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An Investigation on the Formation and flow Characteristics of Nature Gas Hydrates at Different Loop Inclination Angles

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SSRN 2022年

作者： Liu, Ni Wang, Cheng Meng, Fei Yang, Liang Liu, Daoping School of Energy and Power Engineering The University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China

One of the major issues in flow assurance includes pipeline plugging due to gas hydrate formation and deposition,which makes it imperative to look for appropriate hydrate control strategies. In this study, a high-pressure visual flow loop was used to analyze the influence of different inclination angles (0°–4°) on the formation, flow, morphology evolution, deposition process, and mechanism of hydrates. The macro-parametric data, including pressure, temperature, velocity, hydrate induction time and hydrate volume fraction, were compared and analyzed. Results showed that the hydration reaction rate of downslope section is slightly faster than that of upslope section in inclined section. Although the amount of hydrate finally formed is the same, the hydrate in the downslope section is more dense. While the loop inclination angle had little effect on the amount of hydrate formation, with the increase of inclination angle, the induction time tends to decrease and the hydration reaction time will be longer overall. At 1° inclination angle, the induction time was the shortest and the hydration reaction time was the longest. The deposition process of the horizontal pipe is divided into four stages, in which large hydrate particles in the liquid phase are evenly distributed throughout the pipeline, forming a hydrate moving bed. The hydrate deposition process of the inclined pipe is also divided into four stages. Among them, the large hydrate particles in the liquid phase are concentrated on the upper wall of the pipeline, which causes the density of the upper part of the pipeline to be much higher than that of the lower part, forming a hydrate-fixed *** results of this study can deliver theoretical support to ensure the safe transportation of gas hydrate slurries. © 2022, The Authors. All rights reserved.

关键词： Gas hydrates

EXPERIMENTAL INVESTIGATION ON THE REFLOODING IN A 5×5 ROD BUNDLE 29

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EXPERIMENTAL INVESTIGATION ON THE REFLOODING IN A 5×5 ROD B...

2022 29th International Conference on Nuclear engineering, ICONE 2022

作者： Liu, Weihua Yuan, Hongsheng Wu, Pan Wang, Ting Shan, Jianqiang School of Nuclear Science and Technology Xi'an Jiaotong University No. 28 Xianning West Road Shaanxi Xi'an China China Nuclear Power Technology Research Institute Co. Ltd No.1001 Shangbu Middle Road Futian District Guangdong Shenzhen518026 China The State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an China

ISBN: (纸本)9780791886410

In the current study, a series of reflood tests with uniformly power input have been carried out at the 5×5 rod bundle film boiling test facility of the Nuclear Safety and Operation laboratory(NUSOL) of Xi'an Jiaotong University and the experimental results have been analyzed in detail. The effect of several parameters, including subcooling of coolant (10K to 75K), coolant flow rate (2.5m/s to 10.0m/s) and input wall linear power density (7 W/cm to 13 W/cm) on quench front of reflooding patterns have been studied. It is observed that the quench front during reflood stage of the rod bundle channel is sensitive to above parameters. Increase in input wall linear power density, and decrease in flow rate and subcooling of coolant results in delayed reflooding. The temperature, heat flux and heat transfer coefficient on the rod surface have been got via the self-development Reflooding Experimental Data Analysis (REDA) code. The data is not only useful for the development of theoretical models for film boiling heat transfer, two-phase void fraction, pressure drop, and rod bundle reflooding prediction, but also can be used as a benchmark data base for evaluating the analysis code of Loss of Coolant Accident (LOCA) in reactor and the design of the residual heat removal system. Copyright © 2022 by ASME.

关键词： Coolants

Low-energy and accelerated hydrogen release from MgH2–5 wt% NaTiOxH catalyzed hydrogen storage reactor by graphite responsive microwave

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Journal of Magnesium and Alloys 2025年

作者： Wang, Bofei Wu, Zhen Liu, Honghao Yang, Fusheng Zhang, Zaoxiao Yao, Jing Li, Qian Cao, Hujun Li, Bo State Key Laboratory of Fluorine & Nitrogen Chemicals School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow for Power Engineering Xi'an Jiaotong University Xi'an710049 China National Engineering Research Center for Magnesium Alloys Chongqing University Chongqing400044 China Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian116023 China Faculty of Engineering Electrical Energy Management Group University of Bristol BristolBS8 1QU United Kingdom

Owing to high thermal stability and large reaction enthalpy, MgH2 has high reaction temperatures and sluggish reaction kinetics in the dehydrogenation process, which consumes lots of energy. To achieve hydrogen release with low energy consumption, accelerated reaction rate, and high heating uniformity, this paper proposes a novel method of graphite responsive microwave-assisted thermal management with NaTiOxH catalyst. A multi-physics model of the 5 wt% NaTiOxH catalyzed MgH2 reactor integrated with a microwave generator is developed to investigate the reaction, heat and mass transfer process of hydrogen release. It is found that the graphite responsive microwave heating method could improve the temperature uniformity of reaction bed, reduce the energy consumption by at least 10.71% and save the hydrogen release time by 53.49% compared with the traditional electric heating method. Moreover, the hydrogen desorption thermodynamics could be improved with the increase of microwave power. The hydrogen release time is shortened by 19.55% with the increase of 20 W microwave power. Meanwhile, it is also concluded that the microwave excitation frequency of 2.1 GHz and the graphite content of 2 wt% have better heating performance. Therefore, it can be verified that the graphite responsive microwave heating helps to low-energy and accelerated hydrogen release from MgH2 hydrogen storage reactor. © 2025

关键词： Reaction rates

Numerical Study on Phase-Change Thermal Storage for Thermal Management of Intermittent High-power Devices

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SSRN 2022年

作者： Chen, Liang Fan, Jing Zhang, Pingtao Xiao, Runfeng Si, Yansong Chen, Shuangtao Hou, Yu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Key Laboratory of Icing and Anti/De-Icing China Aerodynamics Research and Development Center Mianyang621000 China

Latent heat thermal energy storage (LHTES) is an effective approach for thermal management of intermittent high-power output electronics. The limited heat absorption power due to the low conductivity of phase change material is an urgent problem for LHTES. This paper investigates a finned tube heat exchanger with dual-side phase change heat transfer, i.e., LHTES of paraffin RT60 on the fin side and condensation of low-pressure water on the tube side. The proposed model couples the three-dimension enthalpy-porosity model on the fin side with the one-dimension homogeneous flow model on the tube side, yielding the solutions of the dynamic process of the LHTES. The heat-charging power and storage effectiveness of LHTES with single-phase and two-phase heat transfer fluids (HTFs) on the tube side are compared and discussed under different condensation pressures and mass flow rates. Heat transfer on both the fin and tube sides are critical for the LHTES performance, and the use of two-phase HTF on the tube side can enhance the heat-charging power by 210.5% and raise the storage effectiveness by 33.5%. The storage effectiveness decreases with the increase of condensation pressure while the mass flux of tube-side HTF does not have an obvious effect on the storage effectiveness. The maximum power density (1.3 kW/L) of LHTES is obtained when the condensing pressure is 90 kPa and the mass flow rate is 0.045 kg/s. It is indicated that dual-side phase change heat transfer to storage energy can provide a compact and efficient thermal management solution for intermittent high-power devices. © 2022, The Authors. All rights reserved.

关键词： Temperature control

Efficient One-Step Electrochemical Synthesis of Ammonia-Hydrogen Fuel for Clean Energy Applications

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SSRN 2025年

作者： Yang, Zhongmei Wang, Xiaoyang Mu, Xiaojiang Hong, Congjie Miao, Lei Novel Battery Materials Research Center of Engineering Technology State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures School of Physical Science and Technology Guangxi University Nanning530004 China State Key Laboratory of Multiphase Flows in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Ammonia-hydrogen fuel, recognized as a quintessential zero-carbon green energy source, presents significant challenges in storage and transportation due to the inherent safety risks associated with hydrogen fuel handling. Leveraging ammonia's potential as an efficient hydrogen storage medium, we focus on developing a novel technology for on-site ammonia decomposition to produce hydrogen under ambient conditions. Here, we employ a straightforward electrochemical process to catalytically decompose ammonia into hydrogen and nitrogen at standard temperature and pressure, with ammonia in its gaseous form directly volatilized from an aqueous ammonia solution. A CeO2@NiCu₃/NF electrocatalyst capable of efficient ammonia decomposition at an impressively low potential (1.27 V vs. RHE) was synthesized. This catalyst demonstrated a Tafel slope of 41.5 mV dec-1, significantly improving electrolysis efficiency. It also exhibited excellent stability during 21 hours of continuous operation. Density Functional Theory (DFT) analysis revealed that the unique composite structure of CeO2 and NiCu3 features a d-band position similar to platinum, optimizing the adsorption-desorption balance of ammonia. Furthermore, the impact of ammonia on the combustion characteristics of hydrogen under different cracking ratios was investigated from an application perspective. Combustion kinetics simulations were performed to evaluate the effects of ammonia on the ignition delay time (IDT) and laminar flame speed (LFS) of hydrogen. The results indicate that the presence of small amounts of NH3 has a negligible effect on the ignition delay time of hydrogen but significantly reduces its laminar flame *** study provides a valuable experimental foundation for advancing the practical utilization of hydrogen as a sustainable fuel while addressing the challenges associated with ammonia-hydrogen energy systems. © 2025, The Authors. All rights reserved.

关键词： Ammonia

Waste Tire-Derived Graphene Modified Carbon as Anodes for Sodium-Ion Batteries

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SSRN 2024年

作者： Zhou, Ziyi Wang, Silang Wen, Bo Xiao, Jiyuan Yang, Guorui Ding, Shujiang School of Chemistry Engineering Research Center of Energy Storage Materials and Devices Ministry of Education "Four Joint Subjects One Union" School Enterprise Joint Research Center for Power Battery Recycling & Circulation Utilization Technology Xi’an Jiaotong University Xi’an710049 China Xi’an Key Laboratory of Solid Waste Recycling and Resource Recovery State Key Laboratory of Multiphase Flow in Power Engineering Department of Environmental Science and Engineering Xi’an Jiaotong University Xi’an710049 China

The rational disposal of waste tires poses a ubiquitous challenge globally. Pyrolytic carbon black, a solid by-product produced through pyrolysis, has great application prospects. Carbon-based materials are regard as the most potential commercial anode materials for sodium-ion batteries (SIBs) ， which features cheap, environmentally friendly, and low reaction potential. In this study, three-dimensional vertical graphene composite (TCBp@VGSs) was synthesized from waste tires. The graphene with higher defectiveness offers an increased number of active sites for Na+, while the vertically aligned graphene facilitates rapid electron transfer. As a result, the TCBp@VGSs electrode demonstrates the ability to maintain a reversible capacity of 252.7 mA h g-1 after 100 cycles at a current density of 0.2 A g-1. Furthermore, it exhibits a sustained rate performance of 105.4 mA h g-1 at a current density of 5 A g-1. Moreover, even after 1900 cycles at a current density of 1 A g-1, a reversible capacity of 171.5 mA h g-1 is retained, showcasing good stability and a significantly higher capacity compared to TCBp-1100. This study introduces novel approaches for the high-value utilization of solid-phase by-products from waste tires, offering certain economic benefits, and contributes fresh insights into the advancement of SIBs anodes. © 2024, The Authors. All rights reserved.

关键词： Graphene

Numerical Study on the Local Heat Transfer Characteristic of Supercritical Co2 in Semicircular/Circular Channel Under Cooling Condition

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SSRN 2022年

作者： Zhong, Shao-Geng Ren, Yan Wu, Weidong Yang, Ying-Ying Yang, Qi-Guo School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China

A mathematic-physical model was established to explore the local heat transfer characteristics of supercritical CO2 in semicircular and circular channels under cooling condition, which was applied in the field of supercritical CO2 Brayton cycle. The numerical method was validated by the experimental data with the average error of 3.79%, meeting the accuracy requirement. And the operation pressure, cooling heat flux, inlet velocity and hydraulic diameter were 8~9 MPa, 10~14 kW·m-2, 1.2~5 m·s-1 and 1~2 mm, respectively. The results showed that the local heat transfer coefficient of supercritical CO2 would increase at first and then decrease along the flow direction regardless of the semicircular channel and circular channel, and the peak value gradually decreased with increasing operation pressure and disappeared when the inlet velocity exceeded 3 m·s-1. Meanwhile, the heat transfer performance of the semicircular channel was weaker than that of the circular channel due to the influence of the corner area and the buoyant effect, and the latter played a dominant role. For the horizontal flow, the buoyant effect was increased, while the heat transfer was decreased with increasing hydraulic diameter of the semicircular channel. Besides, the influence of different flow directions on the heat transfer performance of the semicircular channel (about 6.2%) was greater than that of the circular channel (about 0.48%, and could be ignored). Finally, the heat transfer correlation of the supercritical CO2 cooling process in the horizontal semicircular channel was modified by considering the influence of the dimensionless buoyancy effect and hydraulic diameter, and the prediction errors of 90% correlation calculation results were within ±14% after the modification. These results will provide some theoretical guidance on the design and optimization of the cooler for the supercritical CO2 Brayton cycle system. © 2022, The Authors. All rights reserved.

关键词： Heat flux

Under-Deposit Corrosion Behavior and Dynamic Deliquescence Properties of Ammonium Salts Covered on Pipelines and Components in a Crude Oil Distillation Column: Experimental and Theoretical Studies

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SSRN 2022年

作者： Li, Ruidong Chen, Jukai Wang, Yueshe State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi'An710049 China School of Chemical Engineering & Technology China University of Mining and Technology Xuzhou221116 China

Electrochemical experiments based on the interdigital electrodes of SAE 1020 steel and atomic simulation were performed to investigate the under-deposit corrosion behavior and dynamic deliquescence properties of ammonium salts. In-situ electrochemical measurements demonstrate that the deliquescence of ammonium salts affects the evolution of the interface, and the surface characterization results proved that the critical state of moisture absorption leads to the most severe corrosion. Additional ab initio molecular dynamics simulations suggest that the H transport chain impacted by the hydrolysis of NH4+ leads to a variation in the charge state of the system, which may triggering corrosion. © 2022, The Authors. All rights reserved.

关键词： Steel corrosion

Development of Polyamine/Alkanolamine-Based Hypergolics with Hydrogen Peroxide: A New Route to N-Methylimidazole with Mdea as a Promising Green Fuel

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SSRN 2023年

作者： Mota, Fábio A.S. Liu, Mingyang Mohsen, Abrar A.A. Yao, Xiaoxin Mai, Zhaoming Tang, Chenglong State Key Laboratory of Multiphase Flows in Power Engineering Xi’an Jiaotong University Shanxi Xi’an710049 China SP Santo Andre09210-580 Brazil

A novel non-ionic liquid fuel based on a mixture of N-methylimidazole (MIm) and N-methyldiethanolamine (MDEA) called PAHyp 2 which reacts hypergolically with hydrogen peroxide is presented in this work. To study the hypergolic behaviors, a drop test setup able of capturing simultaneous high-speed schlieren, infrared and visible imaging were used. While infrared images capture the temperature history of the ignition process, schlieren images offer advantages of capturing the pressure waves as well as providing better visualization of the morphological description of the liquid dynamics. PAHyp 2 with hydrogen peroxide (98%) has specific impulse 6% lower than hydrazine-based fuels but because of its higher density it requires smaller propellant tanks for a given mission. In order to meet the requirements of good chemical stability and low viscosity of less than 30 cP, the proportion of MIm should range between 40 and 50% (or 60 to 50% of MDEA) and the amount of catalyst should be no more than 3 wt%. FTIR spectra showed no chemical degradation. By adding 3 wt% catalyst, the shortest ignition delay time of 8.8 ms was recorded. Based on these preliminary results, we believe that just like the other polyamiane/akanolamine-based fuels recently reported by our group, this new recipe is also a promising candidate and as such should be further studied. © 2023, The Authors. All rights reserved.

关键词： Hydrogen peroxide