Fuel pyrolysis through porous media: Coke formation and coupled effect on permeability

Fau, Guillaume; Gascoin, Nicolas; Gillard, Philippe; Bouchez, Marc; Steelant, Johan

doi:10.1016/j.jaap.2012.02.005

Cited by 41 publications

(40 citation statements)

References 22 publications

(3 reference statements)

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“…As a consequence, the overall effect of the heating rate is the one observed in Figure 8. This result is of major importance because this confirms previous results from numerical and experimental multiphysics studies [22], [29]. The light alkenes are formed preferably when the fuel is heated strongly and rapidly; that is to say when the heating rate is high.…”

Section: Table 4 Example Of Data Post-processing According To the Desupporting

confidence: 87%

Flash Pyrolysis of High Density PolyEthylene

Gascoin

Fau²,

Gillard³

et al. 2013

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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The inert and oxidative flash pyrolysis of High Density Poly-Ethylene (HDPE) is studied up to 20 000 K.s-1, under pressure up to 3.0 MPa and at temperature ranging from 1000 K to 1500 K. These conditions are considered to represent those waited onboard a hybrid rocket engine using HDPE as solid fuel. Recycling applications may also find some interest. The pyrolysis products are analysed by Gas Chromatograph, Flame Ionisation Detector and Mass Spectrometer to quantify the effects of each physical parameter on the HDPE decomposition. The classical products distribution diene-alkene-alkane for each carbon atoms number is shown to be modified at such high temperature because of the pyrolysis of primary products. The pressure effect, which is generally neglected in HDPE pyrolysis studies found in open literature, is proved to be a major factor (up to one order of magnitude on the ethylene mass fraction). The heating rate presents noticeable consequences on the pyrolysis products distribution with a larger formation of light species while heavier ones are favoured under oxidative pyrolysis conditions. The experimental data should serve in the future to improve the accuracy of kinetic mechanisms for later use in numerical computing.

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Section: Table 4 Example Of Data Post-processing According To the Desupporting

confidence: 87%

Flash Pyrolysis of High Density PolyEthylene

Gascoin

Fau²,

Gillard³

et al. 2013

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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show abstract

“…4) and exp  is the experimental one. A direct search algorithm provided by the ''Global Optimization'' Toolbox of Matlab® is used to solve the bound constrained optimization problem of relation (5). Unlike traditional optimization methods which need gradient or higher derivatives information to search for an optimal point, this optimization algorithm does not require any information about the gradient of the objective function.…”

Section: Mathematical Procedures Of Darcian's and Forchheimer's Permementioning

confidence: 99%

“…The Solid Oxide Fuel Cell (SOFC) for example could be used, mostly if species like hydrogen and light hydrocarbons are available onboard. In the meantime, liquid fuel (stored for propulsion application when burned in the combustion chamber) may encounter temperature that pyrolysis it and that produces light species [1][2][3][4][5] . Since the higher the H2 or light hydrocarbons content, the longer the life time of the fuel cell, using heavy fuel would decrease the life time of the fuel cell.…”

Section: Introductionmentioning

confidence: 99%

Effect of Flow Configuration on Darcian and Forchheimer Permeabilities Determination in a Porous Composite Tube

Najmi

Tabach

Chetehouna³

et al. 2015

20th AIAA International Space Planes and Hypersonic Systems and Technologies Conference

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Using Fuel Cell on board of aircraft imposes to extract light species (such as Hydrogen and light hydrocarbons) from the liquid fuel which is stored and used, possibly attemperatures where a fuel pyrolysis occurs. Natural porosity of composite material could be used to filtrate the selected species. Hence the permeability of the porous media becomes one of the key parameter to be accurately measured. It is often determined experimentally in laboratory with disc samples (outlet of the flow is achieved through the porous material) and normal flow. However, this configuration is far from the realistic one consisting of tubes (a main flow is found additionally to the one through the material, tangential permeability). Therefore, the effect of a second outlet on the Darcy's and Forchheimer's permeabilities characterization should be studied (despite the permeability is an intrinsic property of the material itself and it should not be dependent on the test apparatus). This paper focuses on a new way of using an existing test bench for the determination of Darcy's and Forchheimer's permeabilities of C/SiC porous composite tube by taking two outlets into account. Operating parameters (temperature, pressure and mass flow rate) are measured for three different configurations: i) secondary outlet (S.O) is 0% open ii) S.O is 50% open and iii) S.O is 100% open. Then Darcy's and Forchheimer's permeabilities are computed by ISO and P 2 methodsusing a direct search algorithm. Obtained results from different methods are compared and discussed. They are in agreement with the literature data which guarantees the reliability of the test bench and of related measures. Nomenclature Acronym CMC = Ceramic Matrix Composite PO/SO ratio = ratio of the flowrate from the Primary Outlet over the one from the Secondary Outlet P.O = Primary outlet 1 2 S.O = Secondary outlet LatinLetters ag = Grain area dg = Grain diameter dp = Pore diameter KD = Darcian's permeability KF = Forccheimer's permeability L = Length Pinlet = Pressure inlet Poutlet = Pressure outlet Re = Reynolds pore number T = Temperature V = Velocity Greek Letters ε = Overall open porosity µ = Dynamic viscosity ρ = Density

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“…In previous works 2, 12 , we experimentally determined the mean permeability by using the Brinkman equation. Several porous materials through which both reactive and nonreactive fluids flow were examined, as was the effect of temperature.…”

Section: Introductionmentioning

confidence: 99%

Modeling the spatio-temporal evolution of permeability during coking of porous material

Tabach¹,

Chetehouna²,

Gascoin³

et al. 2015

20th AIAA International Space Planes and Hypersonic Systems and Technologies Conference

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International audienceTranspiration cooling is one of the most efficient cooling techniques, but one which generates complex phenomena that are difficult to model, and this all the more in that a reactive fluid such as an endothermic fuel is used. Above a certain temperature, such fuel is pyrolysed and, thanks to its endothermic behaviour, this ensures the active cooling of the hot walls of the combustion chamber. However, one of the consequences of this thermal decomposition is the unwanted formation of coke which blocks the porous material (both on the surface and in the interior). This gradual blocking reduces the material's permeability and thus the efficiency of the cooling system. Modelling the permeability distribution of porous materials is thus a key parameter in better understanding transpiration cooling. The present article shows several models intended to estimate the variation in time and space of the permeability of a material (stainless steel) during its coking. The fluid circulating in this porous material is n-dodecane that is maintained at a high temperature. Following a presentation of the measurement device and the measured experimental data of the mean permeability, two categories of model are studied, notably discontinuous mesh models (with 2 and 3 meshes) and continuous analytical models (linear and exponential). The results obtained show that discontinuous models with 2 and 3 meshes are very close in measuring the temporal evolution of the thickness of the coked zone of the porous material. They also revealed that the exponential model is more appropriate than the linear model in estimating the spatiotemporal evolution of the permeability. Additionally, the evolution of the coking rate in the porous material was determined as a function of time and the results show behaviour similar to that indicated in the literature. Lastly, the average Darcy permeability was linked to the mass of coke deposit in the porous material, the result of which reveals a quasi-linear decrease. Nomenclature Latin letters e = Sample thickness e j [m] = Thickness of each layer j K = Hydraulic conductivity tensor K D = Darcian's permeability K Davg = Average Darcian permeability K D0 = Initial Darcian permeability K F = Forchheimer's permeability K j = Darcian permeability of each layer j P = Pressure ΔP = Pressure drop t = time T = temperature V = Mean fluid velocity Greek Letters ε = Overall open porosity μ = Dynamic viscosity ρ = Fluid density ø = Diamete

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Fuel pyrolysis through porous media: Coke formation and coupled effect on permeability

Cited by 41 publications

References 22 publications

Flash Pyrolysis of High Density PolyEthylene

Flash Pyrolysis of High Density PolyEthylene

Effect of Flow Configuration on Darcian and Forchheimer Permeabilities Determination in a Porous Composite Tube

Modeling the spatio-temporal evolution of permeability during coking of porous material

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