Clathrate equilibrium data for CO 2 +N 2 mixtures with TBAB, TBAF, CP, TBAB+CP, TBAF+CP promoters

International audienceCarbon Dioxide capture and sequestration (CCS) is nowadays an important area of research for alleviating CO 2 emissions worldwide. According to [1], CO 2 is globally the largest pollutant to which the global warming is attributed. Consequently, hydrates can become of great importance as they form the basis for a new technology that concerns CO 2 capture from flue gases (hydrate crystallization). In this work hydrate equilibrium data measured at the Centre Thermodynamic of Processes in MINES ParisTech (France) are presented as part of a collaborative project funded by the Danish Technical Research Council. More particularly, in this study experimental results for hydrate dissociation with several promoters are presented. The isochoric method is used to determine the gas hydrate dissociation points. Different CO 2 +N 2 gas mixtures were used with presence of promoters such as tetra-butylammonium bromide (TBAB), tetra-butylammonium fluoride (TBAF), cyclopentane (CP) and mixtures of TBAB and TBAF with CP. The combination of TBA halides with CP was inspired by [2] as it came out synergetic effect that enhances promotion between TBAB (5% w/w) and CP (5% v/v). The results have shown synergetic effect for 20% w/w TBAB+CP (5% v/v) and partly (>30 bar) for 5% w/w TBAF+CP (5% v/v). Concerning experiments with pure promoter, there is excellent consistency between our results and literature for different gas mixtures and promoter concentrations. Moreover, they exhibit very good agreement with existing literature

Predicting enhanced absorption of light gases in polyethylene using simplified PC-SAFT and SAFT-VR

International audienceAbsorption of light gases in polyethylene (PE) is studied using two versions of the Statistical Associating Fluid Theory (SAFT): SAFT for chain molecules with attractive potentials of variable range (VR) and simplified perturbed-chain (PC) SAFT. Emphasis is placed on the light gases typically present during ethylene polymerisation in the gas-phase reactor (GPR) process. The two approaches are validated using experimental binary-mixture data for gas absorbed in PE, and predictions are made for mixtures of more components. For most cases studied both SAFT versions perform equally well. For the case of ternary mixtures of two gases with PE, it is predicted that the less-volatile of the two gases acts to enhance the absorption of the more-volatile gas, while the more-volatile gas inhibits the absorption of the less-volatile gas. This general behaviour is also predicted in mixtures containing more gases, such as typical reactor mixtures. The magnitude of the effect may vary considerably, depending on the relative proximity of the gas-mixture saturation pressure to the reactor pressure; for example it is predicted that the absorption of ethylene may be approximately doubled if diluent gases, propane or nitrogen, are partially or completely replaced by less-volatile butane or pentane for a reactor pressure similar to 2 MPa. In the case of a co-polymerisation reaction, it is predicted that increases in absorption of both co-monomers may be obtained in roughly equal proportion. Our findings cast light on the so-called co-monomer effect, in which substantial increases in the rate of ethylene polymerisation are observed in the presence of hexene co-monomer, while suggesting that the effect is more general and not restricted to co-monomer. For example, similar rate increases may be expected in the presence of, e.g., pentane instead of hexene, but without the change in the branch structure of the produced polymer that is inevitable when the amount of co-monomer is increased

On the Degree of Team Cooperation in CD Grammar Systems.

In this paper, we introduce a dynamical complexity measure, namely the degree of team cooperation, in the aim of investigating "how much" the components of a grammar system cooperate when forming a team in the process of generating terminal words. We present several results which strongly suggest that this measure is trivial in the sense that the degree of team cooperation of any language is bounded by a constant. Finally, we prove that the degree of team cooperation of a given cooperating/distributed grammar system cannot be algorithmically computed and discuss a decision problem

Landau-Ginzburg method applied to finite fermion systems: Pairing in Nuclei

Given the spectrum of a Hamiltonian, a methodology is developed which employs the Landau-Ginsburg method for characterizing phase transitions in infinite systems to identify phase transition remnants in finite fermion systems. As a first application of our appproach we discuss pairing in finite nuclei.Comment: 14 pages, 4 figure

The influence of parathyroid hormone upon bone formation in xenopus laevis

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