Rate constants for the homogeneous gas-phase Al/HCl combustion chemistry

Swihart, Mark T.

doi:10.1016/s0010-2180(02)00426-1

Cited by 36 publications

(18 citation statements)

References 17 publications

(26 reference statements)

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“…with rates for the forward reactions taken from McClean et al (1993); Sharipov et al (2011), andSwihart et al (2003), respectively. Silicon, like aluminum, is present in molecular compounds at the lower boundary with SiO the most abundant species.…”

Section: Other Atomsmentioning

confidence: 99%

Electron Densities and Alkali Atoms in Exoplanet Atmospheres

Lavvas

Koskinen

Yelle

2014

ApJ

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We describe a detailed study on the properties of alkali atoms in extrasolar giant planets, and specifically focus on their role in generating the atmospheric free electron densities, as well as their impact on the transit depth observations. We focus our study on the case of HD 209458 b, and we show that photoionization produces a large electron density in the middle atmosphere that is about two orders of magnitude larger than the density anticipated from thermal ionization. Our purely photochemical calculations though result in a much larger transit depth for K than observed for this planet. This result does not change even if the roles of molecular chemistry and excited state chemistry are considered for the alkali atoms. In contrast, the model results for the case of exoplanet XO-2 b are in good agreement with the available observations. Given these results we discuss other possible scenarios, such as changes in the elemental abundances, changes in the temperature profiles, and the possible presence of clouds, which could potentially explain the observed HD 209458 b alkali properties. We find that most of these scenarios can not explain the observations, with the exception of a heterogeneous source (i.e. clouds or aerosols) under specific conditions, but we also note the discrepancies among the available observations. Subject headings: planetary systems planets and satellites: atmospheres, composition, individual (HD 209458 b, XO-2 b)

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Section: Other Atomsmentioning

confidence: 99%

Electron Densities and Alkali Atoms in Exoplanet Atmospheres

Lavvas

Koskinen

Yelle

2014

ApJ

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“…Three oxidizers, O 2 , H 2 O, and CO 2 , are considered in this work. The corresponding reaction mechanisms are taken from refs ( 13 )( 62 ), and ( 63 ). From Figure 8 , we can see that the production of aluminum oxide directly comes from Al 2 O 2 , AlO, and AlO 2 .…”

Section: Resultsmentioning

confidence: 99%

On Modeling the Combustion of a Single Micron-Sized Aluminum Particle with the Effect of Oxide Cap

2021

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The formation of oxide cap, which results from the condensation of gaseous aluminum oxide, makes a non-negligible impact on the combustion process of micron-sized aluminum particles, but its growth and effect are still unknown. Also, the transition of combustion modes during the combustion process, which affects the growth rate of the oxide cap, needs to be explored. Therefore, a detailed combustion model of a single micron-sized aluminum particle is developed to predict the transition of combustion modes and the effect of the oxide cap. This combustion model consists of a vapor-phase kinetic model and a particle model coupled by the Strang splitting algorithm. The predicted ignition delay and combustion times are compared with experimental data to validate the combustion model. Three combustion modes including vapor-phase, transitional, and surface combustions are considered in this combustion model. We find that the two modes coexist for particles between 100 and 200 μm when the ambient temperature and pressure are 2500 K and 1 atm, respectively. A higher ambient temperature extends the transition of combustion mode toward smaller sizes. An oxide cap model considering surface free energy is proposed to study the growth and effect of the oxide cap on the combustion process of micron-sized aluminum particles. We find that the formation of oxide cap limits the evaporation rate of aluminum directly due to the reduced active surface area. The oxide cap stabilizes the evolution of particle temperature and determines the burning time. The predicted burning time is reduced by a factor of 2 at least considering the growth of oxide cap.

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“…2Al + 6H 2 O + 2NaOH → 2Na + + 2Al(OH) 4 − + 3H 2 ↑ with −r Al = kC Al 2 C H 2 O 6 C NaOH 2 in base [12], 2Al + 6H 2 O → 2Al(OH) 3 ↓ + 3H 2 ↑ with −r Al = kC Al 2 C H 2 O 6 in neutral water [6], and 2Al + 3H 2 O + 3HCl → AlCl 3 ↓ + Al(OH) 3 ↓ + 3H 2 ↑ with −r Al = kC Al 2 C H 2 O 3 C HCl 3 in acid [38]. In these expressions, −r Al and k denoted the reaction rate of ANP and the rate constant, respectively.…”

Section: Effect Of Ph Value On the Thermal Properties Of Anpmentioning

confidence: 99%