Soret-‘shifted’ dew-point temperatures for surfaces exposed to hydrocarbon vapors dilute in compressed nitrogen

Soret-driven species transport causes concentration non-uniformities in the immediate vicinity of ‘cold’ surfaces immersed in undersaturated vapor-containing streams. These concentration non-uniformities, in turn, alter corresponding condensation onset temperatures, often by as much as 30 K (i.e., ca. 3%) in previously studied, near-atmospheric pressure combustion systems [see, e.g., Rosner, D.E. and Nagarajan, R., 1985. Chemical Engineering Science 40 (2), 177]. Because high-pressures often cause remarkable increases in the relevant binary Soret factor, α_T,12, we investigate here the importance of these vapor phase ‘transport’ effects for ‘compressed’ N₂ streams containing dilute quantities of an alkane: C₁₂H₂₆ (n-dodecane) or C₈H₁₈ (n-octane). We invoke the virial equation of state (VES) to predict gas phase non-ideality, and its appreciable effect on previously available ideal gas Soret factors. Our illustrative numerical results, valid for, say, nominally 1000 K N₂ streams up to pressures of over 100 atm, reveal that high-pressure Soret ‘shifts’ in T_dp can amount to ca. 80%, even at surface temperatures above the equilibrium freezing points of these condensates. We conclude that these high-pressure vapor phase transport phenomena will not only influence the interpretation of such hot gas/‘cold’ surface ‘dew-point’ measurements, they will significantly raise the temperatures at which containment or immersed surfaces must be maintained to avoid the ravages of corrosive or insulating inorganic condensates [Rosner, D.E., Chen, B.K., Fryburg, G.C., Kohl, F.J., 1979. Combustion Science and Technology 20, 87; Rosner, D.E., 1988a. Invited paper, Benjamin G. Levich Memorial Issue of Journal of Physico-Chemical Hydrodynamics 10 (5/6), 663]. In principle, the present theory could itself be used to study the pressure dependence of the binary Soret factor—at least for systems with well-characterized saturation vapor pressures.     

气体和气体混合物的单参数状态方程

1 INTRODUCTIONThere are many equations of state that can be appliedto calculate pVT and thermodynamic properties forfluids.The simplest equation of state for gas is thefamous virial equations with the second coefficient B     

Setting Up a Databank on the Properties of Substances and Materials: A Task Undertaken by the State Reference Data Service

Research results are reported for a databank on the thermophysical properties of substances and materials, which covers researches in the Soviet Union and Russia between 1950 and 2000. An archive of 3475 documents has been set up, which provides bibliographic information on the publications containing the original experimental data and which has been implemented in the Lotus Notes environment. The database organization and retrieval in it are considered.     

钼金属加工系统烟气治理设施改造

简要介绍了钼金属加工系统烟气的性质、扩散机理及治理设施的改造     

Adsorption of Cd(II), Pb(II), and Ag(I) in aqueous solution on hollow chitosan microspheres

Cross‐linked chitosans synthesized by the inverse emulsion cross‐link method were used to investigate adsorption of three metal ions [Cd(II), Pb(II), and Ag(I)] in an aqueous solution. The chitosan microsphere, was characterized by FTIR and SEM, and adsorption of Cd(II), Pb(II), and Ag(I) ions onto a cross‐linked chitosan was examined through analysis of pH, agitation time, temperature, and initial concentration of the metal. The order of adsorption capacity for the three metal ions was Cd²⁺ > Pb²⁺ > Ag⁺. This method showed that adsorption of the three metal ions in an aqueous solution followed the monolayer coverage of the adsorbents through physical adsorption phenomena and coordination because the amino (? NH₂) and/or hydroxy (? OH) groups on chitosan chains serve as coordination sites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

汽车三效催化剂失活研究的进展

随着对汽车三效催化剂耐久性能要求的日益提高,因而对催化剂抗老化性能提出了更高的挑战,本文主要介绍了汽车三效催化剂失活的主要类型,包括:机械失活、化学失活及热失活。阐明了目前汽车三效催化剂所面临的主要的失活问题就是涂层基体γ-Al2O3烧结和贵金属的老化,同时论述了目前对γ-Al2O3和贵金属的主要改性方法,指出开发新型的耐高温稳定的涂层材料是目前所要研究的重点。     

Integrated multi‐echelon supply chain design with inventories under uncertainty: MINLP models,computational strategies

We address in this article a problem that is of significance to the chemical industry, namely, the optimal design of a multi‐echelon supply chain and the associated inventory systems in the presence of uncertain customer demands. By using the guaranteed service approach to model the multi‐echelon stochastic inventory system, we develop an optimization model to simultaneously determine the transportation, inventory, and network structure of a multi‐echelon supply chain. The model is an MINLP with a nonconvex objective function including bilinear, trilinear, and square root terms. By exploiting the properties of the basic model, we reformulate this problem as a separable concave minimization program. A spatial decomposition algorithm based on the integration of Lagrangean relaxation and piecewise linear approximation is proposed to obtain near global optimal solutions with reasonable computational expense. Examples for specialty chemicals and industrial gas supply chains with up to 15 plants, 100 potential distribution centers, and 200 markets are presented. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

稀四氟化碳气体混合物传递性质的确定(英文)

In our previous work, we calculated transport properties of pure gaseous polyatomic carbon tetrafluoride (CF4) and five equimolar binary gas mixtures of CF4 with noble gases through inversion technique. The present work is a continuation of our studies on determining the transport properties of binary gas mixtures CF4 with some gases including three diatomic molecules CO, N2, and O2, a linear polyatomic CO2, and two non-linear polyatomic molecules SF6 and CH4. The Chapman-Enskog and Vesovic-Wakeham methods as well as inversion procedure are used to determine the viscosities, diffusivities, and thermal conductivities, which deviates from the literature values within 1%, 4%, and 5%, respectively.     

Insights on global warming

The global temperature increase over the last century and a half (～ 0.8°C), and the last three decades in particular, is well outside of that which can be attributed to natural climate fluctuations. The increase of atmospheric CO₂ over this period has been conclusively demonstrated to be a result largely of fossil fuel burning. The global mean temperature change that results in response to a sustained perturbation of the Earth's energy balance after a time sufficiently long for both the atmosphere and oceans to come to thermal equilibrium is termed the Earth's climate sensitivity. The purely radiative (blackbody) warming from a doubling of CO₂ from its preindustrial level of 280 parts‐per‐million (ppm) to 560 ppm is ～ 1.2°C; the actual warming that would result is considerably larger owing to amplification by climate feedbacks, including that owing to water vapor. Increases in greenhouse gas (GHG) levels are estimated to have contributed about +3.0 W m^?2 perturbation (radiative forcing) to the Earth's energy balance. Particles (aerosols), on the whole, exert a cooling effect on climate, with a total forcing estimated by the Intergovernmental Panel on Climate Change (2007)¹ as ?1.2 W m^?2, a value that is subject to considerable uncertainty. If the actual magnitude of aerosol forcing is close to the low end of its estimated uncertainty range, then it offsets a considerably smaller fraction of the GHG forcing and the total net forcing is at the high end of its range, ～ 2.4 W m^?2; at the other extreme, if the actual aerosol cooling is at the high end of its range, then aerosol forcing is currently offsetting a major fraction of GHG forcing, and the total net forcing is only ～ 0.6 W m^?2. To explain the actual global increase in temperature of ～ 0.8°C, these two extremes have major implications in terms of the Earth's climate sensitivity. Climate sensitivity is determined by the strength of feedbacks, of which cloud feedback is the most uncertain. That the Earth has warmed and that GHGs are responsible is unequivocal; the Earth's climate sensitivity and the effect of aerosols complicate answers to the question: how much warming and how soon? © 2011 American Institute of Chemical Engineers AIChE J, 2011