The steady multi component vapor flows between two closed surfaces of evaporation and condensation are investigated numerically by the nonlinear Bhatnagar Gross Krook equation. The mathematical model will make it poss...The steady multi component vapor flows between two closed surfaces of evaporation and condensation are investigated numerically by the nonlinear Bhatnagar Gross Krook equation. The mathematical model will make it possible to determine the profiles of the process variables between two surfaces of evaporation and condensation if the conditions of evaporation and condensation surfaces are taken into consideration. It is used to simulate the vapor behaviors of the pure dibutylphthalate and the ethylhexyl phthalate ethylhexyl sebacate mixture. The effects of the liquid composition of the evaporation surface, the evaporation temperature, the condensation temperature and the distance between evaporation and condensation surfaces on the evaporation efficiency and separation factor are discussed.展开更多
Traditional distillation(TD)is generally an energy-intensive and inefficient process for separation and purification of liquids in chemical industries.Herein,we developed an interface-enhanced distillation(IED)by empl...Traditional distillation(TD)is generally an energy-intensive and inefficient process for separation and purification of liquids in chemical industries.Herein,we developed an interface-enhanced distillation(IED)by employing a well-arranged membrane of reduced graphene oxide(rGO)sheet arrays embedded with silicon dioxide nanofibres(rGO/SiO2)as the evaporation intermediate layer on the liquid surface.This IED enlarges the evaporation surfaces and weakens the intermolecular forces on the liquid/solid/gas interfaces,realizing the fast and even low temperature fraction collection with less energy consumption.The IED delivers evaporation rates 200%–300%times that of TD,meanwhile having an energy saving of 40%–60%and a time saving of 50%–70%for diverse liquid feeds.In atmospheric IED manner,high boiling point and perishable organics can be collected with high quality at a temperature lower than their boiling points.This IED provides an innovative strategy for highly efficient distillation in chemical industries.展开更多
Using molecular dynamics simulation, we compared evaporation behavior of a tiny amount of water molecules adsorbed on solid surfaces with different dipole lengths, including surface dipole lengths of 1 fold, 2 folds, ...Using molecular dynamics simulation, we compared evaporation behavior of a tiny amount of water molecules adsorbed on solid surfaces with different dipole lengths, including surface dipole lengths of 1 fold, 2 folds, 4 folds, 6 folds and 8 folds of 0.14 nm and different charges from 0.1e to 0.9e. Surfaces with short dipole lengths (1-fold system) can always maintain hydrophobic character and the evaporation speeds are not influenced, whether the surface charges are enhanced or weakened; but when surface dipole lengths get to 8 folds, surfaces become more hydrophilic as the surface charge increases, and the evaporation speeds increase gradually and monotonically. By tuning dipole lengths from 1-fold to 8-fold systems, we confirmed non-monotonic variation of the evaporation flux (first increases, then decreases) in 4 fold system with charges (0.1e-0.7e), reported in our previous paper [S. Wang, et al., J. Phys. Chem. B 116 (2012) 13863], and also show the process from the enhancement of this unexpected non-monotonic variation to its vanishment with surface dipole lengths increasing. Herein, we demonstrated two key factors to influence the evaporation flux of a tiny amount of water molecules adsorbed on solid surfaces: the exposed surficial area of water aggregation from where the water molecules can evaporate directly and the attraction potential from the substrate hindering the evaporation. In addition, more interestingly, we showed extra steric effect of surface dipoles on further increase of evaporation flux for 2-folds, 4-folds, 6-folds and 8-folds systems with charges around larger than 0.7e. (The steric effect is first reported by parts of our authors [C. Wang, et al., Sci. Rep. 2 (2012) 358]). This study presents a complete physical picture of the influence of surface dipole lengths on the evaporation behavior of the adsorbed tiny amount of water.展开更多
文摘The steady multi component vapor flows between two closed surfaces of evaporation and condensation are investigated numerically by the nonlinear Bhatnagar Gross Krook equation. The mathematical model will make it possible to determine the profiles of the process variables between two surfaces of evaporation and condensation if the conditions of evaporation and condensation surfaces are taken into consideration. It is used to simulate the vapor behaviors of the pure dibutylphthalate and the ethylhexyl phthalate ethylhexyl sebacate mixture. The effects of the liquid composition of the evaporation surface, the evaporation temperature, the condensation temperature and the distance between evaporation and condensation surfaces on the evaporation efficiency and separation factor are discussed.
基金This work was supported by the Ministry of Science and Technology of China(2016YFA0200200 and 2017YFB1104300)the National Science Foundation of China(51673026,51433005 and 21805160)+1 种基金NSFC-MAECI(51861135202),NSFC-STINT(21911530143)and Beijing Natural Science Foundation(2152028).Computations were carried out on the“Explorer 100”cluster system of Tsinghua National Laboratory for Information Science and Technology.
文摘Traditional distillation(TD)is generally an energy-intensive and inefficient process for separation and purification of liquids in chemical industries.Herein,we developed an interface-enhanced distillation(IED)by employing a well-arranged membrane of reduced graphene oxide(rGO)sheet arrays embedded with silicon dioxide nanofibres(rGO/SiO2)as the evaporation intermediate layer on the liquid surface.This IED enlarges the evaporation surfaces and weakens the intermolecular forces on the liquid/solid/gas interfaces,realizing the fast and even low temperature fraction collection with less energy consumption.The IED delivers evaporation rates 200%–300%times that of TD,meanwhile having an energy saving of 40%–60%and a time saving of 50%–70%for diverse liquid feeds.In atmospheric IED manner,high boiling point and perishable organics can be collected with high quality at a temperature lower than their boiling points.This IED provides an innovative strategy for highly efficient distillation in chemical industries.
基金Supported by National Natural Science Foundation of China under Grant Nos.11175230 and 11105088National Program on Key Basic Research Project under Grant No.2012CB932400Shanghai Supercomputer Center of China and Shanghai University Supercomputer (ZQ3000&4000)
文摘Using molecular dynamics simulation, we compared evaporation behavior of a tiny amount of water molecules adsorbed on solid surfaces with different dipole lengths, including surface dipole lengths of 1 fold, 2 folds, 4 folds, 6 folds and 8 folds of 0.14 nm and different charges from 0.1e to 0.9e. Surfaces with short dipole lengths (1-fold system) can always maintain hydrophobic character and the evaporation speeds are not influenced, whether the surface charges are enhanced or weakened; but when surface dipole lengths get to 8 folds, surfaces become more hydrophilic as the surface charge increases, and the evaporation speeds increase gradually and monotonically. By tuning dipole lengths from 1-fold to 8-fold systems, we confirmed non-monotonic variation of the evaporation flux (first increases, then decreases) in 4 fold system with charges (0.1e-0.7e), reported in our previous paper [S. Wang, et al., J. Phys. Chem. B 116 (2012) 13863], and also show the process from the enhancement of this unexpected non-monotonic variation to its vanishment with surface dipole lengths increasing. Herein, we demonstrated two key factors to influence the evaporation flux of a tiny amount of water molecules adsorbed on solid surfaces: the exposed surficial area of water aggregation from where the water molecules can evaporate directly and the attraction potential from the substrate hindering the evaporation. In addition, more interestingly, we showed extra steric effect of surface dipoles on further increase of evaporation flux for 2-folds, 4-folds, 6-folds and 8-folds systems with charges around larger than 0.7e. (The steric effect is first reported by parts of our authors [C. Wang, et al., Sci. Rep. 2 (2012) 358]). This study presents a complete physical picture of the influence of surface dipole lengths on the evaporation behavior of the adsorbed tiny amount of water.
