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Novel Solid-state Hydrolysis Kinetics of Nabh4 for Stable and High-Capacity On-Line Hydrogen Production

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SSRN 2024年

作者： Chen, Jiawei Wu, Zhen Zheng, Jie Shi, Yu Xie, Lei Yang, Fusheng Wang, Yuqi Zhang, Zaoxiao School of Chemical Engineering Northwest University Xi’an710069 China School of Chemical Engineering and Technology Xi’an Jiaotong University Xi’an710049 China College of Chemistry and Molecular Engineering Peking University Beijing100871 China Sunan Institute for Molecular Engineering Peking University Jiangsu 215500 China State Key Laboratory of Multiphase Flow for Power Engineering Xi’an Jiaotong University Xi’an710049 China

Solid-state hydrolysis of NaBH4 could achieve high-capacity on-line hydrogen production. However, the stability of hydrogen production in the solid-state hydrolysis process has been questioned. In this paper, a novel kinetics is proposed for the solid-state hydrolysis behavior. The acceleration factor β is introduced into the traditional shrinking core model to reveal the relationship between "dissolution" and "catalytic hydrolysis" in the solid-state hydrolysis process. The comparison results show a good agreement between the model and experiment in the temperature range of 303.1.-348.1. K. Meanwhile, the kinetics conclusions and product characterization indicated that the "excessive dissolution" of NaBH4 and the "dehydration of by-products" are two important factors contributing to the uncontrolled reaction. Based on the parametric analysis and experimental verification, the optimum temperature for solid-state hydrolysis is approximately 323.1. K. Besides, the adjustment of the water intake strategy to intermittent intake reduced water consumption by 36.6%. As a result, the hydrogen release capacity could be increased to as high as 5.49 wt.% (close to the U.S. Department of Energy 2025 gravimetric hydrogen storage capacity of 5.5 wt.%), even though the weight of water is taken into account as reactant. © 2024, The Authors. All rights reserved.

关键词： Hydrolysis

Simulations on Hybrid Thermal Management of Mini-Channel Cold Plate and Pcm for Lithium-Ion Batteries Under Discharging and Thermal Runaway Conditions

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SSRN 2024年

作者： Liu, Yang Zhou, Zhifu Wu, Wei-Tao Wei, Lei Lyu, Jizu Li, Yang Liu, Xinyu Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation Ministry of Education Dalian University of Technology Dalian116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China

In this study, we compared the performance of different structures of mini-channel cold plate (MCP)- phase change material (PCM) hybrid thermal management on discharge and thermal runaway. The heat transfer structures for them can be categorized into three types: (a) uncoupled, (b) semi-coupled, and (c) fully coupled. Among these, the semi-coupled design B exhibits the best performance. Specifically, in the high rate discharge condition, the structure can control the battery temperature at 44.37°C at low coolant mass flow rate, and the temperature at 36.47°C at high mass flow rate, while the temperature difference (TD) of a single cell does not exceed 2.01.C. In a low-multiplier discharge zero-energy system, the pack temperature rise can be limited to no more than 1.°C in 35°C environment. Under external short-circuit conditions, a lower coolant mass flow rate is sufficient to keep the pack temperature at 43.22°C. Under internal short-circuit thermal runaway (TR), lower coolant mass flow rate can prolong the TR of the adjacent cell up to 521.s, and higher mass flow rate can completely inhibit the occurrence of TR. The objective of this study is to offer valuable references for the design and implementation of hybrid MCP-PCM cooling systems. © 2024, The Authors. All rights reserved.

关键词： Phase change materials

Boosting photocatalytic hydrogen production by creating isotype heterojunctions and single-atom active sites in highly-crystallized carbon nitride

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Science Bulletin 2022年第5期67卷 520-528,M0004页

作者： Shaohua Shen Jie Chen Yiqing Wang Chung-Li Dong Fanqi Meng Qinghua Zhang Yiliang Huangfu Zhi Lin Yu-Cheng Huang Yanrui Li Mingtao Li Lin Gu International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049China Department of Physics Tamkang UniversityNew Taipei City 25137TaiwanChina Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China

Carbon nitride-based photocatalysts hold an enormous potential in producing hydrogen.A strategy to simultaneously create isotype heterojunctions and active sites in highly-crystallized carbon nitride is anticipated to significantly boost the photocatalytic activity,but is yet to be ***,we find that cobalt salt added in the ionothermal synthesis can promote the phase transition of heptazine-based crystalline carbon nitride(CCN)to triazine-based poly(triazine imide)(PTI),rendering the creation of singleatom cobalt coordinated isotype CCN/PTI ***-CCN/PTI exhibits an appreciable apparent quantum yield of 20.88%at 425 nm for photocatalytic hydrogen production with a rate achieving3538μmol h^(-1.g^(-1.(λ>420 nm),which is 4.8 times that of CCN and 27.6 times that of *** high photocatalytic activity is attributed to the Type II isotype highly-crystallized CCN/PTI heterojunction for promoting charge carrier migration,and the single-atom Co sites for accelerating surface oxidation reaction.

关键词： Photocatalytic hydrogen production Single-atom cobalt Crystalline carbon nitride Poly(triazine imide) Isotype heterojunctions

Regulation Mechanism Study of Intermediate Products During Supercritical Water Gasification

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SSRN 2024年

作者： Wang, Cui Feng, Huifang Jin, Hui School of Water and Environment Chang’an University Xi’an710054 China Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of the Ministry of Education Chang’an University Xi’an710054 China Key Laboratory of Eco-hydrology and Water Security in Arid and Semi-arid Regions of Ministry of Water Resources Chang’an University Xi’an710054 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi'An710049 China

Supercritical water (SCW) gasification technology can realize efficient utilization of coal, which can convert coal to hydrogen-rich gas. But polycyclic aromatic hydrocarbons and heavy components, intermediates of supercritical water gasification, are easy to form char, preventing complete gasification of coal. In this paper, phenol is recycled to reduce the formation of these intermediates during SCW gasification, and the regulation mechanism is investigated. The results illustrate that the organics removal rate reaches about 98% with the effect of phenol. Phenol can improve the gasification performance by promoting the conversion of heavy components to lightweight components. The transient reactivity of coal in the polycondensation stage is enlarged about 50 times with phenol. The regulation mechanism of phenol on the polycondensation stage during coal gasification is investigated by analyzing the evolution of microstructure in coal. Decomposition of SCW forms hydroxyl radicals, which replaces the substituents on benzene ring, making the benzene ring dissociate into small molecules that are easy to polymerize. The interacting force between phenol and multi-rings disrupts the conjugate structure, promoting the organics with multi-ting decomposed into small molecules. © 2024, The Authors. All rights reserved.

关键词： Coal

Experimental Study on Liquid Immersion Preheating of Lithium-Ion Batteries Under Low Temperature Environment

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SSRN 2024年

作者： Bao, Jiakang Zhou, Zhifu Wu, Wei-Tao Wei, Lei Jizu, Lyu Li, Yang Huang, Heng Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China

In this paper, a single-phase immersion preheating experimental test platform is constructed to analyze the immersion preheating, the preheating performance, and the energy consumption. Immersion preheating has a major improvement on the low-temperature performance of the lithium cell, and the warming rate during preheating varies depending on the temperature (-25°C, -1.°C, -5°C, 5°C, 1.°C, 25°C) is very close to each other. The inlet temperature has a greater influence on the preheating performance than other factors, increasing the inlet temperature is favorable to rate of warming, but will increase the cell safety risks. flow rate and battery spacing increases on the rate of increase in temperature of the impact is gradually weakened, the rising inlet flows on the battery pack module temperature difference has a greater impact, the spacing increases on the battery cell and the battery pack temperature difference is gradually reduced, even so the maximum battery temperature difference is still controlled to 6℃ or less. In addition, immersion preheating has lower utilization of heat and higher energy consumption, and the preheating energy consumption at ambient temperature -25℃ has exceeded 80 % of the rated capacity of experimental battery packs. © 2024, The Authors. All rights reserved.

关键词： Energy utilization

Visualization Experiments and Piston Effect of Heat Transfer on Supercritical Carbon Dioxide in a Mini Vertical Upward flow

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SSRN 2022年

作者： Lyu, Haicai Wang, Han Bi, Qincheng Niu, Fenglei School of Nuclear Science and Engineering North China Electric Power University Beijing102206 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an710049 China

The characteristics of supercritical heat transfer and flow patterns visualization were investigated experimentally. System parameters are pressure of 7.4 ~ 8.44 MPa, the mass flux of 600 ~ 1.00 kg·m -2 ·s -1.and heat flux up to 31. kW·m -2 . The basic experimental data of heat transfer coefficient and frictional pressure drop were obtained. Local heat transfer coefficient was calculated with respect to the mass flux, heat flux and pressure. The scenario of in-tube supercritical carbon dioxide was presented by a high-resolution camera. Experimental results show that the heat transfer peak happens when the wall temperature is above the pseudo-critical temperature, and in-tube fluid is lower than the pseudo-critical temperature. Exciting phenomenon of critical opalescence is observed under the pressure of 7.4 MPa and a temperature of 31.68 ˚C. Rapid alternation of sky blue and milky white was captured in an extremely short period time, which may be related to Rayleigh scattering due to drastic density fluctuation. Piston effect of strongly uneven aggregation was formed due to the variation of thermal physical property, which can be used to exposit the mechanism of supercritical heat transfer peak near the pseudo-critical temperature. Ration of density and volumetric coefficient of expansion can be represented for the piston effect to produce the modified Jackson’s correlation, which owns the average error of -0.69% and root-mean-square error of 1..35%. © 2022, The Authors. All rights reserved.

关键词： Visualization

Steady-state Multi-Physics Coupling Analysis of Heat Pipe Cooled Reactor Core

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SSRN 2022年

作者： Zhang, Zhipeng Wang, Chenglong Guo, Kailun Tian, Wenxi Qiu, Suizheng Su, Guanghui Department of Nuclear Science and Technology Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering China

Due to the advantages of mobility, safety and universality, the heat pipe reactors have great competitiveness in many applications such as strategic defense locations, remote communities, and emergency locations. In addition, most of the heat pipe reactors are designed as solid-state reactors, which avoid the two-phase {1. problem caused by the coolant transformation and make it possible to analyze the reactor with multiple physical field coupling. In this work, a typical heat pipe reactor has been carried out a 3-D neutronic-thermal-mechanical analysis, and steady state analysis is performed by OpenMC coupled with COMSOL. Coupling calculation results show that under normal operation, the maximum temperature and thermal expansion of core is 1.38.94 K and 2.53 mm. In the steady-state coupling process, the influence of temperature parameters on physical calculation is mainly reflected in k eff and its power level, the maximum temperature drops from 1.47.26 K to 1.38.94 K, but it has little influence on power distribution. By coupling calculations, the maximum stress of the reactor is reduced by 5.78 MPa. The research results will support the subsequent development of multi-physics coupled transient analysis code for heat pipe reactors. © 2022, The Authors. All rights reserved.

关键词： Heat pipes

Numerical investigation of natural convection characteristics of a heat pipe-cooled passive residual heat removal system for molten salt reactors

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Nuclear Science and Techniques 2020年第7期31卷 25-33页

作者： Cheng-Long Wang Hao Qin Da-Lin Zhang Wen-Xi Tian Guang-Hui Su Sui-Zheng Qiu Department of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The limited availability of studies on the natural convection heat transfer characteristics of fluoride salt has hindered progress in the design of passive residual heat removal systems(PRHRS)for molten salt *** paper presents results from a numerical investigation of natural convection heat transfer characteristics of fluoride salt and heat pipes in the drain tank of a *** results are compared with experimental data,demonstrating the accuracy of the calculation *** distribution of fluoride salt and heat transfer characteristics are obtained and *** radial temperature of liquid fluoride salt in the drain tank shows a uniform distribution,while temperatures increase with increase in axial height from the bottom to the top of the drain *** addition,natural convection intensity increases with increase in height of the heat pipes in the *** between heat pipes has no obvious effect on the natural convection heat transfer *** study will contribute to the design of passive heat removal systems for advanced nuclear reactors.

关键词： passive characteristics pipes

Thermal Modulation of Radiation Fields Enhancing the Adaptability of Cpv-Hydrogen Systems to Hot Outdoor Conditions

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SSRN 2023年

作者： Zhu, Yizhou Zhang, Ting’an Geng, Jiafeng Jing, Dengwei Xi'an University of Science and Technology China Department of Chemical Engineering School of Water and Environment Chang'an University Shaanxi Xi’an710064 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

The efficiency of photovoltaic (PV) modules operating outdoors often subject to significant decrease due to high PV surface temperature under hot outdoor conditions despite of the high irradiation in this period. Meanwhile, the commercial electrolytic water splitting unit requires additional heat sources to preheat the electrolyte, which is neither economical nor energy efficient. This study introduces a proton exchange membrane (PEM) water electrolyzer system coupled with concentrated photovoltaic (CPV) and a pipe-based liquid spectral beam splitting filter acting also as an electrolyte preheater. The results of continuous experiments during local summer daytime show that the average PV surface temperature of the proposed system can be reduced by 23.5 K compared to that without spectral beam splitting filter. Moreover, the average efficiencies of photovoltaic, electrolysis and solar-to-hydrogen can be increased by 7.5%, 8.1. and 5.2%, respectively. Both simulation and experimental results confirm that our design can reduce the sensitivity of system efficiency toward weather factors, especially high-intensity summer irradiation. This work provides a promising option for application of large-scale solar hydrogen production in regions with sufficient sunlight while high outdoor temperature. © 2023, The Authors. All rights reserved.

关键词： Hydrogen production