SET Proceedings 2978-4387 Caravel Press 10.65582/set.2010.205 2010.205 The Impact of n-hexanol on the Liquid-Vapor Interface of an Electrolyte Solution ZhuBeibei parabola1981@yahoo.com.cn GaoHongtao GeGuangtao Marine Engineering College, Dalian Maritime University, Dalian, People's Republic of China Zhejiang GongShang University, Hangzhou, People's Republic of China 24082010 9 978-1-995850-04-7 1 10 24 August 2010 © 2010 Copyright WSSET 2010

Molecular dynamics simulation methods are used to investigate the impact of n-hexanol, a sort of organic surfactant, on the absorption process of water vapour into aqueous LiBr solution. Various amount of n-hexanol were simulated at room temperature. Density distribution along the normal direction of the interface, the radial distribution functions of ions and hydroxyl group of n-hexanol and orientational order parameter of n-hexanol are calculated to study the micro-configuration of the liquid-vapour interface of lithium bromide aqueous solution with n-hexanol. The simulation results demonstrate that n-hexanol molecules are inclined to aggregate at the interface with preferred orientation. The alkyl groups of n-hexanol are close to stay upright when the number of n-hexanol is more, meanwhile, this orientational ordering became significant with the increase of the amount of n-hexanol. Ions are negatively adsorbed at the interface and the interaction of ions and hydroxyl group exists. The dynamic process of water vapour absorption into lithium bromide aqueous solution with or without n-hexanol is investigated by molecular dynamics simulation under non-equilibrium condition. The simulation results demonstrate that in comparison to the lithium bromide aqueous solution without n-hexanol, the lithium bromide aqueous solution with n-hexanol can absorb more water molecules obviously for 100ps, which conforms to the experimental tendency.

 surfactant lithium bromide aqueous solution molecular simulation absorption 24 to 27 August 2010 9th International Conference on Sustainable Energy Technologies SET2010 9 Shanghai, China Srikhirin P, Aphornratana S, Chungpaibulpatana S. A review of absorption refrigeration technologies. Renewable and Sustainable Energy reviews, 2001, 5, 343-372. Kilic M, Kaynakli O. Second law-based thermodynamic analysis of water-lithium bromide absorption refrigeration system. Energy, 2007, 32, 1505–1512. Granryd E, Palm B. Refrigerating engineering. Stockholm Royal Institute of Technology, 2005. Miller W A, Keyhani M. The experimental analysis of local heat and mass transfer data for vertical falling film absorption. International Mechanical Engineering Congress and Exposition, Nashville, TN (US), 1999. Glebov D, Setterwall F. Experimental study of heat transfer additive influence on the absorption chiller performance. International Journal of Refrigeration, 2002, 25, 538-545. Kulankara S, Herold K E. Surface tension of aqueous lithium bromide with heat/mass transfer enhancement additives: the effect of additive vapor transport. International Journal of Refrigeration, 2002, 25, 383-389. Kulankara S. Effect of enhancement additives on the absorption of water vapor by aqueous lithium bromide. PhD Dissertation, University of Maryland, 1999. Bourne J R, Eisberg K V. Maintaining the effectiveness of an additive in absorption refrigeration systems. US Patent # 3,276,219, 1966. Albertson C E, Park V, Krueger R H. Heat transfer additives for absorption solutions. US Patent #3,580,759, 1971. Chi C W, Macriss R A, Rush W F. Secondary alcohol additives of LiBr-water absorption refrigeration system. US Patent #3,609,087, 1971. Modahl R, Lynch, P J. Absorption heat exchange systems, methods and absorbent compositions. US Patent #3,783,631, 1974. Rush W F, Wurm J, Perez-Blanco H, Sheehan D S. On uses and effects of additives for absorption enhancement. Munich Discussion Meeting 94. Kashiwagi T, Kurosaki Y, Shishido H. Enhancement of vapor absorption into a solution using the Marangoni effect. Trans JSME, 1985(B), 51, 1002-1009. Hozawa M, Inoue M, Sao J et al. Marangoni convection during steam absorption into aqueous LiBr solution with surfactant. J Chemical Engineering of Japan 1991, 24(2), 209-214. Kulankara S, Verma S, Herold K E. Theory of heat/mass transfer additives in absorption chillers. Proceedings of IMECE: International Mechanical Engineering Conference and Exhibit. November 1999, Nashville TN. Yuan Z, Herold K E. Surface tension of pure water and aqueous lithium bromide with 2-ethyl-hexanol. Applied Thermal Engineering, 2001, 21, 881-897. Daiguji H, Hihara E, Saito T. Mechanism of absorption enhancement by surfactant. Int J Heat Mass transfer, 1997, 40(8), 1743–1752. Qiao R, Yuan Z, Herold K E. Surface tension driven film flow due to condensation with a vapor brone surfactant. International Mechanical Engineering Congress & Exhibition 5-10 November 2000, Orlando Florida, 169-174. Rie D H, Kashiwagi T. Computer simulation of vapor-absorption enhancement into H2O/LiBr absorbent by Marangoni convection. JSME International Journal, Series 2: Fluids Engineering, Heat Transfer, Power, Combustion, Thermophysical Properties, 1991, 34(3), 355-361. Daiguji H, Molecular dynamics study of n-alcohols adsorbed on an aqueous electrolyte solution, J Chem Phys, 2001, 115, 4, 1538-1549. Daiguji H, Hihara E. Molecular dynamics study of water vapor absorption into an aqueous electrolyte solution. Microscale Thermophysical Engineering, 1999, 3, 151-165. Hess B, Kutzner C, Spoel D, et al. GROMACS 4: Algorithms for highly efficient, load-balanced, and scalable molecular simulation. J Chem Theory Comput, 2008, 4(3), 435-447. Jorgensen W L, Maxwell D S, Tirado-Rives J. Development and testing of the OPLS All-Atom force field on conformational energetics and properties of organic liquids. J Am Chem Soc, 1996, 118, 11225-11236. Damm W, Frontera A, Tirado-Rives J, Jorgensen W L. OPLS All-Atom force field for carbohydrates. J Comput Chem, 1997, 18(16), 1955-1970. McDonald N A, Jorgensen W L. Development of an All-Atom force field for heterocycles. properties of liquid pyrrole, Furan, Diazoles, and Oxazoles. J Phys Chem B, 1998, 102, 8049-8059. Rizzo R C, Jorgensen W L. OPLS all-atom model for amines: resolution of the Amine hydration problem. J Am Chem Soc, 1999, 121, 4827-4836. Watkins E K, Jorgensen W L. Perfluoroalkanes:conformational analysis and liquid-state properties from ab initio and monte carlo calculations. J Phys Chem A, 2001, 105, 4118-4125. Price M L P, Ostrovsky D, Jorgensen W L. Gas-phase and liquid-state properties of esters, nitriles, and nitro compounds with the OPLS-AA force field. J Comput Chem, 2001, 22(13), 1340-1352. Aqvist J. Ion-water interaction potentials derived from free energy perturbation simulations. J Phys Chem, 1990, 94, 8021-8024. Lybrand T P, Ghosh I, McCammon J A. Hydration of chloride and bromide anions: determination of relative free energy by computer simulation. J Am Chem Soc, 1985, 107 (25), 7793-7794. Nose S. A molecular dynamics method for simulations in the canonical ensemble. Mol Phys, 1984, 52(2), 255-268. Hoover W G. Canonical dynamics: equilibrium phase-space distributions. Phys Rev A, 1985, 31(3), 1695-1697. Parrinello M, Rahman A. Polymorphic transitions in single crystals: a new molecular dynamics method. J Appl Phys, 1981, 52(12), 7182-7190. Nose S, Klein M L. Constant pressure molecular dynamics for molecular systems. Mol Phys, 1983, 50(5), 1055-1076. van Gunsteren W F, Berendsen H J C. A leap-frog algorithm for stochastic dynamics. Mol Sim, 1988, 1, 173-185. Miyamoto S, Kollman P A. SETTLE: an analytical version of the SHAKE and RATTLE algorithm for rigid water models[J]. J Comput Chem, 1992, 13(8), 952-962. Hess B, Bekker H, Berendsen H J C, Fraaije J G E M. LINCS: A linear constraint solver for molecular simulations. J Comp Chem, 1997, 18, 1463-1472. Hess, B. P-lincs: A parallel linear constraint solver for molecular simulation. J Chem Theory Comp. 2007, 4, 116-122. Darden T, York D, Pedersen L Particle mesh Ewald: An N-log(N) method for Ewald sums in large systems. J Chem Phys, 1993, 98, 10089-10092. Essmann U, Perera L, Berkowitz M L, Darden T, Lee H, Pedersen L G. A smooth particle mesh ewald potential. J Chem Phys, 1665, 103, 8577-8592. Van der Waals J D. On the continuity of the gaseous and liquid states. Studies in Statistical Mechanics, 1988, 14, North Holland, Amsterdam. Harris J G. Liquid-vapor interfaces of alkane oligomers: structure and thermodynamics from molecular dynamics simulations of chemically realistic models. J Phys Chem, 1992, 96 (12), 5077-5086. Chen B, Siepmann J I, Klein M L. Vapor-liquid interfacial properties of mutually saturated water/1-butanol solutions. J Am Chem Soc, 2002, 124, 12232-12237. Petersen P B, Saykally R J. On the nature of ions at the liquid water surface. Annu Rev Phys Chem, 2006, 57, 333-364. Chang T M, Dang L X. Liquid–vapor interface of methanol-water mixtures: a molecular dynamics study. J Phys Chem B, 2005, 109, 5759-5756. Krisch M J, D’Auria R, Brown M A, Tobias D J, Hemminger J C. The effect of an organic surfactant on the liquid-vapor interface of an electrolyte solution. J Phys Chem C, 2007, 111, 13497-13509. Ziegler F, Grossman G. Heat-transfer enhancement by additives. Int J Refrig, 1996, 19(5), 301-309.