Carbon dioxide (CO2) photodissociation dynamics in the low-energy region of the 1Δu ← X1Σg+ absorption band (149.55-160.55 nm) is investigated using velocity map imaging with state-selective detection of O(1D) photoproducts from the dominant CO(X1Σ+) + O(1D) channel. Total kinetic energy release (TKER) spectra and photofragment angular distributions are obtained at a series of discrete photolysis wavelengths corresponding to structured features in the vacuum ultraviolet absorption band. The TKER spectra exhibit rich structures that can be assigned to rovibrational state distributions of the CO(X1Σ+) co-products, including contributions from both rotationally hot vibrationally cold and vibrationally excited channels extending to the energetic limits. A small but significant contribution from vibrationally excited CO2 present in the molecular beam is identified through the appearance of above-threshold TKER features and additional spectral intensity in specific kinetic energy regions. The presence of vibrationally excited CO2 in the molecular beam enables access to additional features in the TKER spectra that are less apparent under colder beam conditions. The partitioning of excess vibrational energy into translational, vibrational and rotational degrees of freedom is found to vary with photolysis wavelength, accompanied by systematic changes in the anisotropy parameters of selected CO(v, low j) channels. These observations are consistent with wavelength-dependent changes in the underlying dissociation dynamics and suggest that initial vibrational excitation of the parent molecule could influence the energy disposal and angular distributions of the photofragments. The results provide a comprehensive picture of CO2 photodissociation dynamics in the low-energy VUV region and offer new insight into the vibronic structure and state-dependent behavior of the 1Δu absorption band.

The pre-combustion chamber burner coupled with radial air staging is a combustion technology that reconciles flame stability with NOx reduction. For this technology, this paper combines cold-state gas-particle flow experiments with pilot-scale hot-state experiments to comprehensively study the effect of key operating parameters (secondary air ratio, RSA) on the flow field, combustion behavior and NOx emission. When RSA ranges from 0.1 to 0.83, there are central and annular recirculation areas (CRA & ARA) in the pre-combustion chamber (PCC). When RSA is 0.10, weaker entrainment of primary air by the secondary jets shifts the obvious CRA onset downstream (on the plane of x/d = 1.8), compared with the cases where RSA ranges from 0.22 to 0.83 (on the plane of x/d = 1.0). RSA increases from 0.10 to 0.83, which is conducive to the rotation and diffusion of the airflow. When RSA ranges from 0.11 to 0.67, stable ignition is maintained, with temperatures in the furnace exceeding 1473 K. As RSA increases from 0.11 to 0.67, the PCC center temperature increases; the CO concentration at furnace center shows a decreasing trend, while the NOx concentration shows an opposite trend; the pulverized coal burnout climbs from 98.4% to 99.8%, while the NOx emission concentration rises from 59 mg/m3 to 364 mg/m3. Taking all factors into account, the comprehensive performance is superior when the RSA is 0.25, with a pulverized coal burnout rate of 99.4% and a NOx concentration of 209 mg/m3 (O2 = 9%). These findings provide experimental foundations and engineering suggestions for pulverized coal boilers in terms of stable combustion and pollutant control.

Based on an MW-scale coal-NH3 co-combustion pilot facility, this study systematically investigated the effects of four inner-to-outer secondary air ratios (RSA, defined as the mass flow ratio of inner secondary air to outer secondary air) on the in-furnace temperature field, key species distributions (O2, CO, NH3, NOx), and final emissions. The results indicate that RSA is a critical parameter controlling the atmosphere structure in the main combustion zone and the fuel nitrogen conversion pathways. As RSA increased from 0.11 to 0.57, the preferential oxygen consumption by pulverized coal was enhanced, and the main combustion zone gradually shifted from a relatively oxidizing to a strongly reducing environment, effectively suppressing fuel nitrogen conversion to NOx. Under the RSA = 0.57 condition, NOx emissions decreased to 432 mg/m3, approximately 14.5% lower than those at RSA = 0.11, while the tail-end CO concentration remained low at 14 ppm, and the combustible content in fly ash was only 5.01% (achieving a burnout rate of 99.53%). These findings demonstrate that appropriately configuring the radial secondary air ratio can balance "high combustion efficiency" and "ultra-low emissions" in coal-NH3 co-combustion, providing an experimental basis for the optimized design of coal-NH3 burners.

Abstract To address the issues of severe noise pollution and high carbon emissions associated with turbine engine propulsion systems used in previous generations of supersonic technology, this study proposes the ammonia decomposition turbine-less SOFC/supersonic jet engine hybrid system (NH3 SOFC/SJE system). The proposed design aims to achieve supersonic cruising, transoceanic flight, and zero-carbon emissions, offering a sustainable solution for next-generation supersonic propulsion systems. The results indicate that as the pressure ratio increases, specific thrust continues to rise, while the fuel consumption rate initially decreases and then increases. The optimal pressure ratio is found to lie between 15.1 and 19.8. Higher fuel utilization efficiency contributes to the improved performance of the hybrid system. When the ammonia decomposition temperature is around 900 K, both the fuel economy and propulsion performance of the hybrid system are effectively met. The hybrid system achieves the most economical cruising state at an altitude of 20 km and a Mach number of 1.8. In this optimal cruising state, the Cost per unit distance of the conventional turbojet engine is 39.9% higher, while that of the H2 SOFC/SJE system is 6.03% higher compared to the proposed system. In summary, ammonia, as a zero-carbon fuel, offers significant advantages for supersonic flight.

The gasification agent's flow rate has a significant impact on gasification performance. However, current research has only examined the effect of material balance on syngas composition. No studies have investigated the impact of gasification agent flow rate on mixing characteristics and flow field in the gasifier. To enhance the gasification performance of the gasifier, this study employs two cold-flow experiments. A 0.75: 1 single-phase flow experiment shows that at a gasification agent flow rate of 75%, mixing between the airflows is dominated by flow diffusion, resulting in a low mixing degree. At 100% flow rate, axial mixing is intense. At 125% flow rate, the central flow must overcome shear resistance to maintain motion, resulting in weakened diffusion capacity. A 1: 2.5 air-particle two-phase flow experiment shows that in the upper chamber, an increase in gasifier agent flow rate can significantly enhance the tangential average velocity and improve the gas-solid two-phase mixing degree. In the lower chamber, under the three flow rates, the particles all move downward along the wall with the rotating gas flow, and the formed slag layer can protect the membrane wall from ablation.

To realize the feasibility of using low-carbon powdered solid waste as an alternative fuel for large-scale co-firing in power plant boilers, and solve issues of poor stable combustion, incomplete burnout, and high NOx emissions, this study developed a novel swirl burner with a strong stable combustion precombustion chamber for ultra-low-carbon coal gasification fine slag (CGFS) combustion, and built a 0.5 MW precombustion chamber swirl combustion pilot system. Combustion performance and NOx emission characteristics of CGFS-bituminous coal blends at different ratios were studied, with numerical simulation verifying the swirl combustion-tangential combustion coupling scheme. Pilot tests showed that as CGFS ratio rose, furnace outlet NOx first dropped from 355 mg/m3 to 107 mg/m3 then rose to 147 mg/m3, while burnout rate fell from 97% to 92.7%. Numerical simulations indicated 98% burnout for all blends, low NOx emissions under all conditions, and consistent furnace combustion state with pilot tests. Considered fuel burnout and NOx emissions, the 0-100% blending ratio maintained ignition and stable combustion. This technology enables efficient combustion of ultra-low-volatile CGFS without auxiliary fuel; the precombustion chamber swirl-tangential combustion scheme suits full-size power plant boilers. The study confirms the feasibility of using the swirl burner for large-scale co-firing of powdered solid waste in power plant boilers, supporting solid waste resource utilization, power plant energy conservation, carbon reduction, and cost control.

Pressurized gasification plays a significant role in clean coal technology, but the by-product, coal gasification fine ash (CGFA), exhibits a year-on-year increase in emission volumes, which severely constrains the healthy development of the coal gasification industry. In this study, CGFA with ultra-low calorific value and ultra-low volatile content was utilized as a substitute fuel for coal and was consumed via chamber combustion. By constructing a MW-scale swirl combustion system, the combustion characteristics of pressurized coal gasification fine ash (calorific value: 8660.01 kJ/kg, volatile matter content: 3.52%) blended with bituminous coal at different blending ratios (pressurized CGFA blending ratio: 0-40%) were investigated. Comprehensive measurements were conducted on in-furnace parameters such as temperature, flue gas composition, and fly ash burnout rate. Stable ignition and efficient burnout of pressurized CGFA were achieved. At a 30% blending ratio, the furnace flame remained bright and stable, with the maximum temperature in the main combustion zone exceeding 1300 degrees C. The burnout rate reached as high as 99.24%, while NOx emissions at the furnace outlet were measured at 290.93 mg/m3, a 32.19% decrease from the 429.03 mg/m3 observed in pure coal combustion.

The vacuum ultraviolet absorption spectrum of gas phase hydrogen iodide molecules displays numerous sharp features attributable to excitations to (often perturbed) predissociating levels of Rydberg states belonging to series converging to the lowest ionisation limit(s). The present work explores and discusses the fate of photoexcited HI molecules formed when exciting on more than 140 such parent resonances in the wavelength range of 126-141 nm, via measurements of the branching into dissociation channels yielding an H atom together with ground (I) and spin-orbit excited (I*) products, and the recoil anisotropies of these respective products. It also serves to highlight the very high, and very tightly defined, velocities (and kinetic energies) of the H atom products, which can attain v ∼ 36 km s-1 (E ∼ 647 ± 3 kJ mol-1 (6.70 ± 0.03 eV)), with a measured velocity spread Δv/v ∼ 0.25%, which can be expected to find application in future dynamical studies of atom-molecule collisions and atom-surface scattering experiments.

This study systematically investigated the co-combustion characteristics of coal and NH3 at different ammonia blending ratios (0%, 5%, 15%, and 20%) on a MW-scale pilot platform. The effects on in-furnace temperature fields, key species distributions, and burnout behavior were analyzed to reveal the synergistic influence of ammonia addition on combustion and pollutant formation. A staged combustion strategy was implemented to achieve stable combustion and coordinated emission control. Results show that a 5% NH3 blending ratio weakened the initial coal ignition and combustion intensity, while promoting NOx formation. With increasing NH3 proportion, the main combustion zone gradually shifted toward a strongly reducing atmosphere. NOx emissions exhibited a non-monotonic trend, increasing first and then decreasing with higher NH3 blending ratios. Under the 15% NH3 condition, NOx concentration was 489 mg/m3, NH3 slip remained below 78 ppm, CO was only 9 ppm, and burnout reached 99.39%. The 15% NH3 condition achieved a balance between emission reduction, combustion stability, and engineering feasibility, providing experimental evidence for low-carbon combustion and low-NOx synergistic control.

This study evaluates how the primary-zone excess air ratio (alpha) dictates in-furnace combustion dynamics and NOx emissions during coal-ammonia (NH3) co-firing. Results show that under all tested alpha conditions, the primary combustion zone exhibits a radially stratified structure, with a fuel-rich core surrounded by an oxygen-rich outer annulus. The oxidation-reduction conditions in the core, however, change significantly with alpha. Decreasing the primary-zone excess air ratio (alpha) from 0.97 to 0.70 shifts the core atmosphere from mildly oxidizing to strongly reducing. This causes substantial accumulation of CO and NH3 both axially and radially, while elongating the flame downstream. NO(x )emissions decrease monotonically from 735 mg/m(3) (alpha = 0.97, NH3 slip 69 ppm), 663 mg/m(3) (alpha = 0.88, 45 ppm), 489 mg/m(3) (alpha = 0.80, 78 ppm), to 350 mg/m(3) (alpha = 0.70, 342 ppm), all with >98.4% coal burnout; alpha = 0.80-0.88 provides optimal balance. These findings indicate that the excess air ratio in the primary combustion zone is a key parameter for controlling NOx formation during coal-NH3 co-firing.

The pre-combustion chamber burner (PCCB) is widely used in coal-fired boilers, and the swirl blade angle (gamma) significantly affects the gas-particle flow field in the confined pre-combustion chamber (PCC), especially during the initial stage of coal combustion under in-furnace air-staging conditions. However, existing research on the effect of gamma on the burner outlet flow field mainly focuses on free-expansion conditions, with a lack of systematic studies examining the influence of gamma on the gas-particle flow characteristics in the confined structure of the PCC, which is critical for optimizing PCCBs. Therefore, in this work, the phase doppler anemometry (PDA) is utilized to study the influence of gamma (40 degrees, 50 degrees, 60 degrees, 70 degrees) in secondary air (SA) on the gas-particle flow behaviors within the PCC. The results indicate the presence of central and interlayer recirculation zones within the PCC. As gamma increases from 40 degrees to 70 degrees, the entrainment effect of SA on primary air (PA) decreases in the early flow stage but increases in the later flow stage. The gas-particle flow develops on section from x/d = 0.3 to x/d = 1.8 in the PCC, the decay rate of the maximum tangential mean velocity is below 25%, markedly lower than the 40%-80% observed in swirl burners without a PCC. In addition, the particles entering the PCC move towards the wall under the centrifugal force of the swirling SA, resulting in a high normalized particle volume flux on x/d = 1.3-1.8 section near the wall. In order to mitigate the slagging risk of the PCC wall, in the design of the PPCB, the length of the PCC (in terms of x/d) should not exceed 1.0. Comprehensive analysis suggests that gamma = 60 degrees represents the optimal case.

The co-biased burner arrangement has the advantages of generating swirling flow and enhancing gas-solid mixing. The deviation of the burner deflection angle from the design value is a common occurrence, yet relevant research on it is uncommon. This study investigates the changes in gas-solid two-phase flow and flame deflection in the gasifier when the burner deflection angle deviates from the design value, using Particle Dynamic Analyzer (PDA) experiments and numerical simulation. When the burner deflection angle is smaller than the design value, the swirling flow in the gasifier tilts. When the deflection angles of A1 and A2 are 0 degrees, 4 degrees, the temperature at the furnace top reaches above 1900 degrees C. When the burner deflection angle is larger than the design value, the carbon conversion rate reaches the highest at 85%, but the swirling flow expands, and the hightemperature zone is close to the wall. The results explore the typical characteristics and potential hazards of burner flame deviation, providing a reference for the optimal operation of entrained-flow gasifiers.

To meet the refrigeration requirements for space exploration technology in supercritical helium temperature between 6–10 K, this paper focuses on the helium Joule–Thomson cryocooler (JTC). The refrigeration temperature and specific cooling capacity of a supercritical helium JTC are influenced by various complex factors. An enthalpy flow model for the supercritical helium throttling cycle is established to systematically investigate the effects of high pressure, low pressure, precooling temperature, heat transfer efficiency, and specific heat load under representative operating conditions on both the refrigeration temperature and the specific cooling capacity of the cryocooler. To further validate the model, a supercritical helium throttling experimental platform has been established and corresponding experiments have been conducted. The experimental data are consistent with the calculated values of the enthalpy flow model, with a maximum deviation of approximately 1.2

In this study, high-temperature co-firing experiments using coal gasification fine ash (CGFA) and bituminous coal were conducted in a high-temperature drop tube furnace (DTF) to explore the effects of different temperatures, excess air coefficients, and blending ratios on combustion performance. The experimental results showed that increases in temperature and excess air coefficients were beneficial to the combustion of CGFA; moreover, cofiring CGFA effectively reduced NOx emissions. The burnout rate and NOx emission results indicated that the optimal blending ratio range of CGFA was 30%-50%. A technical scheme for coupling pre-chamber swirl combustion with tangential combustion was further proposed, and numerical simulations were conducted on the pre-chamber swirl burner arranged in a tangentially fired boiler. The effect of different primary air temperatures on the velocity distribution, temperature, and atmosphere concentration in the furnace was explored under 30% CGFA co-firing. The results indicated that low nitrogen combustion and efficient CGFA burnout can be achieved at a primary air temperature of 150 degrees C. This study proposes a new technical solution for the large-scale co-firing of CGFA in power plant boilers.

To address the escalating electrical power demands, extend endurance, and simultaneously improve fuel economy for unmanned aerial vehicles (UAVs), this study proposes and comprehensively evaluates a novel solid oxide fuel cell hybrid turbofan system. This system innovatively integrates NaBH4/Al coupled hydrolysis for on-board hydrogen generation and features an integrated water circulation system. Thermodynamic models for the engine, reactor, and fuel cell were developed and validated, enabling detailed performance and exergy analyses. Comparative evaluations with a conventional turbofan engine revealed the proposed hybrid system's superior performance, particularly the version incorporating an anode recirculation pump. For instance, at a 35 % electric power fraction, this system achieved a 28.22 % reduction in specific fuel consumption, a 16.95 % increase in thermal efficiency, and a 12.57 % increase in overall efficiency compared to a conventional turbofan. Parametric analyses on fuel cell system, engine, and flight parameters identified optimal operating conditions, with exergy analysis pinpointing the engine combustion chamber as the primary source of irreversible losses. This novel hybrid propulsion system offers a compelling solution for achieving long-endurance, high-efficiency UAV operations with reduced fuel consumption, providing critical technical support for future aviation electrification.

Coal gasification fine ash is an industrial solid waste with high carbon content that cannot be directly utilized. To address the large-scale disposal of coal gasification fine ash, this paper proposes a combustion technology route and develops a novel burner equipped with a pre-combustion chamber and a radial staged combustion arrangement, thereby enhancing combustion stability and reducing NOx emissions. A MW-scale pilot-scale combustion test rig is constructed to conduct combustion tests on CGFA, SC, and BC. The flue gas temperature and composition are measured at different positions in the combustion system, as well as the flue gas composition and burnout rate at the furnace outlet. The results indicate that the new PCC burner can achieve stable ignition and combustion for all three fuels tested, with temperature rise rates exceeding 2000 degrees C/m and the peak furnace temperature reaching above 1300 degrees C. When burning CGFA with ultra-low volatile content, the burnout rate reaches 92.68%, achieving excellent burnout performance and meeting the high-efficiency decarbonization target of CGFA. The NOx emissions at the furnace outlet are only 147.16 mg/m3 (@6%O2). The test results indicate that the combustion of CGFA by chamber combustion method proposed in this paper is feasible.

This review comprehensively analyzes the synergistic development of alternative fuels and propulsion systems for achieving carbon–neutral aviation. It details the current status, comparative advantages, and challenges of key technologies: lithium battery-powered electric propulsion, Sustainable Aviation Fuels (SAF), hydrogen fuel cells, hydrogen gas turbines, and hydrogen-based carriers like ammonia and methanol. The paper highlights hydrogen-based fuels as viable near- to mid-term transition solutions due to their favorable volumetric energy density and simpler logistics compared to gaseous hydrogen. A significant contribution is the introduction of a composite system-level energy density metric, which jointly evaluates fuel energy and propulsion system specific power/efficiency, providing a more holistic framework for assessing next-generation aircraft performance. Major identified barriers encompass high fuel costs, underdeveloped supply infrastructure, and complex fuel-power system integration. The review concludes that successful decarbonization necessitates parallel development across multiple technology pathways, strengthened interdisciplinary collaboration, and robust, adaptive policy support. A phased commercialization roadmap is proposed, foreseeing battery-electric power for short-range eVTOLs first, followed by hydrogen fuel cells and hydrogen-based fuels for regional aviation by the mid-2030s, with SAF and hydrogen turbines scaling up for long-haul operations toward 2050.

This paper proposes a Platinum (Pt)-Ti (Titanium) thin-film heating method for de-fluxing Single Flux Quantum (SFQ) circuits, addressing key limitations of conventional hotspot-based approaches, such as nonuniform temperature distribution, low thermal efficiency, and delayed response. A comprehensive analysis and performance evaluation of different heating methods are conducted to investigate the impact of heat methods on Josephson junction (JJ) de-fluxing. Superconducting computers, which use SFQ logic for highspeed operation and ultra-low power consumption, suffer from logical errors caused by trapped magnetic flux in JJs. To de-flux an SFQ circuit after logic errors, the JJs must be heated above the threshold temperature and then cooled in the absence of a magnetic field. Our studies show that heating the JJs to 22 K or above reliably removes trapped flux. Pt thin-film resistive materials, known for their rapid thermal response and controllable diffusion, offer a more efficient solution for de-fluxing and thermal control in SFQ circuits. The thin-film method demonstrates superior performance, achieving a more uniform temperature distribution (standard deviation of 0.02 K), faster thermal response within 1.2 s, and an optimal heating power of 1500 mW with an effective heating duration of 2 s. These results demonstrate a reliable and efficient de-fluxing method, essential for restoring functionality and ensuring logical error recovery in large-scale superconducting computers.

The entrained-flow gasifier for fine slag can be applied for large-scale industrial use of gasification fine slag. The gas-solid two-phase flow characteristics of a 10000 Nm3/h fine slag entrained-flow gasifier were studied using a cold flow experiment system and a PDA (Phase Doppler Anemometry) measurement system to improve the gasifier's gasification performance. The flow field in the gasifier was compared in detail with various burner bias angles. The results reveal that when the burner is arranged biased in the same direction, there is an obvious central tangent circle in the velocity field of the horizontal section where the burner is positioned. When the burner's bias angle is 2°, the tangential area is the smallest, the upward movement of particles is the greatest, the particle updraft rate is up to 0.47, and the turbulence intensity is more than when the bias angle is 4° or 6°. When the bias angle is 2° in the vertical section of the upper gasifier, the downward-moving particle velocity is the largest, the downward-moving particle concentration is the greatest, the airflow swirl intensity is the smallest, and the swirl is the weakest, which is not conducive to the formation of slag layer on the membrane wall. When the bias angle is 6° in the vertical section of the lower gasifier, the tangential velocity of the airflow is the greatest, the swirl intensity is the highest, and the axial velocity is greater than the axial velocity of 4° and 2°. The particles' residence time in the gasifier gets shorter, which hinders the complete reaction of the fine slag.

This study aimed to enhance the flexibility capability of thermal power units to address challenges in integrating renewable energy into the grid, especially stable combustion at low loads in faulty coal-fired boilers. A new improved swirl burner was developed and successfully applied to a 700 MW boiler. This paper enhanced testing conditions and focused on varying boiler loads. Gas-solid flow characteristics under different boiler loads were acquired through a cold experiment. Industrial measurements were conducted on-site, revealing gas temperature distribution. The burner could form an annular recirculation zone at 15%-20 % rated loads, demonstrating its potential for stable combustion at ultra-low loads. Boiler load significantly affected velocity distribution in primary and secondary air. The reflux ratio increased as the load decreased. At low loads, there was increased negative particle volume flux and recirculation. Load had little effect on the burner central temperature but correlated more strongly with the secondary air area temperature. Coal ignition distance was approximately 2.0 m in the center and near the exit in the secondary air region. Temperature differences in the secondary air area were minimal between 522 MW and 645 MW but relatively higher at 444 MW. Cold-state experiment results effectively explained hot-state phenomena.