Fuel

Journal: Fuel

Publisher

Elsevier

ISSN

0016-2361

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Publications1 - 10 of 63

A two-zone solar-driven gasifier concept
Kruesi, M.; Jovanovic, Z.R.; Steinfeld, Aldo (2014)
Fuel
Neat polyoxymethylene dimethyl ether in a diesel engine; part 1: Detailed combustion analysis
Barro, Christophe; Parravicini, Matteo; Boulouchos, Konstantinos (2019)
Fuel
Reduced order modeling of the Shell–Prenflo entrained flow gasifier
Gazzani, Matteo; Manzolini, Giampaolo; Macchi, Ennio; et al. (2013)
Fuel
Experimental investigation of pilot-fuel combustion in dual-fuel engines
Srna, Aleš; von Rotz, Beat; Herrmann, Kai; et al. (2019)
Fuel
Morphology and size of soot from gas flares as a function of fuel and water addition
Trivanovic, Una; Sipkens, Timothy A.; Kazemimanesh, Mohsen; et al. (2020)
Fuel
A large-scale, laboratory turbulent diffusion flame was used to study the effects of fuel composition on soot size and morphology. The burner and fuels are typical of those used in the upstream oil and gas industry for gas flaring, a practice commonly used to dispose of excess gaseous hydrocarbons. Fuels were characterized by their carbon-to-hydrogen ratio (from 0.264 to 0.369) and their volumetric higher heating value (HHVv) (from 35.8 to 75.2 MJ/m3). Transmission electron microscopy (TEM) was used to assess primary particle and aggregate size, showing that the scaling of primary particle size to aggregate size was roughly the same for all of the considered fuels (dp = 16.3(da,100 [nm]/100)0.35). However, fuels with higher HHVv produced substantially larger soot aggregates. A scanning mobility particle sizer (SMPS) was also used (i) to measure mobility diameter distributions and (ii) in tandem with a centrifugal particle mass analyzer (CPMA) to determine the two-dimensional mass-mobility and effective density-mobility distributions using a new inversion approach. The new approach was shown to improve internal consistency of inferred morphological parameters, though with a shift relative to median-based analysis of the tandem data. Raman spectroscopy was used to quantify the degree of graphitization in the soot nanostructure. The addition of water to the fuel consistently reduced the soot yields but did not affect other morphological parameters. Larger aggregates also tended to have larger primary particles and higher Raman D/G ratios suggesting larger graphitic domains.
Core-scale modelling of cyclic creep deformation caused by cyclic CO₂ injection and storage in unconventional reservoirs
Rezaeyan, Amirsaman; Hamdi, Hamidreza; Ghanizadeh, Amin; et al. (2025)
Fuel
Cyclic CO2 injection, followed by soaking and production—commonly referred to as “Huff-n-Puff” (HnP)—can be used to enhance oil recovery, while mitigating greenhouse gas emissions, from unconventional reservoirs. The cyclic loading and unloading stresses associated with HnP induces cyclic creep deformation in the reservoir. This study aims to investigate the impact of cyclic creep deformation on CO2 storage and enhanced oil recovery (EOR) under varying geomechanical conditions. Intact and fractured core plugs from the Canadian Montney Formation were subjected to single-phase gas flow (gas permeability) measurements under multiple cycles of loading and unloading stresses, with rock and flow properties (e.g., permeability, porosity) determined for each cycle. The experimental data informed hydromechanical models incorporating various deformation scenarios (rigid, elastic, weakly elastic, and cyclic creep) and coupled with multiphase, multicomponent flow and transport models. Results reveal that cyclic creep deformation diminishes CO2-EOR potential by reducing permeability and porosity with each successive cycle, with fractures exhibiting greater reductions compared to the matrix. Accumulated creep deformation results in slower pressure buildup during CO2 injection and a slower depletion rate during oil production. Consequently, CO2 storage is reduced by 18% and 30%, and oil recovery decreases by 5% and 20% in the matrix (pore) and fracture domains, respectively, relative to models without creep deformation. Additionally, free and dissolved CO2 storage volumes increase with each cycle, with fractures enabling significantly higher dissolved CO2 storage (21%) compared to matrix-only storage (6%). A progressive reduction in diffusive CO2 flow across cycles further highlights a transition from diffusion-dominated to convection-dominated flow due to increased effective stress. This study is the first to incorporate cyclic creep deformation into HnP models, demonstrating its critical role in influencing CO2 storage capacity and EOR performance. Ignoring cyclic creep deformation effects can lead to overestimation of CO2 storage capacity and oil recovery, emphasising the importance of accounting for these effects in the design of optimal HnP schemes for oil recovery and sustainable carbon management strategies.
Relative permeability of gas and water flow in hydrate-bearing porous media: A micro-scale study by lattice Boltzmann simulation
Ji, Yunkai; Kneafsey, Timothy J.; Hou, Jian; et al. (2022)
Fuel
The water-gas relative permeability is an important parameter to characterize multiphase flow in sediments. To study the water-gas relative permeability of hydrate-bearing porous media, multiphase flow simulations were carried out at the pore scale using the lattice Boltzmann method. The effects of hydrate saturation and hydrate-growth habits on the water-gas relative permeability, which is scaled by the relative permeability considering the hydrate only, were evaluated in a two-dimensional porous medium. Results show that the increase of hydrate saturation causes the decrease of water-gas effective permeability as expected. However, the effect of hydrate saturation on the water-gas relative permeability is different from that of hydrate saturation on the water-gas effective permeability. The water-gas relative permeability increases with the increase of hydrate saturation in the pore-filling case. The water-gas relative permeability decreases with the increase of hydrate saturation in the grain-coating case. The wettability of solid phase has a different effect on the relative permeability of wetting phase and nonwetting phase. The Jamin effect (phase blocking) was observed and may exist in the production of gas from natural gas hydrate reservoirs. This seriously affects the multiphase flow characteristics. The changes of microscale fluid distribution effect the changes of water-gas relative permeability. The relationship between the water-gas relative permeability and the characterization parameters of microscale fluid distribution was analyzed.
Impact of a split injection strategy on mixing, ignition and combustion behavior in Premixed charge compression ignition combustion
Doll, Ulrich; Barro, Christophe; Todino, Michele; et al. (2021)
Fuel
Mixing, ignition and combustion behavior in a rapid compression and expansion machine operated under Premixed Charge Compression Ignition (PCCI) relevant conditions are investigated by combined passive optical and laser-optical high-speed diagnostics. The PCCI concept is realized using a split injection schedule consisting of a long base load injection and two closely separated short injections near top dead center. Previous studies of close-coupled double injections under constant ambient conditions showed an increased penetration rate of the subsequent fuel spray. However, the aerodynamic gain from the preceding injection is counteracted by the density rise during the compression stroke under transient engine conditions. The study confirms that the rate of mixing of the subsequent fuel spray is significantly increased. Regarding combustion behavior, the thermodynamic analysis exhibits contributions of low temperature oxidation reactions of more than 20% to the total heat release, with a notable amount of unburnt fuel mass varying from 25 to 61%. The analysis of the optical data reveals the multi-dimensional impact of changes in operating parameters on the local mixture field and ignition dynamics. The onset of low temperature reactivity of the first short injection is found to be dominated by the operating strategy, while the location is strongly related to the local mixing state. Low temperature ignition of the consecutive fuel spray is significantly promoted, when upstream low temperature reactivity of the preceding injection is sustained. Likewise, it is shown that high temperature ignition is accelerated by the entrainment of persistent upstream low temperature reactivity.
Effects of ambient CO2 and H2O on soot processes in n-dodecane spray combustion using large eddy simulation
Zhang, Min; Ong, Jiun Cai; Pang, Kar Mun; et al. (2022)
Fuel
In this study, large eddy simulations, coupled a two-equation soot model, are performed to investigate the effects of ambient carbon dioxide (CO2) and water (H2O) additions on the soot formation and oxidation processes in an n-dodecane spray flame. In the soot model, acetylene (C2H2) is soot precursor and surface growth species, while hydroxyl radical (OH) and oxygen (O2) are soot oxidizers. The effect of ambient CO2 and H2O additions on soot formation/oxidation can be separated into thermal and chemical effects. For the thermal effects, the ambient CO2 and H2O additions increase C2H2 but reduce OH formation by lowering the flame temperature. This leads to a higher soot mass formed. On the contrary to the thermal effects, the ambient CO2 and H2O additions reduce the soot formation due to their chemical effects. The reaction CH2∗+CO2↔CH2O+CO is found to be responsible for reducing C2H2 formation. The ambient H2O addition results in a higher OH but lower the C2H2 mass formed owing to the reverse reactions H2+OH↔H2O+H and OH+OH↔H2O+O. Furthermore, the chemical effects is more significant than the thermal effects under the tested conditions. This leads to a lower soot mass formed when adding ambient CO2 and H2O.
Numerical investigation of the autoignition of underexpanded methane jets
Sakellarakis, Vasileios David; Wright, Yuri; Vera Tudela Fajardo, Walter Martin; et al. (2021)
Fuel
This work constitutes a numerical investigation of the autoignition of underexpanded methane jets at high-pressure conditions. Injection pressures from 125 to 500 bar, back pressures from 40 to 125 bar, and pressure ratios between 2.5 and 10 have been targeted. The aim is to identify the effect of the main control variables of gas injection on the autoignition delay and location. To this end, Reynolds-Averaged Navier-Stokes simulations with the model have been carried out for five broad parametric variations. The computational domain represents a Constant Volume Cell with a prototype gas injector. A two-stage workflow enables proper thermodynamic treatment of the conservation equations with real-gas modeling, sufficient resolution for shock structures in the near nozzle area, detailed kinetics described by the San Diego mechanism and treatment of turbulence-chemistry interaction with elliptic Conditional Moment Closure model. The results are interpreted conceptually as an interplay of jet reactivity, effectively described by an exponential dependence on ambient temperature and a power law dependence on ambient pressure, and of jet aerodynamics, empirically described by a quadratic dependence on pressure ratio. Injection temperature is introduced by defining an appropriate characteristic system temperature and a correlation is constructed, whose predictions are juxtaposed against a modified Arrhenius model and measurements from independent experimental studies in literature. The effect of injection variations on ignition location in physical space is also examined.

Publications1 - 10 of 63

Journal: Fuel

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