bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of Ignition Assistant on Combustion of Cetane 30 and 35 Jet-Fuel Blends in a Compression-Ignition Engine at Moderate Load and Speed
Authors: Miganakallu Niranjan , Stafford Jacob , Amezcua Eri , Kim Kenneth S. , Kweon Chol-Bum M. , Rothamer David A. 
Published: November 2022

Abstract
This study investigates the use of a commercial-off-the-shelf (COTS) ceramic glow-plug to assist ignition of jet fuel blends with cetane numbers of 30 and 35, below the minimum cetane number of 40 for #2 diesel. Experiments were carried out on a single-cylinder compression-ignition engine operating at 1200 RPM for single and dual-injection (pilot + main) timing sweeps. The COTS glow-plug, termed the ignition assistant, was operated at varying input power levels between 0 and 70 W (stock maximum power input is 30 W) at each SOI. Results demonstrate that the use of an ignition assistant at the higher input powers (50 and 70 W) enables operation over a wider range of SOI timings where more advanced times are limited by high pressure-rise rates and more retarded times are limited by rapidly increasing coefficient of variation of gross indicated mean effective pressure. Use of the ignition assistant enables stable combustion at later injection timings increasing the operable range of SOI timings. For the CN 30 fuel, at earlier injection timings, pressure traces and heat release analysis demonstrated the advancement of start of combustion and combustion phasing with the ignition assistant on. At retarded injection timings where combustion would not otherwise occur completely for the CN 30 fuel, operating the ignition assistant at the higher powers enabled combustion phasing to be advanced and combustion to be stabilized at conditions where, with the ignition assistant off, misfire (flameout) would occur. Furthermore, the ignition assistant enabled combustion phasing to follow an approximately linear response with respect to SOI timing over a wider range of SOI times.
Combustion characteristics of F24 compared to Jet A in a Common Rail Direct Injection Research Compression Ignition Engine
Authors: Soloiu Valentin , Smith Richard Collins , Weaver Amanda , Parker Lily , Brock Dillan , Rowell Aidan , Ilie Marcel 
Published: November 2022

Abstract
Research was conducted to determine combustion characteristics such as: ignition delay (ID), combustion delay (CD), combustion phasing (CA 50), combustion duration, derived cetane number (DCN) and ringing intensity (RI) of F24, for its compatibility in Common Rail Direct Injection (CRDI) compression ignition (CI) engine. The first part of this study is investigating the performance of Jet-A, F24, and ultra-low sulfur diesel #2 (ULSD) using a constant volume combustion chamber (CVCC) followed by experiments in a fired CRDI research engine. Investigations of the spray atomization and droplet size distribution of the neat fuels were conducted with a Malvern Mie scattering He-Ne laser. It was found that the average Sauter Mean Diameter (SMD) for Jet-A and F24 are similar, with both fuels SMD droplet range between 25–29 micrometers. Meanwhile, ULSD was found to have a larger SMD particle size in the range of 34–40 micrometers. It was observed during the study, utilizing the CVCC, that the ID and CD for neat ULSD and Jet-A are nearly identical while the combustion of F24 is delayed. F24 was found to have longer durations of both ID and CD by approx. 0.5 ms. This results in a lower DCN for the fuel of 43.5, whereas ULSD and Jet-A have DCNs of 45 and 47 respectively. The peak AHRR for ULSD and Jet-A are nearly identical, whereas F24 has a peak magnitude of approx. 20% lower than ULSD and Jet-A. It was found that both aviation fuels had significantly fewer ringing events occurring after peak high temperature heat release (HTHR), a trend also observed in the CRDI research engine. Neat F24, Jet-A and ULSD were researched in the experimental engine at the same thermodynamic parameters: 5 bar indicated mean effective pressure (IMEP), 50°C (supercharged and EGR) inlet air temperature, 1500 RPM, start of injection (SOI) 16°BTDC, and 800 bar of fuel rail injection pressure as the baseline parameters in order to observe their ignition behavior, low temperature heat release, combustion phasing, and combustion duration. It was found that the ignition delay of F24 and Jet-A was greater than ULSD, approx. 5% for both aviation fuels. This ignition delay also affected the combustion phasing, or CA 50, of the aviation fuels. The CA 50 of the aviation fuels was delayed by approx. 2% compared to ULSD. Jet-A had a nearly identical combustion duration compared to ULSD, however F24 had an extended combustion duration which was approx. 3% longer than that of ULSD and Jet-A. It was discovered with the accumulations of these delays in ID, CD, CA50, that the RI of the aviation fuels were reduced. F24 was discovered to have more delays, and the RI correlates with these results having a 70% reduction in RI compared to ULSD.
Exploring the Benefits of Oxidative Coupling of Methane on Natural Gas Engine Efficiency Through One-Dimensional Simulation
Authors: Swift Evan , Wadkar Chaitanya , Lee Hyewon , Singh Satbir , Northrop William F. 
Published: November 2022

Abstract
Natural gas (NG), mainly composed of methane, is extremely resistant to autoignition. High efficiency premixed compression ignition (CI) combustion modes are therefore difficult to achieve in NG engines. One potential method for expanding the range of compression ignition operation in NG engines is to pretreat the fuel such that it becomes more reactive. This paper presents results from one-dimensional simulations of a medium duty multi-cylinder natural gas engine partially fueled by products from oxidative coupling of methane (OCM), a catalytic process by which methane is converted to C2 hydrocarbons like ethane and ethylene. First, the results of OCM reactor three-dimensional CFD simulations are presented to define the resulting product species distribution over a range of residence time. Using the reactor results, a one-dimensional model of an engine is implemented with and without OCM products to illustrate efficiency gains possible by operating in a compression ignition mode. Results of the modeling show that brake thermal efficiency improves by 1 to 7% with OCM-enabled CI combustion compared to spark ignition combustion of natural gas alone. The results also show that since the OCM reactor is exothermic, part of the incoming natural gas heating value is converted to sensible enthalpy. The OCM products therefore must be used to preheat the intake charge, thus avoiding an overall brake thermal efficiency (BTE) penalty. Overall, this study finds that OCM products have the potential to increase BTE of NG engines by allowing them to operate in premixed CI modes. Future work must look to improve OCM catalyst durability and reactor turndown ratio to provide a reliable high reactivity fuel stream for NG engines.
A Scoping Study on the Use of Direct Quantification of Fault Tree Using Monte Carlo Simulation in Seismic Probabilistic Risk Assessments
Authors: Kubo Kotaro , Fujiwara Keita , Tanaka Yoichi , Hakuta Yuto , Arake Daisuke , Uchiyama Tomoaki , Muramatsu Ken 
Published: November 2022

Abstract
After the Fukushima Daiichi Nuclear Power Plant accident, the importance of conducting probabilistic risk assessments (PRAs) of external events, especially seismic activities and tsunamis, was recognized. The Japan Atomic Energy Agency has been developing a computational methodology for seismic PRA, called the direct quantification of fault tree using Monte Carlo simulation (DQFM). When appropriate correlation matrices are available for seismic responses and capacities of components, the DQFM makes it possible to consider the effect of correlated failures of components connected through AND and/or OR gates in fault trees, which is practically difficult when methods using analytical solutions or multidimensional numerical integrations are used to obtain minimal cut set probabilities. The usefulness of DQFM has already been demonstrated. Nevertheless, a reduction of the computational time of DQFM would allow the large number of analyses required in PRAs conducted by regulators and/or operators. We therefore performed scoping calculations using three different approaches, namely quasi-Monte Carlo sampling, importance sampling, and parallel computing, to improve calculation efficiency. These were applied when calculating the conditional core damage probability of a simplified PRA model of a pressurized water reactor, using the DQFM method. The results indicated that the quasi-Monte Carlo sampling works well at assumed medium and high ground motion levels, the importance sampling is suitable for assumed low ground motion level, and that the parallel computing enables practical uncertainty and importance analyses. The combined implementation of these improvements in a PRA code is expected to provide a significant acceleration of computation and offers the prospect of practical use of DQFM in risk-informed decision-making.
Numerical investigation of particle erosion characteristics in supercritical carbon dioxide in elbow pipe channels
Authors: Xu Peng , Zhou Tao , Fu Zhongguang , Chen Juan 
Published: November 2022

Abstract
The erosion of pipe walls by particle in supercritical carbon dioxide (SCO2) has a significant impact on the safe operation of the reactor, therefore, a simulation study of the wall erosion pattern of particulate matter within the SCO2 in the bent pipe channel was carried out. The research results show that SCO2 is extruded to the outer wall side under the action of centrifugal force. At the same time, two symmetrical secondary flows are formed in the elbow area, in the range of angle 60°–75°, the flow line is the most intensive and the secondary flow phenomenon is the most obvious; the erosion of particulate matter on the pipe is mainly concentrated in the outer side of the elbow area; with the increase of mass flow velocity, the erosion rate of particulate matter on the wall surface gradually increases. And the effect of increasing mass flow velocity on the erosion rate is nearly linear; the increase of particle diameter will lead to the first increase and then decrease of erosion; when the density of particles increases, the erosion rate of particles on the wall decreases, but the effect is low.
Numerical Analysis of Heat Transfer Enhancement With Spiral Tube in the Passive Containment System
Authors: Chen Kai , Wang Ruiqi , Huang Chonghai , Qi Xiao , Wang Xiaoyan 
Published: November 2022

Abstract
In this paper, the condensation heat transfer characteristics of light tubes and spiral tube tubes are studied by numerical analysis. The condensation characteristics of vertical spiral tube containing non-condensing gas vapor were explored, and the distribution of steam velocity, pressure and temperature near the wall of the heat transfer tube was analyzed. The enhanced heat transfer method of non-condensing gas vapor was obtained, which provided a theoretical basis for the enhanced heat transfer of steam condensation. The results show that the spiral tube can increase the heat exchange performance. The spiral can effectively reduce the thickness of the liquid film, which can impressively enhance the heat transfer performance.
Investigation of the Fuel Element Damage Monitoring Technology in HTGRs and PWRs
Authors: Nie Rui , Wang Yu , Xie Feng , Qing Shan , Cao Jianzhu 
Published: November 2022

Abstract
Understanding the performance of fuel elements, particularly defective ones, in the reactor core quickly and accurately is essential as most radioactive nuclides are produced in the fuel elements and released into the primary circuit. Radioactivity in the primary circuit may result in potential radiation hazards to the maintenance workers and the environment near the nuclear power plant. Therefore, fuel element damage monitoring technology has received wide attention in the field of nuclear fission reactors. Few reviews focus on fuel element damage monitoring technology to facilitate the development of high-temperature gas-cooled reactors (HTGRs). In this study, we investigated the state of fuel element damage monitoring technology in HTGRs and pressurized water reactors (PWRs), summarized their characteristics and parameters, and compared their advantages and disadvantages. The radioactive source terms in HTGRs and PWRs were listed, and the typical nuclides in the primary circuit adopted for the fuel element damage monitoring were illustrated. This study can provide a good reference for developing fuel element damage monitoring technology in HTGRs in the future.
Discussion on Optimization of Protection Effect of Shielding Doors in High Level Waste Treatment Facilities
Authors: Shen Jingyi , Zhang Liying , Wang Bingheng , Gao Guiling 
Published: November 2022

Abstract
Due to the special nature of the radiation sources involved (high radioactivity and high penetration) in high discharge waste treatment facilities, several shielding doors are installed in the facilities to ensure staff safety. In the analysis of the radiation protection design of shielding doors, it is found that the type of radiation source, the relative position of the radiation source and the door, and the structure of the door all have an impact on the radiation shielding effect. In this paper, the shielding door of a hot room in a high discharge waste treatment facility is used as the research object, and the dose rate outside the shielding door is analyzed with the characteristics of radiation sources and their different locations, and with respect to the existing shielding door structure. The analysis results show that, under the premise of meeting the shielding requirements, when the radiation emitted by the source has a certain angle of incidence relative to the shielding door, the dose rate at a specific location outside the door will be significantly increased due to the scattering leakage of the door slit and the effect of the oblique penetration of the radiation. In addition, the characteristics of the radiation source, such as the type of nuclide, and the geometry can also influence the safety design of the shielded door. Therefore, in order to optimize the protection effect of shielded doors, considering that the characteristics of radiation sources are generally difficult to optimize, this paper proposes several solutions from two perspectives: door slit scattering and overlap length, and combining other influencing factors from different aspects. The optimization effects of each solution are also compared, and the corresponding adaptation sites are also outlined through their respective advantages and disadvantages. Through the analysis and research of this paper, the safety and effectiveness of the shielding door is improved, the safety of personnel is guaranteed, and the foundation for the future design of the shield door is laid.
Simulation Research on the New Electrode Structure of Ionization Chamber Detector
Authors: Chang Jiahao , Wang Zhentao , Xu Shuo 
Published: November 2022

Abstract
The gas ionization chamber can be used in the examination of the irradiated fuel assembly and online measurement of steel sheet thickness. Response time is an important parameter of gas ionization chamber detectors, which will affect the clarity of radiation imaging. Previous results show that in the ionization chamber of the traditional structure, the electric field intensity is relatively low in some areas, which will affect the response time of the gas detector. By modifying the structure of the electrode, the areas of the weak electric field can be reduced or even eliminated. In this paper, we propose a new electrode structure, and two software tools are used in this work. Solidworks is used to establish ionization chamber models with different electrode structures. The finite element analysis software Simcenter MagNet is adopted to obtain the electric field distribution. The results show that the area of the weak electric field inside the ionization chamber of the new electrode structure is significantly reduced. In addition, the average electric field strength inside the gas ionization chamber detector with the new electrode structure is also improved. Theoretical calculation results show that the drift time of ions is reduced by about 0.690ms. Therefore, the development of the new electrode structure can effectively reduce the response time of the detector.
Experimental Study and Intelligent Prediction on Pressure Fluctuation of Accumulator Under Ocean Conditions
Authors: Wei Tianyi , Xie Guanhui , Li Dongyang , Tan Sichao , Du Yangyang , Li Zhongyi , Wang Yuan 
Published: November 2022

Abstract
Liquid sloshing will occur in liquid storage tanks such as accumulator of floating nuclear power plant (FNPP) subjected to additional inertial forces under motion conditions. The study carried out measurement experiments based on the 6-DOF platform to study the sloshing characteristics and pressure variation rule of the accumulator. The results show that surging will induce many kinds of nonlinear free surface sloshing forms, it can be seen that the law of pressure variation is mainly dominated by natural frequency and excitation frequency based on time and frequency domain analysis. Then the study combines the automatic encoder and extreme learning machine to build the deep extreme learning machine (DELM) network to predict the pressure in time series. Based on the phase space reconstruction of the time sequence, the pressure results of the next time are output after the last 15 pressure data are input. The prediction results show that the DELM model has fast speed and high precision and the predicted value is in good agreement with the experimental data. So this study can provide a reference for the pressure monitoring and the artificial intelligence application of FNPP.
Sensitivity and Uncertainty Analysis of Molten Corium-Concrete Interaction (MCCI) for ALWR During Severe Accident
Authors: Wu Zijie , Chen Peng , Zhao Xinhao , Guo Chao , Zhan Dekui , Xia Shaoxiong 
Published: November 2022

Abstract
Molten corium-concrete interaction is an important phenomenon in the late phase of severe accident, threatening the integrity of containment and might causing potential large release of radioactivity. A sensitivity and uncertainty analysis of MCCI under severe accident of a 1000 MW advanced light water reactor (ALWR) was performed with ASTEC (MEDICIS) [1], a lumped parametric integral severe accident code developed by IRSN. Several representative phenomena were screened out referenced by EURSAFE severe accident Phenomena Identification and Ranking Table (PIRT) [2], including debris bed formation, layer configuration, heat sources, and convective heat transfer correlation. Related input parameters, sensitivity coefficients, and modeling options in ASTEC code were selected, such as convective correlations, layer stratifications, initial layer compositions, and the potential ranges of these parameters were identified. A simple sampling method was used to analyze the independent effect of each parameter/model. Key parameters were chosen to evaluate the impact of sensitivity parameters to the MCCI process. A large break loss of coolant accident scenario, where in-vessel melt retention is invalid is simulated as an initial event. The results emphasize the importance of layer configuration and fission product partition. However, it should be emphasized that analysis results may be quite uncertain due to the limitation of the physical models and the adequacy or validity of the selected range of input variables.
Flow Mixing Characteristics in Double Loop Reactor Pressure Vessel Under Accident Conditions
Authors: Xie Guanhui , Li Runcheng , Wei Tianyi , Lin Zhikang , Li Dongyang , Tan Sichao 
Published: November 2022

Abstract
In case of core emergency cooling safety injection, the boron containing coolant injected externally and dilution water mass will be mixed in the pressure vessel. The uneven mixing of boron containing coolant and dilution water mass may lead to the return of the core to criticality. Therefore, it is of great significance to accurately measure the boron concentration distribution in the pressure vessel and study the mechanism affecting the mixing process for the safe operation of the reactor. In this paper, combined with the structural characteristics of HPR1000 pressure vessel, a visual experimental device is built through proportional modeling design, and the flow mixing process of diluted water mass, safety injection solution and coolant in the pressure vessel under double loop operation is obtained by using plane laser-induced fluorescence technology, the effects of different Reynolds numbers on the diffusion of boric acid were experimentally studied. The experimental results show that under the condition of double loop, the two inlets divide the circumferential direction into good arc and bad arc. The velocity distribution of fluid flowing through the bad arc is more uniform, while the vertical flow of fluid flowing through the good arc is uneven; The fluid flows downward rapidly after the intersection on the inferior arc side, and the intersection height is positively correlated with the cold pipe flow, while the fluid on both sides shows obvious mixing after the intersection on the superior arc side; Clear water mass cannot be avoided at the core inlet, but increasing the cold pipe flow and safety injection flow can reduce the time of clear water mass flowing through the core.
Study on Aerosol Growth and Deposition Properties Affected by Steam Condensation
Authors: Xia Zhaoyang , Zhou Zhiwei 
Published: November 2022

Abstract
The MELCOR 2.1 computer code has been used to simulate the large-scale aerosol behavior experiment in the Containment System Test Facility (CSTF) vessel. The test LA2 of the Light Water Aerosol Containment Experiments (LACE) was designed to simulate the containment conditions and aerosol behaviors in the high-steam-concentration environment under a postulated severe accident. In this study, the Aerosol Condensation model’s (ACD) and Hygroscopic Model’s (HM) ability of the aerosol behavior prediction has been evaluated by the simulation of LA2 based on MELCOR 2.1 code. It has been found that the size distribution and depletion rate of dry aerosols are affected by the mass of water aerosol. The different masses of water aerosol in ACD and HM models are due to the different relative humidity calculated by these two models. The simulation models with different control volumes setup were evaluated to study the effect of water aerosol mass on aerosol depletion rate. The results show that higher water aerosol mass results are calculated and better airborne aerosol masses are predicted under the multi-control volume models. Based on this research①, it can be concluded that good results of aerosol deposition in the vessel are severely affected by the accuracy of water aerosol mass. The improvement of water aerosol mass results by the MELCOR code’s simulation should be thoroughly studied.