The group-contribution (GC) methods suffer from a limitation concerning to the prediction of process-related indexes, e.g., thermal efficiency. Recently developed analytical models for thermal efficiency of organic Ra...The group-contribution (GC) methods suffer from a limitation concerning to the prediction of process-related indexes, e.g., thermal efficiency. Recently developed analytical models for thermal efficiency of organic Rankine cycles (ORCs) provide a possibility of overcoming the limitation of the GC methods because these models formulate thermal efficiency as functions of key thermal properties. Using these analytical relations together with GC methods, more than 60 organic fluids are screened for medium-low temperature ORCs. The results indicate that the GC methods can estimate thermal properties with acceptable accuracy (mean relative errors are 4.45%-11.50%);the precision, however, is low because the relative errors can vary from less than 0.1% to 45.0%. By contrast, the GC-based estimation of thermal efficiency has better accuracy and precision. The relative errors in thermal efficiency have an arithmetic mean of about 2.9% and fall within the range of 0-24.0%. These findings suggest that the analytical equations provide not only a direct way of estimating thermal efficiency but an accurate and precise approach to evaluating working fluids and guiding computer-aided molecular design of new fluids for ORCs using GC methods.展开更多
离子液体(ILs)具有高稳定性、溶解性能好、可设计性、易回收等优点,尤其因高CO_(2)溶解度在碳捕集方面显示了巨大潜力。但由于ILs种类繁多且价格昂贵,依靠实验研究耗时费力,因此构建ILs体系的热力学预测模型至关重要。UNIFAC模型在ILs...离子液体(ILs)具有高稳定性、溶解性能好、可设计性、易回收等优点,尤其因高CO_(2)溶解度在碳捕集方面显示了巨大潜力。但由于ILs种类繁多且价格昂贵,依靠实验研究耗时费力,因此构建ILs体系的热力学预测模型至关重要。UNIFAC模型在ILs气体分离工艺设计与优化领域具有重要的理论价值和工程应用意义,基于此,本研究构建了应用于ILs-CO_(2)体系活度系数预测的UNIFAC模型。本文系统收集了CO_(2)在ILs中的溶解度实验数据,并结合相平衡计算出活度系数,建立了ILs-CO_(2)体系活度系数数据库。采用COSMO方法和van der Waals规则分别获得了UNIFAC模型中基团的重要参数(R_(k)和Q_(k))。基于实验值,拟合了UNIFAC相互作用参数。通过平均相对误差(AARD),比较了两种方法建立的UNIFAC模型的预测效果。结果表明:通过COSMO方法(AARD=7.68%)建立的UNIFAC模型对ILs-CO_(2)体系的活度系数预测误差比van der Waals方法(AARD=12.57%)降低了4.89个百分点。并在此基础上建立了ILs-CO_(2)体系UNIFAC模型,获得了近100对基团的相互作用参数数据库。由于UNIFAC模型的基团贡献特点,本工作建立的UNIFAC模型可预测数据库中包含的基团组成的新型ILs与CO_(2)体系的活度系数,从而为后续ILs法气体吸收的分子设计奠定了扎实基础。展开更多
There are limited Vapor-Liquid Equilibrium（VLE） data in cluding N-formylmorpholine（NFM） for the design of the extractive distil lation process using NFM as solvent.The new interaction parameters of UNIFAC mo del w...There are limited Vapor-Liquid Equilibrium（VLE） data in cluding N-formylmorpholine（NFM） for the design of the extractive distil lation process using NFM as solvent.The new interaction parameters of UNIFAC mo del were fitted with experimental data between CH2,ACH and NFM which was rega rded as a main group.Comparison of the prediction results of VLE data and infin ite dilution activity coefficients with other published methods of group divisio n for NFM, indicated more satisfying results with the interaction parameters of this paper. The four methods of group division for NFM were discussed based on the group division for ring molecule and group charge distribution. The group c harge distribution at the minimum energy state was calculated by the AM1 method in Chem3D Pro. The good theoretical basis was presented for the group division of NFM.展开更多
基金Project(51778626) supported by the National Natural Science Foundation of China
文摘The group-contribution (GC) methods suffer from a limitation concerning to the prediction of process-related indexes, e.g., thermal efficiency. Recently developed analytical models for thermal efficiency of organic Rankine cycles (ORCs) provide a possibility of overcoming the limitation of the GC methods because these models formulate thermal efficiency as functions of key thermal properties. Using these analytical relations together with GC methods, more than 60 organic fluids are screened for medium-low temperature ORCs. The results indicate that the GC methods can estimate thermal properties with acceptable accuracy (mean relative errors are 4.45%-11.50%);the precision, however, is low because the relative errors can vary from less than 0.1% to 45.0%. By contrast, the GC-based estimation of thermal efficiency has better accuracy and precision. The relative errors in thermal efficiency have an arithmetic mean of about 2.9% and fall within the range of 0-24.0%. These findings suggest that the analytical equations provide not only a direct way of estimating thermal efficiency but an accurate and precise approach to evaluating working fluids and guiding computer-aided molecular design of new fluids for ORCs using GC methods.
文摘离子液体(ILs)具有高稳定性、溶解性能好、可设计性、易回收等优点,尤其因高CO_(2)溶解度在碳捕集方面显示了巨大潜力。但由于ILs种类繁多且价格昂贵,依靠实验研究耗时费力,因此构建ILs体系的热力学预测模型至关重要。UNIFAC模型在ILs气体分离工艺设计与优化领域具有重要的理论价值和工程应用意义,基于此,本研究构建了应用于ILs-CO_(2)体系活度系数预测的UNIFAC模型。本文系统收集了CO_(2)在ILs中的溶解度实验数据,并结合相平衡计算出活度系数,建立了ILs-CO_(2)体系活度系数数据库。采用COSMO方法和van der Waals规则分别获得了UNIFAC模型中基团的重要参数(R_(k)和Q_(k))。基于实验值,拟合了UNIFAC相互作用参数。通过平均相对误差(AARD),比较了两种方法建立的UNIFAC模型的预测效果。结果表明:通过COSMO方法(AARD=7.68%)建立的UNIFAC模型对ILs-CO_(2)体系的活度系数预测误差比van der Waals方法(AARD=12.57%)降低了4.89个百分点。并在此基础上建立了ILs-CO_(2)体系UNIFAC模型,获得了近100对基团的相互作用参数数据库。由于UNIFAC模型的基团贡献特点,本工作建立的UNIFAC模型可预测数据库中包含的基团组成的新型ILs与CO_(2)体系的活度系数,从而为后续ILs法气体吸收的分子设计奠定了扎实基础。
文摘There are limited Vapor-Liquid Equilibrium（VLE） data in cluding N-formylmorpholine（NFM） for the design of the extractive distil lation process using NFM as solvent.The new interaction parameters of UNIFAC mo del were fitted with experimental data between CH2,ACH and NFM which was rega rded as a main group.Comparison of the prediction results of VLE data and infin ite dilution activity coefficients with other published methods of group divisio n for NFM, indicated more satisfying results with the interaction parameters of this paper. The four methods of group division for NFM were discussed based on the group division for ring molecule and group charge distribution. The group c harge distribution at the minimum energy state was calculated by the AM1 method in Chem3D Pro. The good theoretical basis was presented for the group division of NFM.
