798 research outputs found
Mass transfer characteristics in structured packing for CO2 emission reduction processes
Acid gas treating and CO2 capture from flue gas by absorption have gained wide importance over the past few decades. With the implementation of more stringent environmental regulations and the awareness of the greenhouse effect, the need for efficient removal of acid gases such as CO2 (carbon dioxide) has increased significantly. Therefore, additional effort for research in this field is inevitable. For flue gas processes the ratio of absorption solvent to gas throughput is very different compared to acid gas treating processes owing to the atmospheric pressures and the dilution effect of combustion air. Moreover, in flue gas applications pressure drop is a very important process parameter. Packing types are required that allow for low pressure drop in combination with high interfacial areas at low liquid loading per square meter. The determination of interfacial areas in gas-liquid contactors by means of the chemical method (Danckwerts, P. V. Gas-liquid reactions; McGraw-Hill: London, 1970) has been very frequently applied. Unfortunately, many of the model systems proposed in the literature are reversible and therefore this condition possibly is not met. Versteeg et al. (Versteeg, G. F.; Kuipers, J. A. M.; Beckum, F. P. H.; van Swaaij, W. P. M. Chem. Eng. Sci. 1989, 44, 2292) have demonstrated that for reversible reactions the conditions for the determination of the interfacial area by means of the chemical method are much more severe. In a study by Raynal et al. (Raynal, L.; Ballaguet, J. P.; Berrere-Tricca, C. Chem. Eng. Sci. 2004, 59, 5395), it has been shown that there is a dependency of the interfacial area on the packing height. Unfortunately, most model systems used, e.g., CO2-caustic soda (as used by Raynal et al.), are much more complex and consist of (a set of) reversible reaction(s). The natures of these systems make the conditions at which the interfacial area can be determined much more severe and put more limitations on the process conditions and experimental equipment than a priori can be expected. Therefore, an extended absorption model is required to determine the conditions at which the interfacial area can be measured without detailed knowledge of the values of the liquid-side mass transfer coefficient, k1, beforehand.
The character of Vermont : twentieth-anniversary reflections
Occasional paper (University of Vermont. Center for Research on Vermont) ; no. 19.
pt. 1. The character of Vermont : then and now / Michael Sherman and Jennie Versteeg -- pt. 2. Vermont research and the center for research on Vermont / Samuel B. Hand, Paul Gillies
Dissociation constants and thermodynamic properties of amino acids used in CO2 absorption from (293 to 353) K
The second dissociation constants of the amino acids βalanine, taurine, sarcosine, 6-aminohexanoic acid, DL-methionine, glycine, L-phenylalanine, and L-proline and the third dissociation constants of L-glutamic acid and L-aspartic acid have been determined from electromotive force measurements at temperatures from (293 to 353) K. Experimental results are reported and compared to literature values. Values of the standard state thermodynamic properties are derived from the experimental results and compared to the values of commercially available amines used as absorbents for CO 2 capture.
Pairing of charged particles in a quantum plasmoid
We study a quantum spherically symmetric object which is based on radial
plasma oscillations. Such a plasmoid is supposed to exist in a dense plasma
containing electrons, ions, and neutral particles. The method of creation and
annihilation operators is applied to quantize the motion of charged particles
in a self-consistent potential. We also study the effective interaction between
oscillating particles owing to the exchange of a virtual acoustic wave, which
is excited in the neutral component of plasma. It is shown that this
interaction can be attractive and result in the formation of ion pairs. We
discuss possible applications of this phenomenon in astrophysical and
terrestrial plasmas.Comment: 17 pages, no figures, two columns, LaTeX2e; paper was significantly
revised; title was changed; 16 new references were included; the discussion
on ion-acoustic waves was added to Sec. 2; Secs. 3 and 4 were shortened; a
more detailed discussion was added to Sec. 7; accepted for publication to
J.Phys.
How uncertainty enables non-classical dynamics
The uncertainty principle limits quantum states such that when one observable
takes predictable values there must be some other mutually unbiased observables
which take uniformly random values. We show that this restrictive condition
plays a positive role as the enabler of non-classical dynamics in an
interferometer. First we note that instantaneous action at a distance between
different paths of an interferometer should not be possible. We show that for
general probabilistic theories this heavily curtails the non-classical
dynamics. We prove that there is a trade-off with the uncertainty principle,
that allows theories to evade this restriction. On one extreme, non-classical
theories with maximal certainty have their non-classical dynamics absolutely
restricted to only the identity operation. On the other extreme, quantum theory
minimises certainty in return for maximal non-classical dynamics.Comment: 4 pages + 4 page technical supplement, 2 figure
Enhanced CH absorption within Jupiter's southern auroral oval from Juno UVS observations
Reflected sunlight observations from the Ultraviolet Spectrograph (UVS) on
the Juno spacecraft were used to study the distribution of acetylene
(CH) at Jupiter's south pole. We find that the shape of the CH
absorption feature varies significantly across the polar region, and this can
be used to infer spatial variability in the CH abundance. There is a
localized region of enhanced CH absorption which coincides with the
location of Jupiter's southern polar aurora; the CH abundance poleward
of the auroral oval is a factor of 3 higher than adjacent quiescent,
non-auroral longitudes. This builds on previous infrared studies which found
enhanced CH abundances within the northern auroral oval. This suggests
that Jupiter's upper-atmosphere chemistry is being strongly influenced by the
influx of charged auroral particles and demonstrates the necessity of
developing ion-neutral photochemical models of Jupiter's polar regions.Comment: Accepted in JGR: Planet
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