Experimental and numerical study of ethanol oxidation in sub-critical water

Hirosaka, Kazuma; Koido, Kenji; Fukayama, Masato; Ouryoji, Kazuhiro; Hasegawa, Tatsuya

doi:10.1016/j.supflu.2007.09.009

Cited by 10 publications

(4 citation statements)

References 24 publications

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“…Though the concentration of ethanol in the experiment of Schanzenbächer et al [6] is 0.0472 mol%, which is much lower than that used for our calculation, i.e. 1.82 mol%, Hirosaka et al [9] demonstrated that a numerical simulation using the reaction rate obtained by the experiment with lower concentration of ethanol (0.131 mol%) well agreed with the experimental results obtained with higher concentration of ethanol (10.9 mol%).…”

Section: Reaction Ratesupporting

confidence: 72%

“…In the present study, the expression (19) by Schanzenbächer et al [6] is used as the reaction rate, because the reaction temperature in our study (above 350 • C) is closer to the temperature range used by Schanzenbächer et al than that of Hirosaka et al [9]. Though the concentration of ethanol in the experiment of Schanzenbächer et al [6] is 0.0472 mol%, which is much lower than that used for our calculation, i.e.…”

Section: Reaction Ratementioning

confidence: 61%

“…They showed an elementary reaction mechanism based on the work of Marinov [8] and proved that the formaldehyde was the primary stable organic intermediate. Hirosaka et al [4,9] have experimentally studied hydrothermal oxidation of ethanol under subcritical conditions. They confirmed that the temperature increased up to 120 • C owing to exothermic reaction and obtained the first-order reaction rate for ethanol oxidation.…”

Section: Introductionmentioning

confidence: 99%

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Numerical study on premixed hydrothermal combustion in tube reactor

Koido

Hirosaka

Kubo

et al. 2009

Combustion Theory and Modelling

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Premixed hydrothermal combustion of ethanol was numerically studied as a fundamental research to develop an energy conversion system utilising biomass and low quality oil. A simulation code available for oxidation of water solution mixture under sub/super critical conditions was developed. Lee-Kesler equation was selected as the equation of state. Chemical species of ethanol, oxygen, carbon dioxide and water, were considered as reactants and products of complete reaction. Mixing laws by Chung et al. and Wilke et al. were used for transport properties and that of Plöcker et al. was used for thermal properties and Lee-Kesler equation of state.Behaviours of ethanol oxidation under sub/super critical conditions were numerically simulated. For the reaction rate, we selected Schanzenbächer et al.'s expression obtained by the experiment under supercritical condition. Effects of preheat temperature, heat loss and flow velocity were examined by simulation. The differences of preheat temperatures led to the differences of temperature increase T around critical point because of the specific heat peak at the critical point. Larger flow velocity caused slower increase of ethanol conversion and temperature increase. Changes of reaction rate for different flow velocities showed that larger flow velocity caused thicker reaction zone and higher reaction peak than that for smaller one because of the fluid advection. From the calculation with different heat losses (different heat transfer rate coefficients α), twostep temperature decrease appeared for larger heat loss (α = 2.5 × 10 4 W·m −2 ·K −1 ) while monotonous temperature decrease appeared for smaller heat loss (α = 2.5×10 3 W·m −2 ·K −1 ).

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Section: Reaction Ratesupporting

confidence: 72%

Section: Reaction Ratementioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

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Numerical study on premixed hydrothermal combustion in tube reactor

Koido

Hirosaka

Kubo

et al. 2009

Combustion Theory and Modelling

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“…They reported the estimation of capacity for ethanol oxidation in subcritical water as a heat source. At the same time, Hirosaka (10) and Koido (11) have worked on the numerical simulation of the behaviour of reactive flow in the reactor. These studies have been implemented with a single step reaction rate of reactants considering decomposition of ethanol into acetic acid.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of Ethanol Oxidation in High-Pressure Steam

Koido

Hasegawa

2011

JTST

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Ethanol oxidation rate in high pressure steam at the pressure of 10 MPa in the temperature ranging from 430 to 490 °C was studied with the fuel equivalence ratio of 0.4. On the assumption that the reaction order is first order, the reaction rate parameters obtained in the experiments are 10 11.6 ± 0.4 s -1 for the pre-exponential factor and 166.5 ± 6.1 kJ·mol -1 for the activation energy. This ethanol oxidation rate in high-pressure steam was equivalent to that in supercritical water oxidation of ethanol. Liquid products were acetaldehyde and acetic acid and gas phase products were carbon monoxide, carbon dioxide, methane and ethane. A parallel reaction network of first order model well described the characteristics of the ethanol decomposition to acetaldehyde and acetic acid. Utilisation of the high-pressure steam oxidation process can overcome the problem of pressure tightness of the reactor in supercritical water oxidation, and the process can be employed in practical facilities.

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