Gaseous Hydrocarbon Fuels Research Articles

Energy-related carbon dioxide emission factors from combustion of gaseous methane fuels

Abstract The topic of this paper concerns energy-related carbon dioxide emission factors from the combustion of gaseous methane fuels. It is a very current subject, as methane fuels, mainly of fossil origin, are one of the primary energy carriers used in industrial and municipal applications for energy purposes. Consequently, the emitted carbon dioxide contributes to the intensification of the greenhouse effect in the atmosphere. The problem of the quantities characterising emissions from the combustion of methane fuels is complicated by the diversity of these fuels. This paper presents background information on the gaseous hydrocarbon fuels and the composition of the main types of natural gas. The structure of natural gas consumption in Poland, depending on the sectors of application for particular types of natural gas, is presented. On the basis of the existing data, aggregated energy-related carbon dioxide emission factors were estimated and analysed. The analysis was carried out for high-methane natural gas (HM), colliery gas (CG) and nitrified natural gas (N)—for the years 1988–2021. Trends in fuel consumption and energy-related carbon dioxide emission factors were determined for the years 1988–2021.

Effect of nonmetals (B, O, P, and S) doped with porous g-C3N4 for improved electron transfer towards photocatalytic CO2 reduction with water into CH4

Photocatalytic conversion of carbon dioxide (CO2) into gaseous hydrocarbon fuels is an auspicious way to produce renewable fuels in addition to greenhouse gas emission mitigation. In this work, non-metals (B, O, P, and S) doped graphitic carbon nitride (g-C3N4) was prepared via solid-state polycondensation of urea for photocatalytic CO2 reduction into highly needed methane (CH4) with water under UV light irradiation. The various physicochemical characterization results reveal the successful incorporation of B, O, P, and S elements in the g-C3N4 matrix. The maximum CH4 yield of 55.10 nmol/(mLH2O.gcat) over S-doped g-C3N4 has been obtained for CO2 reduction after 7 h of irradiation. This amount of CH4 production was 1.9, 1.4, 1.7, and 2.4-folds higher than B, O, P and bare g-C3N4 samples. The doping of S did not enlarge the surface area and photon absorption ability of the g-C3N4 sample, but this significant improvement was evidently due to effective charge separation and migration. The observed results imply that the doping of non-metal elements provides improved charge separation and is an effective way to boost photocatalyst performance. This work offers an auspicious approach to design non-metal doped g-C3N4 photocatalysts for renewable fuel production and would be promising for other energy application.

Experimental and modeling of autoignition of gaseous hydrocarbon fuels in the presence of H2 and C2H4

The focus of the present work is to understand the effect of H2 and C2H4 on the ignition characteristics of other gaseous fuels, namely, CH4, C2H6 and C3H6. Atmospheric-pressure flow reactor experiments were performed to measure the ignition delay times of CH4, C2H6 and C3H6 binary mixtures with H2 or C2H4 between 800 and 950 K. Most of the experiments were conducted at stochiometric conditions with 21% O2. Select tests were performed to examine the effects of equivalence ratios and oxygen concentrations. Ignition delay time were also measured for ternary mixtures of C3H6-C2H4-H2 at select conditions. Based on the experimental data, the overall effectiveness of H2 or C2H4 in reducing the ignition delay time of the binary mixtures can be listed in the following order: CH4 > C3H6 > C2H6. The experimental data were used to refine and validate the chemical kinetic mechanism for allyl-HO2 system relevant to low-temperature ignition chemistry of C3H6. A detailed sensitivity analysis is presented to identify the important reaction pathways, and their implications for the experimental observations are discussed. Monte Carlo simulations were used to quantify the model uncertainty for ignition delay time predictions, and to identify reactions that have significant contribution to the model uncertainty. Among the binary mixtures studied, CH4-H2 mixture produced the largest model uncertainty, primarily due to the sensitive reactions involving HO2 radical.

Impact of methanol use in a diesel engine on workflow performance

World experience in solving environmental problems associated with the use of diesel engines as propulsion systems allows us to conclude that the most acceptable solution to the problem of reducing exhaust gas toxicity and improving environmental performance is the use of alternative fuels. Gaseous hydrocarbon fuels (natural gas and propane-butane), which are environmentally friendly motor fuels, are most widely used in road transport. Among liquid alternative fuels, fuel ethanol and methanol are the most common. Vyatka state agricultural Academy has been conducting research on converting internal combustion engines to synthetic motor fuel for many years. The article presents the results of using methanol as a motor fuel when it is fed directly into the diesel combustion chamber through a multi-jet nozzle. Indicator diagrams obtained in the maximum torque mode are analyzed.

Применение низкотемпературных технологий для предотвращения аварийных ситуаций на море и реках при добыче, эксплуатации и транспортировке углеводородного сырья

The paper highlights the chemically hazardous objects of marine and river infrastructure: offshore drilling platforms and oil production platforms; pipelines transporting liquid and gaseous hydrocarbon fuels along the sea bottom and above the ground; marine tankers transporting oil, fuel oil, gaseous and liquid ammonia; coastal terminals handling and shipping hydrocarbon raw materials, distillation products; gas producing plants and oil refineries; storage facilities for chemi-cally hazardous substances, etc. There are proposed new technologies for combating oil emissions during deep-water drilling, as well as for safe ways of transporting hydrocarbons through subsea pipelines and by oil tankers. These technologies are based on the methods of using low-temperature freons and cryogenic liquids. There are considered the methods of using machine cooling technologies, where the cascade refrigeration units work on various refrigerants, as well as using solid carbon dioxide and liquid nitrogen. Liquid nitrogen having a low boiling point (about minus 196C) has a higher rate of seawater freezing and forms stable ice layers on flat and cylindrical surfaces. There are given the examples of the experimental data to determine the growth rate of ice in the water frozen by liquid nitrogen. There has been given the chart of an underwater cryo-cuvette consisting of a metal panel with sockets, heat-insulated barrels, a tank for storing liquid nitrogen, 
 a nozzle for filling the cryoagent, adjusting eyebolts, an object for freezing and transportation, and a safety valve. The underwater cryo-cuvette is designed to work with barrel-shaped objects. Envi-ronmental safety of transportation and production of natural hydrocarbon raw materials is signifi-cantly improved in the course of operation of the new technologies.

Study on relationships between detonation characteristics and molecular structure parameters of hydrocarbon fuels

Detonation characteristics of hydrocarbon fuels are important indexes for their safety evaluation and protection. To investigate the detonation characteristic of alkane homologs series and the influence of different molecular energies, alkane homologs series’ critical energy to direct detonation (hereinafter related to as critical energy) and detonation cellular width were measured by a self-designed shock tube. Then, the molecular total energy (E) and bond dissociation energy (BDE) of fuel molecules were calculated by the quantum chemistry method. After the comparison between detonation characteristics and molecular energies, it is found that for alkane homologs series, molecular total energy was found to have a good exponent relation between critical energy and detonation cellular width, which indicated that the detonation sensitivity of alkane homologs series can be predicted based on total energy of fuel molecules with preferable accuracy. Extra experiment and calculation was also carried out on gaseous hydrocarbon fuels (ethane, ethylene and acetylene) with same carbon atom number. Results indicated that the bond dissociation energy may have the impact on the detonation cellular width for these three gaseous fuels. The bigger bond dissociation energy leads to smaller cellular width.

Effect of Char Loading on Reduction Kinetics of Cu-Based Oxygen Carriers in a Drop-Tube Fluidized-Bed Reactor at Temperatures from 850 to 1100 °C: Experiment and CFD Modeling

Chemical-looping combustion with oxygen uncoupling (CLOU) is a process using gaseous or solid hydrocarbon fuels and is a promising carbon capture and storage (CCS) technology. In CLOU, combustion o...

Effects of Various Compositions of the Fuel—Air Mixture on the Pulse Detonation Engine Performance

The objective of the present analysis is to investigate the effect of gaseous hydrocarbon fuels, such as Octane C8H18, Hexane C6H14, and Pentane C5H12 on the cyclic combustion process in an obstructed channel of the pulse detonation engine. Three-dimensional reactive Navier-Stokes equations are used to simulate the combustion mechanism of stoichiometric hydrocarbon fuels along with a one-step reaction model. The fuel is injected at atmospheric pressure and temperature and is ignited with pre-heated air. The investigation shows that initially a high-temperature combustion wave propagates with the local speed of sound; it creates turbulence after colliding with obstacles, resulting in an increase to supersonic flame speeds. Therefore, different values of the combustion flame propagation speed, combustion efficiency and impulse per unit area are obtained for these fuels. The detonation speed in the hexane-air mixture is about 5.8% lower than the detonation speed predicted by the NASA CEA400 code. However, it is observed that the octane fuel reduces the deflagration-to-detonation transition run-up distance as compared to other fuels.

Catalytic transfer hydrogenation and characterization of flash hydrolyzed microalgae into hydrocarbon fuels production (jet fuel)

Oil-laden biofuel intermediate (BI) from flash-hydrolyzed microalgae was characterized, pyrolyzed, and subjected to catalytic transfer hydrogenation (CTH) to produce both gaseous and liquid hydrocarbon fuels. The BI was characterized by TGA and FTIR that revealed significant triglyceride, evidenced by CO bond with insignificant level of carbohydrates and proteins. Thermogravimetric analysis (TGA) indicated that the BI could be thermally decomposed at 400 °C. Pyrolysis of the BI engendered mainly gaseous hydrocarbon (alkenes) with high heating value (HHV) of 48.5 kJ/mol at 850 °C. Energy of activation for the pyrolytic process was estimated to be 115–300 kJ/mol. Optimization of oil extraction from the BI was performed via design of experiment. The oil was subjected to CTH over NiOx-CoOx-MoOx-zeolite using 2-propanol as hydrogen donor in a 30-ml batch reactor at a temperature range of 390–420 °C and autogenic pressure of 24–27 bar, leading to fatty acid conversion of 99–100%. The main liquid products obtained from the CTH were iso-alkanes (41%), cyclo-alkanes (35%), aromatics (5%), n-alkanes (14%), and alkenes (5%). Kinetics of the CTH showed first order with activation energy of 176 kJ/mol.The catalyst was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Brunaeur-Emmett-Teller (BET) adsorption and desorption, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and TGA. The catalyst revealed cubic structure, which was maintained after 5 h of CTH reaction. Present in both the fresh and the used catalysts were oxides of alkali and transition metals. The active sites of the catalyst were dominated by Co3+, Ni2+, and Mo6+.

Fabrication and wave absorption property of Co[sbnd]C material prepared by direct detonation of gaseous hydrocarbon fuels

The gaseous hydrocarbon fuels were ignited by a 20 J high energy electric spark in a gaseous detonation tube. The possibility of direct detonation and the stable propagation of detonation wave in the tube were analysed. The cobalt(III) acetylacetonate (Co(acac)3) was decomposed by high temperature generated via gaseous detonation to prepare CoC materials. The characterization results indicated that the CoC materials prepared by 2H2O2 detonation consisted of nano-sized Co@C particles and micron-sized CNTs in length. While the CoC materials fabricated by CH4-2O2 and C2H2-2O2 detonation were micron-sized Co@C particles. The morphology of CoC materials were greatly affected by the combustion heat of the gaseous hydrocarbon fuels, the higher the combustion heat, the larger particle size of Co@C. The degree of graphitization of Co@C was low, while the crystallinity of Co was relatively high. The growth mechanism of CoC materials was discussed by using detonation collision model and ZND model. The minimum RL value of Co@C particles-paraffin mixture was −3.8 dB at 13.9 GHz with thickness of 3 mm.

Mixing characteristics of cracked gaseous hydrocarbon fuels in a scramjet combustor

High-performance hydrocarbon-fuelled scramjet engines require efficient fuel-air mixing due to the relatively short flow residence time through the combustor. At high temperatures, hydrocarbon fuels react endothermically and absorb thermal energy from the surroundings. The process known as cracking becomes essential at high Mach numbers to increase the total heat-sink capacity of the fuel. This study presents the results of chemically frozen numerical simulations that investigate the mixing characteristics of cracked gaseous heavy hydrocarbon fuels injected through a circular, flush-wall porthole injector. The mixing characteristics of fuel compositions representing cracking efficiencies ranging from 0 to 100% are investigated. The mixing rates and flow structures are found to change with fuel compositions. As the cracking increases, the mixing and streamwise circulation increase for an injectant. However, the jet penetration and stagnation pressure losses decrease. The streamwise circulation is found to have a strong influence on the mixing, the injection pressure on the jet penetration and the strength of the bow shock on stagnation pressure losses. Overall, it is shown that there are mixing benefits to be gained by injecting cracked hydrocarbon fuels compared to heavy uncracked fuels in scramjets.

Examining and Modeling Oxygen Uncoupling Kinetics of Cu-Based Oxygen Carriers for Chemical Looping with Oxygen Uncoupling (CLOU) in a Drop Tube Fluidized Bed Reactor

Chemical looping combustion with oxygen uncoupling (CLOU) is a promising carbon capture and storage (CCS) technology for conversion of gaseous and solid hydrocarbon fuels where the release of gaseo...

Certain ways for efficiency improving of liquid and gaseous hydrocarbon and nitrogen-containing fuels for flying vehicles engines

Certain ways for efficiency improving of liquid and gaseous hydrocarbon and nitrogen-containing fuels for flying vehicles engines

Technical Assessment of Different Operating Conditions of an On-Board Autothermal Reformer for Fuel Cell Vehicles

This paper evaluates the performance of a fuel cell/battery vehicle with an on-board autothermal reformer, fed by different liquid and gaseous hydrocarbon fuels. A sensitivity analysis is performed to investigate the system behavior under the variation of the steam to carbon and oxygen to carbon ratios. This is done in order to identify the most suitable operating conditions for a direct on-board production of hydrogen to be used in a high temperature polymer electrolyte membrane fuel cell. The same system should be able to process different fuels, to allow the end-user to freely decide which one to use to refuel the vehicle. Hence, the obtained operating conditions result in a trade-off between system flexibility as the feeding fuel changes, CO poisoning effect on the fuel cell and overall efficiency. The system is thus coupled to a high temperature fuel cell, modeled by means of a self-made tool, able to reproduce the polarization curve as the input syngas composition varies, and the overall system is afterwards tested on a plug-in fuel cell/battery vehicle simulator, in order to provide a thorough feasibility analysis, focusing on the entire system efficiency. Results show that a proper energy management strategy can mitigate the effect of the fuel variation on the reformer efficiency, allowing for good overall powertrain performance.

INFLUENCE OF HIGH ALTITUDE ON COMBUSTION EFFICIENCY AND RADIATION FRACTION OF HYDROCARBON FIRES

Fire behaviors of three gaseous hydrocarbon fuels were experimentally measured and compared at two different altitudes (Lhasa city, 64 kPa at an altitude of 3650 m; Hefei city, 100 kPa at an altitude of 50 m). The heat release rates were calculated through a simplified thermochemistry based on the measured concentrations of O-2 and CO2 in the exhaust duct, then the combustion efficiencies and the radiation fractions were compared at the two altitudes. The heat release rates and combustion efficiencies were higher at lower pressure, and the overall temperatures of methane fires rose at a lower pressure. The radiative heat fluxes and radiation fractions at a low pressure were smaller than those at a normal pressure, while the smoke transmittances of acetylene fires at a low pressure were higher.

Synthesis Gas Biorefinery.

Synthesis gas or syngas is an intermediate, which can be produced by gasification from a variety of carbonaceous feedstocks including biomass. Carbon monoxide and hydrogen, the main constituents of syngas, can be subjected to a broad range of chemical and microbial synthesis processes, leading to gaseous and liquid hydrocarbon fuels as well as to platform and fine chemicals. Gasification of solid biomass differs from coal gasification by chemical composition, heating value, ash behavior, and other technical and biomass related issues. By thermochemical pre-treatment of lignocellulose as the most abundant form of biomass, for example, by torrefaction or fast pyrolysis, energy dense fuels for gasification can be obtained, which can be used in the different types of gasifiers available today. A number of pilot and demonstration plants exist, giving evidence of the broad technology portfolio developed so far. Therefore, a syngas biorefinery is highly flexible in regard to feedstock and product options. However, the technology is complex and does not result in competitive production costs today. Added value can be generated by suitable integration of thermochemical, biochemical, and chemical processes.

Overview of Performance, Application, and Analysis of Rotating Detonation Engine Technologies

Recent accomplishments related to the performance, application, and analysis of rotating detonation engine technologies are discussed. The pioneering development of optically accessible rotating detonation engines coupled with the application of established diagnostic techniques is enabling a new research direction. In particular, chemiluminescence images of detonations propagating through the annular channel of a rotating detonation engine are reported and appear remarkably similar to computational fluid dynamic results of rotating detonation engines published in the literature. Specific impulse measurements of rotating detonation engines and pulsed detonation engines are shown to be quantitatively similar for engines operating on hydrogen/air and ethylene/air mixtures. The encouraging results indicate that rotating detonation engines are capable of producing thrust with fuel efficiencies that are similar to those associated with pulsed detonation engines while operating on gaseous hydrocarbon fuels. A rotating detonation engine is coupled with a turboshaft engine for the first time. The performance of the rotating detonation engine gas turbine engine is similar to or better than that of the conventional gas turbine engine across a broad range of operating conditions. Realizing the advantages of pressure gain combustion in rotating detonation engines is enabling new combustion system design opportunities and supporting the development of efficient and sustainable power and propulsion technologies.

Zinc-copper oxide coated monolithic reactors for high capacity hydrogen sulphide removal from gaseous streams

Production of fuel-cell grade hydrogen via reforming of gaseous hydrocarbon fuels requires the design and implementation of efficient formulations, which incorporate high performance materials for the removal of undesired impurities; notably H2S. To this respect, the present study relates to the preparation and parametric evaluation of small-scale honeycomb structured flow-through reactors, coated with an in-house synthesized ZnO/CuO, 50%mol/50%mol, sorbent. Experimental tests involved quantification of the H2S trapping capacity and efficiency of the coated monoliths by monitoring the evolution of H2S concentration at the reactor outlet for known H2S feeds at the reactor inlet. The de-H2S performance of the coated monoliths was examined at reactor temperatures ranging from 160 °C to 400 °C, under two different synthetic mixtures containing a) 30%vol H2, 32%vol H2O, N2 balance and b) 30%vol H2, 32%vol H2O, 6.5%vol CO2, 4.5%vol CO, N2 balance. Space velocities at the reactor ranged from 20,000 to 60,000 h−1 for the experiments designed to examine trapping capacity and from 10,000 to 90,000 h−1 for the experiments designed to examine trapping efficiency. The breakthrough curves obtained proved that the particular formulation can provide a very efficient solution, particularly for the case of decentralized applications, for which system compactness is of prime importance. Total capture capacities up to a targeted H2S breakthrough value of 0.1 ppmv at the reactor outlet varied between 5 and 25 (gsulphur/100 × gsorbent). This value depended on reactor temperature and flow conditions, gas composition, monolith loading and monolith cell density.

Determination of Optimum Length of Flat Flames in Tube Furnaces Having Bottom Burners

Correlations of resultant heat transfer efficiency criteria with length of flat flames are obtained for various gaseous and liquid hydrocarbon fuels by mathematical modeling of complex heat transfer in narrowchamber tube furnaces using zonal method. Thanks to this, such temperature fields can be created in the furnace by varying the length of flat flames as would ensure the required uniformity of heat supply at nearmaximum value of integral heat received by a tubular screen.

Flame speed measurements in aluminum suspensions using a counterflow burner

The burning velocity is a fundamental parameter in combustion that has been accurately measured with different methods for a variety of gaseous and liquid hydrocarbon fuels. However, it is still unclear whether this concept also applies to the combustion of particulate-fuel suspensions. Attempts to measure the burning velocity in particulate suspensions have been made using a range of experimental techniques, but no study has yet attempted to reconcile the results from different studies. The present work reports the first realization of a stabilized aluminum flame using a counterflow burner. The flow is tracked using Particle Image Velocimetry and the flame speed is obtained as a function of aluminum concentration. The results are then compared to previous data obtained for stabilized flames, spherically-expanding flames, and flames propagating in tubes. The results are in reasonable agreement, given the experimental uncertainties in all of the techniques employed to date, suggesting that the notion of a laminar burning velocity may be applied to suspensions of particulate fuels.