A computer-aided ionic liquid design(CAILD) study is presented for the frequently encountered alkane/cycloalkane separations in petrochemical industry. Exhaustive experimental data are first collected to extend the UN...A computer-aided ionic liquid design(CAILD) study is presented for the frequently encountered alkane/cycloalkane separations in petrochemical industry. Exhaustive experimental data are first collected to extend the UNIFAC-IL model for this system, where the proximity effect in alkanes and cycloalkanes is considered specifically by defining distinct groups. The thermodynamic performances of a large number of ILs for 4 different alkane/cycloalkane systems are then compared to select a representative example of such separations. By applying n-heptane/methylcyclohexane extractive distillation as a case study, the CAILD task is cast as a mixed-integer nonlinear programming(MINLP) problem based on the obtained task-specific UNIFAC-IL model and two semi-empirical models for IL physical properties. The top 5 IL candidates determined by solving the MINLP problem are subsequently introduced into Aspen Plus for process simulation and economic analysis, which finally identify 1-hexadecyl-methylpiperidinium tricyanomethane([C_(16)MPip][C(CN)_3]) as the best entrainer for this separation.展开更多
For the design of eutectic solvents(ESs,usually also known as deep eutectic solvents),the prediction of the solid–liquid equilibria(SLE)between candidate components is of primary relevance.In the present work,the SLE...For the design of eutectic solvents(ESs,usually also known as deep eutectic solvents),the prediction of the solid–liquid equilibria(SLE)between candidate components is of primary relevance.In the present work,the SLE prediction of binary eutectic solvent systems by the COSMO-RS model is systematically evaluated,thereby examining the applicability of this method for ES design.Experimental SLE of such systems are first collected exhaustively from the literature,following which COSMO-RS SLE calculations are accordingly carried out.By comparing the experimental and predicted eutectic points(eutectic temperature and eutectic composition)of the involved systems,the effects of salt component conformer and COSMO-RS parameterization as well as the applicability for different types of components(specifically the second component paired with the first salt one)are identified.The distinct performances of COSMO-RS SLE prediction for systems involving different types of components are further interpreted from the non-ideality and fusion enthalpy point of view.展开更多
A novel C/Pb composite has been successfully prepared by electmless plating to reduce the hydrogenevolution and achieve the high reversibility of the anode of lead-carbon battery （LCB）. The depositedlead on the surf...A novel C/Pb composite has been successfully prepared by electmless plating to reduce the hydrogenevolution and achieve the high reversibility of the anode of lead-carbon battery （LCB）. The depositedlead on the surface of C/Pb composite was found to be uniform and adherent to carbon surface. Becauselead has been stuck on the surface of C/Pb composite, the embedded structure suppresses the hydrogenevolution of lead-carbon anode and strengthens the connection between carbon additive and sponge lead.Compared with the blank anode, the lead-carbon anode with C/Pb composite displays excellent charge-discharge reversibility, which is attributed to the good connection between carbon additives and leadthat has been stuck on the surface of C/Pb composite during the preparation process. The addition of CIPb composite maintains a solid anode structure with high specific surface area and power volume, andthereby, it plays a significant role in the highly reversible lead-carbon anode.展开更多
The selection of phase change material(PCM)plays an important role in developing high-efficient thermal energy storage(TES)processes.Ionic liquids(ILs)or organic salts are thermally stable,non-volatile,and non-flammab...The selection of phase change material(PCM)plays an important role in developing high-efficient thermal energy storage(TES)processes.Ionic liquids(ILs)or organic salts are thermally stable,non-volatile,and non-flammable.Importantly,researchers have proved that some ILs possess higher latent heat of fusion than conventional PCMs.Despite these attractive characteristics,yet surprisingly,little research has been performed to the systematic selection or structural design of ILs for TES.Besides,most of the existing work is only focused on the latent heat when selecting PCMs.However,one should note that other properties such as heat capacity and thermal conductivity could affect the TES performance as well.In this work,we propose a computer-aided molecular design(CAMD)based method to systematically design IL PCMs for a practical TES process.The effects of different IL properties are simultaneously captured in the IL property models and TES process models.Optimal ILs holding a best compromise of all the properties are identified through the solution of a formulated CAMD problem where the TES performance of the process is maximized.[MPyEtOH][TfO]is found to be the best material and excitingly,the identified top nine ILs all show a higher TES performance than the traditional PCM paraffin wax at 10 h thermal charging time.展开更多
Evolutionary algorithm is applied for distillation separation sequence optimization synthesis problems with combination explosion. The binary tree data structure is used to describe the distillation separation sequenc...Evolutionary algorithm is applied for distillation separation sequence optimization synthesis problems with combination explosion. The binary tree data structure is used to describe the distillation separation sequence, and it is directly applied as the coding method. Genetic operators, which ensure to prohibit illegal filial generations completely, are designed by using the method of graph theory. The crossover operator based on a single parent or two parents is designed successfully. The example shows that the average ratio of search space from evolutionary algorithm with two-parent genetic operation is lower, whereas the rate of successful minimizations from evolutionary algorithm with single parent genetic operation is higher.展开更多
Lead-carbon hybrid capacitors are the electrochemical devices between supercapacitors and lead-acid batteries,with low prices,stability in high and low temperature,good security and broad application prospects.This pa...Lead-carbon hybrid capacitors are the electrochemical devices between supercapacitors and lead-acid batteries,with low prices,stability in high and low temperature,good security and broad application prospects.This paper introduces an electrodeposition behavior of Pb^(2+)on the negative electrode,which can improve the cycle life of the lead-carbon hybrid capacitor.During the charging process,lead ions in the electrolyte can diffuse from the positive electrode of the lead-carbon hybrid capacitor into the negative electrode.When charging at a low current density,the lead ions around the negative electrode can be reduced to lead,and it is then quickly converted to lead sulfate crystals.With the increase of the number of cycles,the final result is sulfation.Sulfation can reduce the specific surface area of the electric double layer,thereby reducing the capacitance performance of the carbon material.As a result,it reduces the charge-discharge efficiency of the lead-carbon hybrid capacitor.The service life of lead-carbon hybrid capacitor is significantly improved by the inhibition of lead deposition by anion exchange membrane.The capacity retention rate at 5 A/g is improved from 84%after 1000 cycles to 95%after 10,000 cycles.The discovery of lead deposition in the negative electrode is conducive to improving the performance of long-life lead-carbon hybrid capacitors.展开更多
The inversion formula for conservative multifractal measures was unveiled mathematically a decade ago, which is however not well tested in real complex systems. We propose to verify the inversion formula using high-fr...The inversion formula for conservative multifractal measures was unveiled mathematically a decade ago, which is however not well tested in real complex systems. We propose to verify the inversion formula using high-frequency turbulent financial data. We construct conservative volatility measure based on minutely S＆P 500 index from 1982 to 1999 and its inverse measure of exit time. Both the direct and inverse measures exhibit nice multifractal nature, whose sealing ranges are not irrelevant. Empirical investigation shows that the inversion formula holds in financial markets.展开更多
基金financial support from National Natural Science Foundation of China(21776074,21576081,and21861132019)
文摘A computer-aided ionic liquid design(CAILD) study is presented for the frequently encountered alkane/cycloalkane separations in petrochemical industry. Exhaustive experimental data are first collected to extend the UNIFAC-IL model for this system, where the proximity effect in alkanes and cycloalkanes is considered specifically by defining distinct groups. The thermodynamic performances of a large number of ILs for 4 different alkane/cycloalkane systems are then compared to select a representative example of such separations. By applying n-heptane/methylcyclohexane extractive distillation as a case study, the CAILD task is cast as a mixed-integer nonlinear programming(MINLP) problem based on the obtained task-specific UNIFAC-IL model and two semi-empirical models for IL physical properties. The top 5 IL candidates determined by solving the MINLP problem are subsequently introduced into Aspen Plus for process simulation and economic analysis, which finally identify 1-hexadecyl-methylpiperidinium tricyanomethane([C_(16)MPip][C(CN)_3]) as the best entrainer for this separation.
基金the support of the Sino-German joint research project leaded by Deutsche Forschungsgemeinshaft(DFG)National Natural Science Foundation of China(NSFC)under the grants SU 189/9-1 and 21861132019,respectively
文摘For the design of eutectic solvents(ESs,usually also known as deep eutectic solvents),the prediction of the solid–liquid equilibria(SLE)between candidate components is of primary relevance.In the present work,the SLE prediction of binary eutectic solvent systems by the COSMO-RS model is systematically evaluated,thereby examining the applicability of this method for ES design.Experimental SLE of such systems are first collected exhaustively from the literature,following which COSMO-RS SLE calculations are accordingly carried out.By comparing the experimental and predicted eutectic points(eutectic temperature and eutectic composition)of the involved systems,the effects of salt component conformer and COSMO-RS parameterization as well as the applicability for different types of components(specifically the second component paired with the first salt one)are identified.The distinct performances of COSMO-RS SLE prediction for systems involving different types of components are further interpreted from the non-ideality and fusion enthalpy point of view.
基金the financial support provided by the National Natural Science Foundation of China (No.21573093)the National Key Research and Development Program (No.2017YFB0307501)Guangdong Innovative and Entrepreneurial Research Team Program (No.2013C092)
文摘A novel C/Pb composite has been successfully prepared by electmless plating to reduce the hydrogenevolution and achieve the high reversibility of the anode of lead-carbon battery （LCB）. The depositedlead on the surface of C/Pb composite was found to be uniform and adherent to carbon surface. Becauselead has been stuck on the surface of C/Pb composite, the embedded structure suppresses the hydrogenevolution of lead-carbon anode and strengthens the connection between carbon additive and sponge lead.Compared with the blank anode, the lead-carbon anode with C/Pb composite displays excellent charge-discharge reversibility, which is attributed to the good connection between carbon additives and leadthat has been stuck on the surface of C/Pb composite during the preparation process. The addition of CIPb composite maintains a solid anode structure with high specific surface area and power volume, andthereby, it plays a significant role in the highly reversible lead-carbon anode.
基金the financial support from Max Planck Society,Germany,for the Computer-Aided Material and Process Design(CAMPD)project
文摘The selection of phase change material(PCM)plays an important role in developing high-efficient thermal energy storage(TES)processes.Ionic liquids(ILs)or organic salts are thermally stable,non-volatile,and non-flammable.Importantly,researchers have proved that some ILs possess higher latent heat of fusion than conventional PCMs.Despite these attractive characteristics,yet surprisingly,little research has been performed to the systematic selection or structural design of ILs for TES.Besides,most of the existing work is only focused on the latent heat when selecting PCMs.However,one should note that other properties such as heat capacity and thermal conductivity could affect the TES performance as well.In this work,we propose a computer-aided molecular design(CAMD)based method to systematically design IL PCMs for a practical TES process.The effects of different IL properties are simultaneously captured in the IL property models and TES process models.Optimal ILs holding a best compromise of all the properties are identified through the solution of a formulated CAMD problem where the TES performance of the process is maximized.[MPyEtOH][TfO]is found to be the best material and excitingly,the identified top nine ILs all show a higher TES performance than the traditional PCM paraffin wax at 10 h thermal charging time.
文摘Evolutionary algorithm is applied for distillation separation sequence optimization synthesis problems with combination explosion. The binary tree data structure is used to describe the distillation separation sequence, and it is directly applied as the coding method. Genetic operators, which ensure to prohibit illegal filial generations completely, are designed by using the method of graph theory. The crossover operator based on a single parent or two parents is designed successfully. The example shows that the average ratio of search space from evolutionary algorithm with two-parent genetic operation is lower, whereas the rate of successful minimizations from evolutionary algorithm with single parent genetic operation is higher.
基金supported by the National Natural Science Foundation of China,China(No.21975101)Science and Technology Innovation Team Project of Jilin University,China(No.2017TD31)Major Science and Technology Research Project of “Shuangshi Project”in Changchun City,China(No.17SS018)。
文摘Lead-carbon hybrid capacitors are the electrochemical devices between supercapacitors and lead-acid batteries,with low prices,stability in high and low temperature,good security and broad application prospects.This paper introduces an electrodeposition behavior of Pb^(2+)on the negative electrode,which can improve the cycle life of the lead-carbon hybrid capacitor.During the charging process,lead ions in the electrolyte can diffuse from the positive electrode of the lead-carbon hybrid capacitor into the negative electrode.When charging at a low current density,the lead ions around the negative electrode can be reduced to lead,and it is then quickly converted to lead sulfate crystals.With the increase of the number of cycles,the final result is sulfation.Sulfation can reduce the specific surface area of the electric double layer,thereby reducing the capacitance performance of the carbon material.As a result,it reduces the charge-discharge efficiency of the lead-carbon hybrid capacitor.The service life of lead-carbon hybrid capacitor is significantly improved by the inhibition of lead deposition by anion exchange membrane.The capacity retention rate at 5 A/g is improved from 84%after 1000 cycles to 95%after 10,000 cycles.The discovery of lead deposition in the negative electrode is conducive to improving the performance of long-life lead-carbon hybrid capacitors.
基金Supported by the National Natural Science Foundation of China under Grant No 70501011, the Fok Ying Tong Education Foundation under Grant No 101086, and the Programme for New Century Excellent Talents in University under Grant No NCET- 07-0288.
文摘The inversion formula for conservative multifractal measures was unveiled mathematically a decade ago, which is however not well tested in real complex systems. We propose to verify the inversion formula using high-frequency turbulent financial data. We construct conservative volatility measure based on minutely S＆P 500 index from 1982 to 1999 and its inverse measure of exit time. Both the direct and inverse measures exhibit nice multifractal nature, whose sealing ranges are not irrelevant. Empirical investigation shows that the inversion formula holds in financial markets.
