shear modulus.Addition of proper mineral admixture can improve the dynamic mechanical characteristics of concrete and increase its resistance against the fatigue loading effect.Keeping the amount of mineral admixture in concrete constant,its dynamic mechanical property with fly ash is lower than that with fly ash and silica fume.The water absorption in concrete,which is an indirect parameter reflecting capillary porosity,increases evidently after bearing fatigue-loading.There is a close correlation between the deterioration of dynamic mechanical property and the increasing of water absorption of concrete.This indicates that the damage of microstructure of concrete subjected to fatigue loading is the indispensable reason for the decay of its dynamic mechanical performance.
