Fuel Utilization Efficiency Research Articles

Assessing the benefit of thorium fuel in a once through molten salt reactor

This study comprehensively evaluates thorium-based fuel utilisation in the Molten Salt Reactor (MSR) with a once-through fuel cycle. It examines the whether the use of thorium is beneficial in extending the fuel cycle length of an MSR, fuel utilisation efficiency, reactor safety, and reduction of long-lived radioactive waste. To observe those parameters, this research compares the use of thorium and uranium as fertile fuel in a single-fluid, once through MSR using Uranium-233 (U-233), Uranium-235 (U-235), and Reactor Grade Plutonium (RGPu) as well as the fissile driver. MCNP radiation transport code with ENDF/B-VII.0 continuous neutron library was used to analyse the neutronic parameters and fuel burnup in a multi-refuelling scheme for a total burnup time of 8 years. The findings indicate that the utilisation of thorium in conjunction with U-233 and U-235 significantly enhances fuel consumption and improve reactor safety. Such benefits, however, did not appear in RGPu. Moreover, thorium effectively reduces the production of long-lived radioactive waste, a crucial issue in nuclear waste management. Considering technical and environmental aspects, this study offers novel insights into using thorium as a more sustainable nuclear alternative under a once through fuel cycle, within a condition of multi-refuelling cycle which is only possible in an MSR.

Enhanced sintering resistance in LaYbZr2O7 system through HfO2 doping for thermal insulation ceramic materials

AbstractThe increase in operating temperature contributes to improving the performance and fuel utilization efficiency of gas turbines. However, it also places thermal barrier coatings (TBCs) in a more demanding working environment, requiring higher sintering resistance and better mechanical properties. In the present study, HfO2 was introduced into the dual‐phase LaYbZr2O7 system as a doping oxide to form the LaYb(HfxZr1−x)2O7 system. The research concentrated on its phase composition, mechanical properties, and thermophysical properties. The results show that substituting Hf for Zr does not alter the dual‐phase structure of the system. The mutual inhibition between the two phases and the inherent material‐binding capability of Hf further reduce the grain size compared to pure LYZO. Additionally, the presence of Hf reduces the tendency of Frenkel defect formation and cation migration frequency, effectively inhibiting ion diffusion and thereby suppressing the densification and shrinkage trends of the material. The system retains relatively high hardness, fracture toughness, and low elastic modulus of the LYZO matrix, with a decrease in thermal conductivity and an increase in infrared reflectivity. These results suggest that Hf doping enhances the sintering resistance of LYZO material, making them promising for high‐temperature TBCs. Our study presents a viable approach to enhance the sintering resistance of LYZO, and this methodology can be extrapolated to other rare‐earth zirconates.

Numerical simulation of the effect of coaxial and cross-axis injection modes on pulverized coal combustion in the raceway of blast furnace tuyere

The aim of this study is to investigate the influence of the angle of the pulverized coal (PC) injection lance on the combustion characteristics of fuel in the raceway of blast furnace tuyeres. Using FLUENT software, a Euler-Lagrange three-dimensional numerical model was constructed to analyze the influence of different positions of blast furnace tuyere coal powder injection lance (coaxial and cross-axis) on key parameters such as temperature distribution, gas flow, and combustion efficiency. The results demonstrate that adjusting the angle of the injection lance significantly modifies the average and peak temperatures in the raceway, while the composition of gas components remains relatively stable. When the injection lance angle is 10°, the average temperature and peak temperature in the raceway are 2294 K and 2747 K, respectively. When the injection lance angle is 12°, the combustion efficiency of the PC reaches 80.8%. This study reveals the significant impact of the injection lance angle on the combustion process. Especially at an angle of 12°, the combustion efficiency of the blast furnace significantly improves. With coaxial injection, the combustion rate increases as the distance between the injection lance tip and the tuyere increases. This paper is instructive for the optimization of the blast furnace combustion system, which improve fuel utilization efficiency and reduce environmental emissions. This paper provides practical recommendations for adjusting blast furnace operational parameters, offering insights for achieving more efficient and environmentally friendly industrial production.

Study on fuel injection stability improvement in marine low-speed dual-fuel engines

Pressure waves within the fuel injection system exert a significant influence on the fuel injection process. This study investigated the impact of pressure waves on injection quantity stability. To quantify the influence of pressure waves on injection quantity stability, the relative standard deviation (RSD) was introduced as a metric. Through computational analysis under various operating conditions, the following results were obtained: when the target rail pressure is constant, the RSD tends to diminish as the injection quantity increases. The elevated RSDs observed during small injection quantities are predominantly attributed to the short power-on period of the solenoid valve. Subsequently, parameter optimization and structural improvements were carried out on the injector to address this problem. The results indicate that optimizing structural parameters alone has a limited effect on reducing RSD. However, by adding a block in the control chamber above the needle to improve the structural layout of the injector, the maximum RSD has been reduced from 21.08% to 4.58% under the action of pressure waves caused by fuel injection, and from 29.24% to 6.67% under the action of given random high-frequency pressure waves. The proposed improvement idea for existing injectors enhances injection stability across the entire operating condition range, thereby improving fuel utilization efficiency.

Influence of trapezoidal channel design on volume power density of ammonia-hydrogen fuel cells

Proton exchange membrane fuel cells based on ammonia decomposition gas (ammonia-hydrogen fuel cells) contain about 25% nitrogen at the anode, resulting in lower power density. In this paper, the volume power density enhancement effect of trapezoid channel with different upper edge length is studied. Research shows that the volume power density of trapezoid 0.1, 0.2, 0.4, 0.6 is increased by 53.5%, 62.0%, 81.9% and 108.3% compared with the conventional rectangular channel, respectively, and it is increased by 5.5%, 11.4%, 25.4% and 43.6% respectively, compared with the triangular channel. However, as the upper edge of the trapezoidal flow channel increases, the anode and cathode of the trapezoidal flow channel appear hydrogen hunger with a zero domain of up to 45% and the phenomenon of the horn mouth gradually moving forward respectively. Moreover, longer flow channels have lower fuel utilization efficiency, as low as 76%.

Autonomous Mission Planning for Spacecraft On-orbit Service Based on Hybrid Variant Particle Swarm Optimization

For the complex on-orbit service (OOS) mission planning problem, an improved hybrid variant particle swarm optimization (PSO) method was proposed to improve the fuel utilization efficiency of spacecraft. Firstly, considering the time and fuel constraints, a model for OOS mission planning under the scenario of multiple target spacecrafts is established. The Lambert orbit maneuver method is used and the problem is transformed into a large-scale hybrid nonlinear integer programming problem. Next, an improved hybrid variant PSO algorithm is designed to optimize the fuel performance cost, and its simple structure and lightweight operation facilitate autonomous planning, considering the limited computing power of the onboard computer. The hybrid algorithm is composed of discrete particle swarm optimization (DPSO) and PSO, so it has a strong ability to search for the optimal service sequence and orbit maneuver time simultaneously. Moreover, the adaptive and variant operators are used to improve the searching ability and avoid falling into local optimal solutions. Finally, simulation experiments show that the proposed method can quickly give optimal results, reducing fuel consumption effectively in the OOS mission and improving the OOS capability of the spacecraft.

Research on Energy Efficiency and Carbon Emission Evaluation Methods of cogeneration Technology under the Background of Carbon Neutrality

This article delves into the energy efficiency evaluation methods and carbon emission evaluation methods of cogeneration technology. In terms of energy efficiency evaluation, the concept of energy efficiency and commonly used energy efficiency indicators of cogeneration systems were introduced, such as total energy efficiency, power efficiency, thermal energy efficiency, and fuel utilization efficiency. In terms of carbon emission evaluation, the concept of carbon emissions and commonly used carbon emission indicators for cogeneration systems were analyzed, such as carbon emissions per unit of power generation, carbon emissions per unit of thermal energy, and total carbon emissions. For these evaluation methods, different implementation steps and calculation formulas were introduced in detail, and their application scenarios and advantages and disadvantages were illustrated with examples. These evaluation methods help to evaluate the performance and environmental impact of cogeneration systems, providing scientific basis for relevant decision-making.

Self-assembled Gd0.1Ce0.9O1.95-BaGd0.8La0.2Co2O6‒δ nanocomposite cathode for efficient protonic ceramic fuel cells

Protonic ceramic fuel cells (PCFCs) are characterized by a low activation energy for proton conduction and a high fuel utilization efficiency at low-to-intermediate temperatures. However, the sluggish oxygen reduction reaction kinetics on the cathodes drastically limit the power output performance of PCFCs. Herein, multiphase Gd0.1Ce0.9O1.95-BaGd0.8La0.2Co2O6‒δ (GDC-BGLC) nanocomposite cathodes are prepared by coupling self-assembly and sintering-free electrode construction methods. The nanocomposite cathode comprises mixed H+/e– conducting BGLC and O2− conducting GDC and BaCoO3 nanoparticles, and these phases are homogeneously mixed with coherent heterointerfaces. The nanocomposite cathode exhibits a significant increase in surface oxygen vacancies and three-phase boundaries, enhanced catalytic activity, and reduced activation energy for the oxygen reduction and water formation reactions. The results imply that the oxygen reduction and water formation reactions on the multiphase GDC-BGLC nanocomposite electrodes are most likely the dissociation, reduction and diffusion of oxygen species, which in turn is affected by the water vapor formed. An anode-supported single cell with the GDC-BGLC cathode exhibits a peak power density of 810 mW cm−2 at 700 °C with excellent operating stability at 650 °C for 110 h. This study provides a new strategy for the preparation of a high-performance and durable nanocomposite cathode for PCFCs.

The study of the relationship between green finance and resource efficiency in east asian economies

This empirical study, spanning 2000 to 2022 in East Asian economies, employs the Continuously-Updated and Fully Modified approach to explore determinants of fossil fuel utilization efficiency. Findings reveal a positive link between a 1% increase in green finance and a 0.16% enhancement in fossil fuel efficiency, reducing intensity. Conversely, increased inward foreign direct investment (FDI) correlates with reduced efficiency and heightened fossil fuel intensity, emphasizing the need for eco-friendly FDI strategies. A positive connection is identified between a 1% rise in green energy deployment and a 0.26% improvement in fossil fuel efficiency. However, an elevated employment ratio is associated with lower efficiency and higher fossil fuel intensity. To foster a sustainable and energy-efficient future, recommended policies include prioritizing green finance, digitalizing the green financial sector, implementing green FDI reforms, creating green job positions, and enhancing societal awareness in East Asian economies.

Process modeling and analysis of a combined heat and power system integrating solid oxide fuel cell and organic Rankine cycle for poultry litter utilization

Syngas from the gasification process of poultry litter can be utilized as the fuel in the solid oxide fuel cell for electricity production. A novel combined heat and power system, integrating solid oxide fuel cell and organic Rankine cycle, is currently proposed to achieve efficient and clean utilization of poultry litter. The effects of biomass type for co-gasification and six operational parameters on this cogeneration system are studied. Results show that the total electricity production, fuel cell power output, total heat production and primary energy utilization efficiency are 162.02 kW, 141.65 kW, 52.41 kW and 44.70%, respectively. Co-gasification of straw and poultry litter can improve the overall system performance. Low water content of poultry litter is generally preferable. The highest primary energy utilization is achieved at equivalent air ratio of around 0.26. Increasing water-carbon ratio would deteriorate the fuel cell and the overall system performance. When the operating temperature is 950 °C, the energy utilization efficiency reaches the peak value. This energy efficiency reaches the maximum value of 44.98% at fuel utilization efficiency of 0.78. This research provides a new solution for high-value utilization of the low-calorific poultry litter, to achieve the sustainable utilization of wasted energy and biomass resources.

Core nuclear design and heat transfer analysis of a megawatt-level SiC coated particle based vehicular micro reactor

As a versatile and diversified source of new energy, transportable micro reactors can offer high flexibility and the ability to provide power services even in remote areas. When utilizing coated fuel particles and supercritical carbon dioxide (S-CO2) coolant, the transportable micro reactor core achieves exceptional inherent safety and high power generation efficiency, rendering it incredibly competitive within the nuclear market. The Vehicular Micro Reactor (VMR) previously investigated is an integrated micro-reactor cooled by S-CO2, which employs TRistructural ISOtropic (TRISO) fuel particles dispersed in a conventional graphite matrix to generate 5 MW of power output. However, its drawback lies in the low fuel loading capacity. In recent year, the application of high-strength SiC materials in the field of nuclear energy has been developing continuously. In this paper, a new type of double-layered SiC coated fuel particle is designed, based on which a SiC-based Vehicular Micro Reactor (SVMR) is proposed and explored. It represents an improved design of VMR, with the main difference being its utilization of SiC as a matrix and filling by the two-layered SiC-coated fuel particle to achieve higher fuel loading than the VMR. In this paper, both the neutronic and heat transfer characteristics of the SVMR are discussed. The neutronic simulation is conducted using SCALE code based on Monte Carlo method, the module KENO IV was used to analyze the effective neutron multiplication factor (keff), and SCALE/TRITON (Transport Rigor Implemented with Time-Dependent Operation for Neutronic Depletion) coupled by 2-D radiation transport code NEWT and ORIGEN for burn-up calculation. By optimizing the assembly size and SiC-coated fuel particle size, the SVMR core achieves high fuel loading capacity and superior fuel utilization efficiency. The results of the heat transfer analysis also demonstrate that the SVMR core, which is entirely SiC-based, exhibits exceptional heat transfer capability. The excellent neutron economy and inherent safety make SVMR a more competitive micro reactor concept.

Thermodynamic analysis of an integrated reversible solid oxide fuel cell system

To improve the efficiency of reversible solid oxide cell (rSOC) systems, an rSOC thermal management system architecture is proposed, achieving integrated and efficient operation of rSOC. A 20 kW level rSOC integrated thermal management system with fuel cell and electrolysis cell modes is established using ASPEN PLUS software. The system characteristics of different system operating parameters under fuel cell and electrolysis cell modes are studied. Exergy analysis and energy analysis are conducted on the system under different operating modes, The distribution of exergy flow, the exergy loss between the system and its components, and the influence of fuel utilization on the electrical efficiency and exergy efficiency of the rSOC integrated thermal management system are obtained. The results show that compared to traditional solid oxide electrolysis cell systems, the proposed rSOC integrated thermal management system can improve the electrolysis efficiency of the system to over 70%. In addition, the exergy loss of the system and components mainly exists in heat exchanger 1 in the fuel cell mode, and mainly in the stack in the electrolysis cell mode. The system efficiency of both fuel cell and electrolysis cell modes increases with the increase in fuel utilization rate. Compared to electrolysis cell mode, the system's exergy loss in fuel cell mode is more sensitive to fuel utilization efficiency.

Electric field modulation effect and mechanism on n-alkanes fuel pyrolysis: A ReaxFF MD and DFT study

To promote the fuel utilization efficiency in the aviation and space transport, the electric field was selected as an efficiency method to modify the fuel pyrolysis rate. This work investigated the surrogate fuel component n-alkane (n-pentane, n-heptane and n-decane) pyrolysis process under the electric field. The three n-alkanes pyrolysis rate and reaction pathway were analyzed. And the reaction mechanism under the electric field was discussed by the bond cracking potential energy (PES), system thermal motion and energy. The molecular dynamics results showed the n-alkanes pyrolysis was modulated by the electric field strength, which promotion in weak electric field and inhibition in strong field. The species transformation net was complicated and selective while the conversion flux was reduced by the strong field. The field improved the molecule polarization and deformation to result in the edged carbon bond and H bond dissociation with lower energy barriers. Analyzing the molecular motion and system energy, the intermolecular distance was elongated, and interaction energy was reduced, which caused to the decrease of collision frequency under the field. The contribution of electric field to the single molecule decomposition and inhibition molecules motion worked together on the global n-alkane pyrolysis. This work supplied a theory support to the promoting fuel utilization using the electric energy.

Proposal and comprehensive analysis of power and green hydrogen production using a novel integration of flame-assisted fuel cell system and Vanadium-Chlorine cycle: An application of multi-objective optimization

Present research attempts to introduce a novel solution for dispatch-down renewable electrical power using an integration of compressed air energy storage with a pressurized flame-assisted solid oxide fuel cell. The proposed system can generate electrical power and green hydrogen using flame-assisted fuel cell and Vanadium-Chlorine thermochemical cycle. Performance of the system has been perused from 4E perspectives, and three multi-objective optimizations with different objective functions have been carried out. The effects of key parameters such as current density, fuel utilization efficiency, fuel cell operating pressure and anode recycle coefficient on the performance of the cogeneration system have been investigated for various values of fuel-rich combustion chamber’s equivalence ratio. Results reveal that the proposed system can offer both electrical power and green hydrogen with high overall efficiency. According to the optimization results, system efficiency, Levelized cost of products, and carbon dioxide emission index are obtained 93.48 %, 0.08318 $/kWh, and 0.3437 kg/kWh, respectively.

Concerns about illegal, unreported and unregulated fishing, carbon footprint, and the impact of fuel subsidy - An economic analysis of the Black Sea anchovy fishery

Among the unresolved problems of fisheries, illegal, unreported and unregulated (IUU) fishing, high carbon footprint, overfishing, and overcapitalization of the fleet are at the forefront. Supporting fishers through fuel subsidy is commonly practiced but eventually led to overcapitalization of the sector. Moreover, the reported catch weights were insufficient to meet fleet operational costs and investments, and therefore there must be some degree of IUU fishing in Black Sea. Therefore, the study examined the economic performance of the purse seiners engaged in anchovy fishery in the Black Sea coast of Turkey and Georgia. The results revealed that economic performance and revenue in the Black Sea anchovy fishery segments evaluated were sufficient to cover expenses and be profitable, even in years when the catch was insufficient. Economic analysis also showed that fuel constitutes a significant part of operational cost in all fleet segments and, in return, 0.17–0.59 tons of CO2 was produced to catch one ton of fish. Under these circumstances, the segment displaying the best fuel utilization efficiency would not survive if the remedy suggested by the UN's sustainable development goal-14, which advocates eliminating fuel subsidy to curb IUU and overfishing, were enforced. In light of the study findings, a series of remedies are suggested to discourage a trend towards IUU fishing, control the fleet's carbon footprint, and ensure sustainability. Among the proposed remedies, the removal of least effective medium-sized boats from the fleet, enforcing more efficient harvest control measures, and limiting the catch used for anchovy reduction fishery were emphasized.

Achieving complete electrooxidation of ethanol by single atomic Rh decoration of Pt nanocubes.

SignificanceDirect ethanol fuel cells are attracting growing attention as portable power sources due to their advantages such as higher mass-energy density than hydrogen and less toxicity than methanol. However, it is challenging to achieve the complete electrooxidation to generate 12 electrons per ethanol, resulting in a low fuel utilization efficiency. This manuscript reports the complete ethanol electrooxidation by engineering efficient catalysts via single-atom modification. The combined electrochemical measurements, in situ characterization, and density functional theory calculations unravel synergistic effects of single Rh atoms and Pt nanocubes and identify reaction pathways leading to the selective C-C bond cleavage to oxidize ethanol to CO2. This study provides a unique single-atom approach to tune the activity and selectivity toward complicated electrocatalytic reactions.

Study of natural uranium utilization in a heavy water moderated molten salt reactor

Heavy water moderated molten salt reactor (HWMSR) is a newly proposed molten salt reactor. It adopts heavy water as the moderator and molten salt dissolved with actinide elements as the fuel and coolant as well. These unique features endow HWMSR a high neutron economy as performed in CANDU (CANada Deuterium Uranium) pressure tube heavy water reactor and a capability to implement the processes of online refueling and reprocessing as done in the conventional MSRs, making natural uranium (NU) utilization and together with U-233 production become feasible. The obtained results in this study demonstrate that the fuel utilization efficiency of HWMSR with NU fuel cycle can achieve 1%, slightly better than that of the CANDU reactor at the same physical size and power level. Meanwhile, around 2662 kg U-233, which can start 3 new Th–U fuel cycle HWMSR cores, can be produced over 20 years’ operation by online refueling thorium and extracting Pa-233.

Ultra-clean condensing gas furnace enabled with acidic gas reduction

Natural gas furnaces are the most common space heating equipment in the U.S. residential and commercial building markets. However, current residential natural gas condensing furnaces generate substantial acidic condensate as well as significant emissions of sulfur oxides (SOx), nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbons (HC), and methane (CH4) contributing to environmental degradation of air, water, and soil. This paper describes a novel solution to reduce the environmental impact of natural gas condensing furnaces based on the technology of monolithic acidic gas reduction (AGR) catalyst for SOx trapping, NOx redox to nitrogen, and oxidation of formic acid, CO, HC, and CH4. This technology offers a new condensing natural gas furnace with both ultra-clean flue gas and neutral condensate. A prototype of the condensing gas furnace with the AGR component is demonstrated to have condensate with pH = 7, NOx emissions of 1–2 ng/J, and an annual fuel utilization efficiency (AFUE) of 96%. The AGR component and the AGR-enabled furnace were tested for long-term reliability and durability, as well as for SOx storage and regeneration activity. In addition, this paper provides new data on measurements of the specific acidic gas content in natural gas condensing furnaces.

Highly Efficient Magnetic Propulsion of NiFe Nanorod-Based Miniature Swimmers in Three Dimensions

Magnetically actuated miniature robots have attracted the attention of the scientific community over the past two decades, but the confined workspace of their manipulation system (typically a tri-axial coil or eight electromagnetic coils) and the low efficiency of propulsion have limited their utility. Here, we describe a highly efficient NiFe nanorod-based magnetic miniature swimmer that can be manipulated in 3D spaces using two pairs of coils placed in the x-y horizontal plane. In the new swimmer, the shape symmetry is broken along its body, and the asymmetry in magnetizations is introduced perpendicular to the long axis of its body simultaneously. Such a combined asymmetry design offers favorable controllability in planar magnetic fields, which relaxes the multi-axial coil requirement of the commonly used manipulation system and thus reduces the restriction on the shape and size of the workspaces. The new swimmers display efficient 3D propulsion, with a speed of over 5000 μm s-1 (∼3 body length s-1) and powerful locomotion in biological media such as raw human blood. The fuel utilization efficiency of the swimmer, defined as the ratio of the distance to the net input work in one period, was estimated to be approximately from 10-2 to 10-3 m/J, which is significantly higher than that of magnetic motors with a slender body. Moreover, to provide practical support for further potential use, we demonstrated that the swimmer is able to perform incision operations as a minimally invasive microsurgical tool. Such a swimmer actuation strategy provides a simple and efficient way for 3D manipulation of magnetic miniature robots, offering great potential for future biomedical and other applications.

Silver nanoparticles boost charge-extraction efficiency in Shewanella microbial fuel cells.

Microbial fuel cells (MFCs) can directly convert the chemical energy stored in organic matter to electricity and are of considerable interest for power generation and wastewater treatment. However, the current MFCs typically exhibit unsatisfactorily low power densities that are largely limited by the sluggish transmembrane and extracellular electron-transfer processes. Here, we report a rational strategy to boost the charge-extraction efficiency in Shewanella MFCs substantially by introducing transmembrane and outer-membrane silver nanoparticles. The resulting Shewanella-silver MFCs deliver a maximum current density of 3.85 milliamperes per square centimeter, power density of 0.66 milliwatts per square centimeter, and single-cell turnover frequency of 8.6 × 105 per second, which are all considerably higher than those of the best MFCs reported to date. Additionally, the hybrid MFCs feature an excellent fuel-utilization efficiency, with a coulombic efficiency of 81%.