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[Display omitted] • The well-designed rapidly-mixed swirl burner anchors compact ammonia/air flames. • Gliding arc discharges significantly extend the lean blow-off margin by repetitive ignition. • The flame structure and intermediate plasma chemistry are optically inspected. • Extremely lean ammonia flames assisted by plasma achieve NO x emissions below 100 ppm. Aiming at the potential development of ammonia as a carbon-free renewable fuel, this work investigates the flammability and NO x emission of swirling ammonia/air flames and utilizes plasma to enhance ammonia combustion. First, the well-designed rapidly-mixed swirl burner can anchor compact ammonia/air flames under a wide range of flow conditions, with the current maximum heat release of approximately 4.7 kW. The flame is progressively detached from the quartz confinement tube and goes blow-off when the equivalence ratio drops below approximately 0.7–0.8. Then, to alleviate the problem of low flammability, gliding arc discharges driven by a 12.5 kHz alternating current (AC) power supply are facilitated to extend the lean blow-off margin to approximately 0.3–0.4. The localized flame kernels surrounding the discharge column are detected by high-speed photography. The planar laser-induced fluorescence (PLIF) imaging of OH radicals, optical emission spectroscopy, and NH 2 * chemiluminescence measurement are performed to interpret the intermediate chemistry. Finally, the NO x emission of the swirling ammonia/air flame is measured by a flue gas analyzer. Results show that although the AC-powered gliding arc exhibits weak global effects on the NO x reduction of burner-stabilized ammonia/air flames prevailing at higher equivalence ratios (e.g. , φ > 0.75), leaner flames stabilized by discharges can achieve NO x emissions below 100 ppm due to the thermal DeNO x mechanism. [ABSTRACT FROM AUTHOR]

• Aluminum particles are burning in controlled gas temperature and oxygen fractions. • A simple and compact 2D pyrometer method is developed to measure the average projected particle temperature. • The pyrometry is experimentally validated and agrees well with numerical results. • The burning of 125 µm particles shows aluminum sputtering and flame asymmetry. This work seeks to investigate the ignition and burning of micron-sized aluminum particles using nonintrusive temperature measurements and high-speed photography. First, the detected emission spectra were used to deduce the particle temperature according to Planck's laws, and the emissivity dependence on the wavelength was determined. Second, the ratio pyrometer method using a Nikon digital camera was developed to specify the two-dimensional temperature profile. These two methods were preliminarily validated through a B-type thermocouple of known temperature. Further, aluminum particles with controlled sizes of approximately 45 and 125 µm were injected as a well-dispersed stream or discrete single particles, respectively, into the hydrocarbon combustion exhaust with controlled gas temperature and compositions. The temperature evolutions of 45 µm aluminum particles derived from the camera pyrometer are in reasonable agreement with the numerical results predicted by a previously developed model. Regarding 125 µm particles, the temperature contour shows a sharp temperature increase and flame expansion during ignition. It can be attributed to the transition from surface reaction to more vigorous combustion in the vapor phase, which was visualized by a high-speed camera equipped with a long-distance microscopic lens. In this work, the camera pyrometer has demonstrated the capability of measuring the average projected particle temperature and characterizing the combustion process of micron-sized aluminum particles, with promising simplicity and economy. [ABSTRACT FROM AUTHOR]

• This paper conducts the assessment of CO2 storage capacity of offshore saline aquifers including Bohai Bay Basin in northern China, also Beibu Gulf Basin and Yinggehai Basin in southern China. • Different assessment methodologies are applied, and the mechanism and results are compared to analyze the applicability. • Results show that the CSLF and CO2BLOCK methods take into the account the storage mechanisms such as geological structure storage, residual gas storage and dissolution storage, the results seem more reasonable. Also different storage time interval could results in various capacity potential under safe injection in CO2BLOCK method. • In summary, the CO2 storage potential of Bohai Bay Basin, Beibu Gulf Basin, and Yinggehai Basin are 39.98, 53.22, and 13.37 Gt, respectively. Saline Aquifer CO 2 Storage (SACS) has become a vitally important technology for mitigating climate change brought on by anthropogenic and fossil fuel emissions. Application of SACS projects in offshore saline aquifers in China is quite promising, and the CO 2 storage technical and economic potential are considerable. However, the storage capacities achieved from different analytical and numerical methods varies a lot from each other since the main factors taken into account are variable. In this paper, different methodologies are applied to conduct the assessment of CO 2 storage capacity of offshore saline aquifers including Bohai Bay Basin in northern China, also Beibu Gulf Basin and Yinggehai Basin in southern China. Results show that the storage capacity obtained from European Commission's method is much less than that determined by the other three methods (i.e., USDOE, CSLF and CO2BLOCK method) since it mainly effected by the area of the saline aquifers. Since both of the CSLF and CO2BLOCK methods take into the account the storage mechanisms such as geological structure storage, residual gas storage and dissolution storage, the results seem more reasonable. In addition, the CO2BLOCK method considers the formation stability during injection as well, which is more in accordance with the reality. In summary, the CO 2 storage potential of Bohai Bay Basin, Beibu Gulf Basin, and Yinggehai Basin are 39.98, 53.22, and 13.37 Gt, respectively. This further verifies the great potential of industrial-scale pilot and demonstration CO 2 storage projects in offshore deep saline aquifers in China. [ABSTRACT FROM AUTHOR]

• The flame and flow dynamics under air flow pulsations are resolved by performing validated LES and simultaneous OH-PLIF/PIV. • Temporal variations of stretch rate and heat release rate can be used as a criterion for flame extinction/reignition. • A novel decoupled simulation which integrates the plasma source terms and the CFD model is developed. • Thermal and kinetic effects of microsecond repetitively pulsed discharge on combustion are quantitatively interpreted. This paper intensively investigates the inlet pulsation-induced extinction of a premixed swirl flame (PSF) and its plasma-assisted stabilization using the microsecond repetitively pulsed (MRP) discharge. A well-designed low-frequency flow pulsation is applied to the air feedline for the mimicking of transient operations/disturbances in practical engines, which exhibits significant deterioration on the lean blowout (LBO) limit. The MRP discharge is utilized to improve the stability of perturbed flames. It extends the LBO limit at a proper time delay between the air flow pulsation and the discharge, with discharge power less than 1% of the combustion power. Further, the validated large-eddy simulations (LES) and the simultaneous OH planar laser-induced fluorescence/particle imaging velocimetry (OH-PLIF/PIV) measurements are performed to capture the unsteady evolution of flames approaching lean blowout. The nonlinear flame response to the flow pulsation quantitatively reveals the phase difference between the maximum local stretch rates (κ max) and volumetric heat release rates (q ̇ c). A combined effect of the excessive stretch and the reduction of heat release due to flow pulsation can be used to interpret the flame extinction. Finally, a novel LES-ZDPlasKin combined approach, which decouples the discharge and combustion processes, is dexterously developed to simulate plasma-assisted combustion behaviors. The reignition and stabilization due to the plasma effects are well reproduced in the predictive model, pronouncing the indispensable and synergistic thermal and kinetic effects of the MRP discharge on flame stabilization. [ABSTRACT FROM AUTHOR]

• Hydrocarbon generation by alkaline lacustrine source rocks involve multiple sources and stages. • Shale oil accumulation in saline lacustrine strata is continuous. • Saline lacustrine source rocks host integrated conventional and unconventional hydrocarbon resources. • Sequential extraction can constrain the entire history of hydrocarbon generation of source rock under geological conditions. Saline lacustrine fine-grained rocks are important hydrocarbon source rocks and host large shale oil accumulations worldwide. However, the specific process and mechanism of hydrocarbon generation and accumulation in such rocks are not clear. Sequential extraction is a method to chemically separate different hydrocarbon fractions in sedimentary rocks, commonly as free, adsorbed and retained hydrocarbons, and thus can theoretically record the entire process of hydrocarbon generation and accumulation. To test this hypothesis, here sequential extraction was carried out on source rock samples with varying maturities from the alkaline lacustrine strata of the Lower Permian Fengcheng Formation, Mahu Sag, Junggar Basin, northwest China. The 17β-ethylandrostane/C 29 -sterane ααα20R and tricyclic terpane/pentacyclic triterpane ratios vary with maturity. In contrast, some biomarker parameters are not significantly affected by thermal maturity, including pristane/phytane, β-carotane index (β-carotane/main peak n -alkane), sterane/hopane, 7-+8-methyl index (7-+8-monomethyl heptadecane/main peak n -alkane), and C 28 /C 29 regular sterane values, and can thus be used for oil–source rock correlations. The low-maturity source rocks have undergone one stage of hydrocarbon generation and associated shale oil accumulation, whereas source rocks with relatively high maturity have experienced multi-stage hydrocarbon generation and associated shale oil accumulation. In the early stages, cyanobacteria were the main bioprecursor to hydrocarbons and, with increasing maturity, Dunaliella gradually became the more important bioprecursor. Hydrocarbon generation by these alkaline lacustrine source rocks involved multiple sources and stages, which accounts for the abundant shale oil resources in the Mahu Sag with one-billion-ton reserves. This might be general for saline lacustrine source rocks worldwide, which can generate both conventional and unconventional hydrocarbons in large scales. Compared with conventional thermal modeling to constrain the generation history of hydrocarbon source rocks, a unique advantage of sequential extraction is its ability to characterize the entire history of hydrocarbon generation under geological conditions. [ABSTRACT FROM AUTHOR]

Among the techniques to mitigate CO 2 emissions into atmosphere, CO 2 geological storage is the only option for gigaton removal of CO 2. This study performs a pilot test of CO 2 -EOR and storage in a tight reservoir of Baibao oilfield, located at the Ordos Basin of China. Two scenarios: CO 2 injection through two newly drilled wells and total nine wells, with two CO 2 injection schemes: continuous injection (CI) and water alternative gas (WAG) injection, are considered. Simulation results show that both CO 2 injection schemes can substantially increase oil production, compared to the current waterflooding. To be more specific, WAG, in contrast to CI, increases oil production by 7.9% and 16.2% for the two- and nine-injection well scenarios, respectively. Yet, as for CO 2 storage, WAG, compared with CI, finally leads to a decrease of stored CO 2 by 9.6% and 15%, for the two- and nine-CO 2 injection well scenarios, respectively. From the aspect of CO 2 utilization efficiency, net CO 2 utilization ratio of WAG is smaller than the one from CI regardless of the number of CO 2 injection well. Besides, for the two- and nine-injection well scenarios, maximum net utilization ratios are achieved after 7–8 years' and 4–5 years' injections, respectively. The sensitive analyses reveal that the impact of CO 2 injection rate of WAG on total oil production is more significant than the water injection in WAG. Water injection rate in WAG negatively affects the total CO 2 storage and CO 2 net utilization ratio whereas the higher CO 2 injection rate dramatically increases the total CO 2 storage. Overall, this study not only sheds light on achieving double-win goal via CO 2 injection, but also can be a valuable reference for other CO 2 -EOR and storage pilot tests in tight reservoirs. • A pilot test of CO 2 -EOR and storage in a tight oil reservoir is established. • Continuous CO 2 injection and water-alternative-gas injection both can substantially increase oil production. • Continuous CO 2 injection results in higher CO 2 storage whereas water-alternative-gas injection gives rise to larger oil production. • Major injection parameters affecting oil production and CO 2 storage are screened. [ABSTRACT FROM AUTHOR]

• A 2D/3D model was developed to simulate composite propellant burning under wide pressure range. • Flame structure and standoff distance for multiple flame were examined in detail. • Heat flux determined by AP monopropellant, premixed binder and primary diffusion flames controls the burning rate. • Effect of primary diffusion flame on the burning rate alleviates with increasing AP particle size. • Relationship between cone-angle of final diffusion flame and flow velocity was elucidated. This study developed a combustion model for ammonium perchlorate (AP)/hydroxyl–terminated polybutadiene (HTPB) composite propellant to capture the flame structure and elucidate the mechanism governing burning rate at different pressures, AP sizes and surface morphologies. A numerical model was proposed to characterize gas domain by solving Navier-Stokes equations of reacting flow field with 3-step and 12-species global kinetics; and the condensed domain was coupled by considering interfacial energy balance. The present model was validated with experimental results of both pure AP and AP/HTPB combustion, in which the mean absolute percentage error of burning rate for all cases was less than 5%. The standoff distances of AP monopropellant, premixed binder and primary diffusion flames were determined as 14.2, 12.1 and 25.8 μm at 2 MPa, respectively, reducing with pressure. The front and height of final diffusion flame were determined by axially varied radial gradient of temperature and its height was obtained as 152 μm at 2 MPa, which rises as the pressure or AP particle size increases. The increase of burning rate with pressure is attributed to the raise of surface heat flux dominated by standoff distances of AP monopropellant, premixed binder and primary diffusion flames, in which the effect of primary diffusion flame enhances as the AP size decreases resulting from enlarged lateral diffusion of species. Finally, the effects of protrusive, recessive AP surfaces and their combination with planar AP surface on the flow and flame properties were examined. [ABSTRACT FROM AUTHOR]