Flame acceleration and the development of detonation in fuel–oxygen mixtures at elevated temperatures and pressures

Thomas, G.O.

doi:10.1016/j.jhazmat.2008.07.105

Cited by 33 publications

(14 citation statements)

References 22 publications

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“…Besides its remarkable therapeutic potential, H 2 has several characteristic burdens that need to be overcome before clinical application: inflammability, low solubility, and high tissue/substance permeability . First, gaseous H 2 is potentially inflammable, and 10% seems to be the safety limit for preventing explosion . Ideally, <4% seems preferable to secure the safety of the patient as well as the medical staff .…”

mentioning

confidence: 99%

“…(22,23) First, gaseous H 2 is potentially inflammable, and 10% seems to be the safety limit for preventing explosion. (24) Ideally, <4% seems preferable to secure the safety of the patient as well as the medical staff. (22,25) Although an aqueous H 2 solution is safe and convenient for handling, (21) its solubility is very low, and the maximal concentration under 1 atm is just 1.6 ppm.…”

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confidence: 99%

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Hydrogen Flush After Cold Storage as a New End‐Ischemic Ex Vivo Treatment for Liver Grafts Against Ischemia/Reperfusion Injury

Tamaki¹,

Hata²,

Okamura³

et al. 2018

Liver Transpl

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Cold storage (CS) remains the gold standard for organ preservation worldwide, although it is inevitably associated with ischemia/reperfusion injury (IRI). Molecular hydrogen (H ) is well known to have antioxidative properties. However, its unfavorable features, ie, inflammability, low solubility, and high tissue/substance permeability, have hampered its clinical application. To overcome such obstacles, we developed a novel reconditioning method for donor organs named hydrogen flush after cold storage (HyFACS), which is just an end-ischemic H flush directly to donor organs ex vivo, and, herein, we report its therapeutic impact against hepatic IRI. Whole liver grafts were retrieved from Wistar rats. After 24-hour CS in UW solution, livers were cold-flushed with H solution (1.0 ppm) via the portal vein (PV), the hepatic artery (HA), or both (PV + HA). Functional integrity and morphological damages were then evaluated by 2-hour oxygenated reperfusion at 37°C. HyFACS significantly lowered portal venous pressure, transaminase, and high mobility group box protein 1 release compared with vehicle-treated controls (P < 0.01). Hyaluronic acid clearance was significantly higher in the HyFACS-PV and -PV + HA groups when compared with the others (P < 0.01), demonstrating the efficacy of the PV route to maintain the sinusoidal endothelia. In contrast, bile production and lactate dehydrogenase leakage therein were both significantly improved in HyFACS-HA and -PV + HA (P < 0.01), representing the superiority of the arterial route to attenuate biliary damage. Electron microscopy consistently revealed that sinusoidal ultrastructures were well maintained by portal HyFACS, while microvilli in bile canaliculi were well preserved by arterial flush. As an underlying mechanism, HyFACS significantly lowered oxidative damages, thus improving the glutathione/glutathione disulfide ratio in liver tissue. In conclusion, HyFACS significantly protected liver grafts from IRI by ameliorating oxidative damage upon reperfusion in the characteristic manner with its route of administration. Given its safety, simplicity, and cost-effectiveness, end-ischemic HyFACS may be a novel pretransplant conditioning for cold-stored donor organs.

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confidence: 99%

mentioning

confidence: 99%

Hydrogen Flush After Cold Storage as a New End‐Ischemic Ex Vivo Treatment for Liver Grafts Against Ischemia/Reperfusion Injury

Tamaki¹,

Hata²,

Okamura³

et al. 2018

Liver Transpl

View full text Add to dashboard Cite

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“…For this reason, detonation cell widths (λ) were calculated from CELL-H2 (Gavrikov et al, 2000) to parameterize the simulations on the detonation propagation limits. Detonation velocities must be above 1820 m/s (0.92 DCJ) at the end of the detonation tube for reliable and stable propagation, for which detonation cell width is equal to the tube diameter (λ = 36 mm) and λ = D is recognized as a practical criterion for the propagation limit due to the uncertainties on cell sizes near the limit (Thomas, 2009;Dupré et al, 1991). Meanwhile, for CJ detonation, the cell width is 10 mm.…”

Section: Fig 2 High Pressure and Temperature Patch With Circular Rementioning

confidence: 99%

2-D Simulation with OH* Kinetics of a Single-Cycle Pulse Detonation Engine

Maciel

Marques²

2019

JAFM

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Two-dimensional computational fluid dynamics (CFD) simulation with selected kinetics for H2-air mixture of a hydrogen-fuelled single-pulse detonation engine were performed through ANSYS FLUENT commercial software for diagnostic purposes. The results were compared with Chapman-Jouguet (CJ) values calculated by the CEA (Chemical Equilibrium with Applications) and ZND (Zel'dovich-Neumann-Döring) codes. The CJ velocities and pressures, as the product velocities are in agreement, however, the CJ temperatures are too higher for 2-D simulations; as a consequence, the sound velocities were overpredicted. OH* kinetics added to the reaction set allowed visualization of the propagation front with several detonation cells showing a consistent multi-headed detonation propagating in the whole tube. The detonation front was slightly perturbed at the end of the tube with inclination of front edge and fewer cell numbers, and more significantly at the nozzle entrance with velocity reduction, resulting in a weak and unstable detonation. OH* images showed the detonation reaction zone decoupled from the shock front with disappearance of cellular structure. The inclusion of OH* reaction set for CFD simulation coupled to kinetics is demonstrated to be an excellent tool to follow the detonation propagation behaviour.

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“…Other than that, Proust [16] also suggested that the interaction between self-acceleration and reflective wave is the main mechanism contributing to the fast flame development. Thomas et al [17] and Brown et al [18] observed that flame instabilities in preheated zone result in the flame perturbation leading to flame acceleration and create a secondary explosion. Furthermore, Liberman et al [19], observed the shock-wave interaction of premixed ethylene/air mixture.…”

Section: Introductionmentioning

confidence: 99%

Effect of pipe size on acetylene flame propagation in a closed straight pipe

Zubaidah¹,

Kasmani²,

Mustafa³

et al. 2017

J. MECH. ENG. SCI.

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The understanding of flame propagation mechanism in a tube or pipe as a function of scale is needed to describe explosion severity. Acetylene is an explosively unstable gas and will lead to a violent explosion when ignited. To achieve the goal, an experimental study of premixed acetylene/air mixture at stoichiometry concentration was carried out in a closed straight pipe with different sizes of L/D (ratio of length to diameter) to examine the flame propagation mechanism. Pipes with L/D=40 and 51 were used. From the results, it was found that the smaller pipe with L/D=40 enhanced the explosion severity by a factor of 1.4 as compared to that of the bigger pipe with L/D=51. The compression effect at the end of the pipe plays an important role to attenuate the burning rate, leading to higher flame speeds and hence, increases the overpressure. In the case of L/D=40, the compression effect is more severe due to the larger expansion ratio, and this phenomenon would decrease the quenching effect and subsequently promote flame acceleration. Fast flame speeds of up to 600 m/s were measured in the smaller pipe during explosion development. From the results, it can be seen that the compression effect plays a major role in contributing to the higher burning rate and affects the overall explosion and flame speed development. Furthermore, the compression effect is more severe in the smaller pipe that leads to the detonation-like event. This mechanism and data are useful to design a safety device to minimise explosion severity.

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Flame acceleration and the development of detonation in fuel–oxygen mixtures at elevated temperatures and pressures

Cited by 33 publications

References 22 publications

Hydrogen Flush After Cold Storage as a New End‐Ischemic Ex Vivo Treatment for Liver Grafts Against Ischemia/Reperfusion Injury

Hydrogen Flush After Cold Storage as a New End‐Ischemic Ex Vivo Treatment for Liver Grafts Against Ischemia/Reperfusion Injury

2-D Simulation with OH* Kinetics of a Single-Cycle Pulse Detonation Engine

Effect of pipe size on acetylene flame propagation in a closed straight pipe

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