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Characteristics of hydrogen production from steam gasification of plant-originated lignocellulosic biomass and its prospects in Vietnam

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2022年第7期47卷 4394-4425页

作者： Anh Tuan Hoang Huang, ZuoHua Nizetic, Sandro Pandey, Ashok Xuan Phuong Nguyen Luque, Rafael Ong, Hwai Chyuan Said, Zafar Tri Hieu Le Van Viet Pham HUTECH Univ Inst Engn Ho Chi Minh City Vietnam Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Univ Split FESB Rudjera Boskov 32 Split 21000 Croatia CSIR Indian Inst Toxicol Res Ctr Innovat & Translat Res Lucknow 226001 Uttar Pradesh India Ctr Energy & Environm Sustainabil Lucknow 226029 Uttar Pradesh India Ho Chi Minh City Univ Transport PATET Res Grp Ho Chi Minh City Vietnam Univ Cordoba Dept Quim Organ Campus RabanalesEdificio Marie Curie E-14014 Cordoba Spain RUDN Univ Peoples Friendship Univ Russia 6 Miklukho Maklaya Str Moscow 117198 Russia Natl Yunlin Univ Sci & Technol Future Technol Res Ctr 123 Univ RdSect 3 Touliu 64002 Yunlin Taiwan Univ Sharjah Dept Sustainable & Renewable Energy Engn POB 27272 Sharjah U Arab Emirates Natl Univ Sci & Technol NUST US Pakistan Ctr Adv Studies Energy USPCAS E Islamabad Pakistan

Demands for the decline of CO2 emissions resulted in a significant transformation of the energy systems working on carbon sources towards more sustainable, clean, and renewable characteristics. Hydrogen is emerging as a secondary energy vector with everincreasing importance in the decarbonisation progress. Indeed, hydrogen, a green and renewable energy source, could be produced from steam gasification of plant-originated lignocellulosic biomass. In this current review, key factors affect the hydrogen production yield from steam gasification of plant-originated lignocellulosic biomass, including the design of the gasifier, temperature, pressure, and steam-to-biomass ratio, steam flow rate, moisture and particle size of fed biomass, and catalysts were thoroughly analysed. Moreover, the effects of the abovementioned factors on the reduction of tar formation, which is also a key parameter towards ensuring the trouble-free operation of the reactor, were critically evaluated. More importantly, the separation of produced hydrogen from steam gasification of biomass and challenges over technological, environmental, and economic aspects of biomass gasification were also presented in detail. In addition, this paper is also profiling the prospect of Vietnam in fulfilling its hydrogen economy potential because Vietnam has vast biomass due to its tropical weather and availability of arable land, providing abundant lignocellulosic biomass with 45% of agricultural waste, 30% of firewood, and 25% of other sources. Besides, some primary factors hindering the broad application of biomass for hydrogen production were indicated. Finally, some solutions for implementing the hydrogenization strategy in Vietnam have also been discussed. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Biomass Hydrogen production Steam gasification Affecting factors Techno-economic challenges Vietnam

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Exergy analysis of the regulating measures of operational flexibility in supercritical coal-fired power plants during transient processes

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APPLIED ENERGY 2019年 253卷 113487-000页

作者： Zhao, Yongliang Liu, Ming Wang, Chaoyang Wang, Zhu Chong, Daotong Yan, Junjie Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Operational flexibility improvement of coal-fired power plants has become a priority objective with the high penetration of renewable energy sources. The regulating measures applied frequently in improving the operational flexibility indeed affect the exergy efficiency of coal-fired power units during transient processes. In this study, the exergy efficiency evaluation of operational flexibility measures during primary frequency control processes was focused on, and the exergy analysis methods of the thermal system were used on the basis of the second law of thermodynamics to analyze the mechanisms for improving the flexibility at four regulation measures, and the exergy storage conversion efficiency and exergy destruction accumulation were quantitatively compared. It turns out that: among the throttling extraction steam of high-pressure heaters, feedwater bypass of high-pressure heaters, and condensate water decrease of low-pressure heaters measures, the exergy storage conversion efficiency and the exergy destruction accumulation increase with the regulating time of primary frequency control. The measure of throttling extraction steam of high-pressure heaters is the most potential option for improving operational flexibility, with maximum value of the maximal output power increment and maximal exergy storage change rate of 71.11MW and -89.84 MW, respectively. With respect to the economy, the measure of throttling extraction steam of low-pressure heaters is the best option due to its smallest exergy destruction accumulation among all the measures. This study provides a detailed guidance for the selection of the optimal regulating measures when considering the enhancement of exergy efficiency and flexibility comprehensively under different conditions and periods.

关键词： Exergy analysis Operational flexibility Dynamic simulation Coal-fired power plant

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Flocculation of suspended cohesive particles in homogeneous isotropic turbulence

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JOURNAL OF FLUID MECHANICS 2021年 921卷 A17-A17页

作者： Zhao, K. Pomes, F. Vowinckel, B. Hsu, T. -J. Bai, B. Meiburg, E. UC Santa Barbara Dept Mech Engn Santa Barbara CA 93106 USA Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Tech Univ Carolo Wilhelmina Braunschweig Leichtweiss Inst Hydraul Engn & Water Resources D-38106 Braunschweig Germany Univ Delaware Ctr Appl Coastal Res Dept Civil & Environm Engn Newark DE 19716 USA

We investigate the dynamics of cohesive particles in homogeneous isotropic turbulence, based on one-way coupled simulations that include Stokes drag, lubrication, cohesive and direct contact forces. We observe a transient flocculation phase, followed by a statistically steady equilibrium phase. We analyse the temporal evolution of floc size and shape due to aggregation, breakage and deformation. Larger turbulent shear and weaker cohesive forces yield smaller elongated flocs. Flocculation proceeds most rapidly when the fluid and particle time scales are balanced and a suitably defined Stokes number is . During the transient stage, cohesive forces of intermediate strength produce flocs of the largest size, as they are strong enough to cause aggregation, but not so strong as to pull the floc into a compact shape. Small Stokes numbers and weak turbulence delay the onset of the equilibrium stage. During equilibrium, stronger cohesive forces yield flocs of larger size. The equilibrium floc size distribution exhibits a preferred size that depends on the cohesive number. We observe that flocs are generally elongated by turbulent stresses before breakage. Flocs of size close to the Kolmogorov length scale preferentially align themselves with the intermediate strain direction and the vorticity vector. Flocs of smaller size tend to align themselves with the extensional strain direction. More generally, flocs are aligned with the strongest Lagrangian stretching direction. The Kolmogorov scale is seen to limit floc growth. We propose a new flocculation model with a variable fractal dimension that predicts the temporal evolution of the floc size and shape.

关键词： suspensions sediment transport cohesive sediments

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Gasification of unsymmetrical dimethylhydrazine in supercritical water: Reaction pathway and kinetics

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2018年第18期43卷 8644-8654页

作者： Yi, Lei Guo, Liejin Jin, Hui Kou, Jiajing Zhang, Deming Wang, Runyu Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn SKLMF Xian 710049 Shaanxi Peoples R China

Unsymmetrical dimethylhydrazine (UDMH) is a high N-containing (as much as nearly 50%) substance. Traditional treatment methods such as incineration will inevitably cause the formation of nitric oxide and secondary pollution. Supercritical water is a preferred transformation medium due to its unique physicochemical properties. However, at present most of studies are limited to supercritical water oxidation (SCWO) which tends to produce hydrogen nitrate resulting in corrosion to the reactor. To conquer this problem, we propose supercritical water gasification (SCWG) technology which is in a reducing environment, realizing both harmless treatment and resource utilization. In order to promote its industrialization process, the reaction pathways and kinetic parameters should be studied. In this paper, the reaction pathways and kinetics of UDMH in supercritical water were conducted under the conditions of 400 C-degrees-550 C-degrees in quartz reactor, which avoids the catalytic effect on the reaction kinetics. From the resource utilization perspective, the most abundant quantitatively detectable gaseous product is methane, together with less hydrogen, carbon monoxide and ethane orderly. All these gaseous products are combustible. The maximum of carbon efficiency is 90.25% at 550 C-degrees, 10 min. In the point of view of harmless treatment, the organic compounds contained in the residual liquid are detected with H-1 NMR, FTIR and GC/MS. Results show that UDMH could be fully degraded within 3 min and the ultimate organic compounds in the residual liquid are mainly dimethylamino acetonitrile and trimethylamine. In addition, a reaction pathway for UDMH disposed in supercritical water is developed. Finally, the quantitative kinetic model for describing the gaseous products and ammonia-nitrogen in the residual liquid is brought forward. The pyrolysis activation energy for UDMH in supercritical water is 49.98 +/- 7.38 kJ/mol. (C) 2018 Hydrogen Energy Publications LLC. Published

关键词： UDMH SCWG Resource utilization Harmless treatment Reaction pathway Kinetics

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Analysis on the behavior of dispersed plate-type fuel based on fluid-solid coupling method

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PROGRESS IN NUCLEAR ENERGY 2020年 126卷 103398-103398页

作者： Li, Chenxi Wu, Yingwei Wang, Yangyang Wang, Kunpeng Wang, Mingjun Tian, Wenxi Su, G. H. Qiu, Suizheng Xi An Jiao Tong Univ Sch Nucl Sci & Technol Shanxi Key Lab Adv Nucl Energy & Technol State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Minist Ecol & Environm Peoples Republ China Nucl & Radiat Safety Ctr Beijing 100082 Peoples R China

In this study, a three-dimensional bi-directional fluid-solid coupling method FLUENT-ABAQUS-MpCCI was used to analyze the behavior of the fuel plate. ABAQUS was used to simulate the solid domain, including the heat conduction, mechanical behavior and irradiation effects. Several subroutines were developed and validated, including CREEP, UHARD, USDFLD and UEXPAN. FLUENT was used to simulate the fluid domain, including pressure and temperature. FLUENT and ABAQUS were coupled by MpCCI to consider the interaction between fluid domain and solid domain. Many parameters were obtained, including fluid temperature distribution, Mises stress distribution and strain distribution. The influences of the fluid domain, particle volume fraction, creep behavior and burnup were analyzed. The results showed that the zero-dimensional model or one-dimensional model on fluid could not accurately simulate the mechanical behavior of the fuel plate. The results also showed that the creep behavior could reduce the Mises stress on the cladding.

关键词： Fluid-solid coupling analysis Irradiation effects Fuel behavior analysis

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Reactivity of Ni, Cr and Zr doped ceria in CO₂ splitting for CO production via two-step thermochemical cycle

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2018年第30期43卷 13754-13763页

作者： Zhu, Liya Lu, Youjun Li, Feng Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn SKLMF Xian 710049 Shaanxi Peoples R China

This work focuses on modification and screening of ceria-based oxides for solar H2O/CO2 splitting via two-step thermochemical cycle. Ce1-xMxO2-delta (M = Zr, Ni, Cr;x = 0, 0.05, 0.10, 0.15, 0.20) were synthesized via sol-gel method and tested for CO2-splitting via two-step thermochemical cycles. Reduction was conducted at 1500 degrees C through a ramp rate of 10 degrees C/min and oxidation was performed at 1000 degrees C isothermally. Both Ni and Cr showed low solubility in ceria and no or very limited promoting effect on CO productivity. Cr could be reduced in the first reduction step but cannot be oxidized by CO2 in the following oxidation step. Zr doped sample showed advantages in both CO productivity and lattice stability. 15% Zr doped exhibited the best performance with the CO productivity of 315.40 mu mol/g. However, the oxidation rate of Zr doped samples was much lower than that of pure ceria. Compromise between fuel productivity and fast kinetics should be made in practical application. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： CO2 splitting Thermochemical cycle Solar energy Ceria-based oxides

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Characteristics of interfacial oscillation caused by condensation of steam jet in subcooled water flow

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EXPERIMENTAL THERMAL AND FLUID SCIENCE 2019年 109卷 109864-000页

作者： Xu, Qiang Chu, Xiaona Yao, Tian Liu, Weizhi Guo, Liejin Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

An experimental study is conducted to investigate interfacial characteristics of direct contact condensation of steam jet in counter-current subcooled water flow in confined conditions. A customized visualization window and a high-speed camera are combined together to capture and record the dynamical interface behavior of the condensing jet. The transient interface behavior of the jet is analyzed and discussed quantitatively by utilizing digital image processing technology. With increase of steam mass flux, the bubbling and jetting regime appear successively at subsonic conditions and sonic or supersonic conditions, respectively. The transient radial interface position along all axial locations downstream of the jet is obtained quantitatively for these two typical condensation regimes. The probability distribution function and power spectrum density of the radial interface position along all axial locations of a certain jet follow almost the same principles in the time-frequency domain. Significant variations of the probability distribution function and power spectrum density between the bubbling and jetting regimes happen at transonic condition. With increase of axial distance away from the nozzle exit, the probability of the pinch-off events first rise and then drops in subsonic and sonic conditions. While the jet interface is very stable and no pinch-off events occur in supersonic condition.

关键词： Steam condensation Interface position Jet stability Condensation regime multiphase flow

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Central-pointy to central-concave icing transition of an impact droplet by increasing surface subcooling

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INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER 2019年 108卷 104326-000页

作者： Shang, Yuheng Liu, Xiufang Bai, Bofeng Zhong, Xin Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

The effect of substrate temperature is investigated experimentally on the ice profile of an impact water droplet. A hydrophilic substrate, a relatively high impact velocity which can lead to a larger contact area, and a low surface temperature are employed aiming at enhancing the heat transfer rate through the droplet. The frozen droplet is uniquely central-concave at low surface temperatures, in contrast to the widely observed central-pointy ice formed at cold surfaces. The formation of the central-concave icing is attributed to the additional interior circular-like freezing front advancing both upwards and outwards during the solidification. Upon decreasing the surface temperature, the nucleation is triggered earlier, and the freezing rate is higher than that of a quasi-steady droplet freezing on a similar subcooled surface due to the impact-induced flattening of the droplet. A freezing regime map described by the dimensionless number representing the heat conduction rate through the substrate and Weber number consists of two regimes for the formation of the central-pointy and central-concave ice profile respectively.

关键词： Impact droplet Freezing Ice profile Spread Heat conduction rate

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Role of solid-liquid interaction energy on anomalous thermal conductivity enhancement in well-dispersed dilute nanofluids studied by equilibrium molecular dynamics

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CHEMICAL PHYSICS 2020年 539卷 110943-110943页

作者： Wang, Xin Jing, Dengwei Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Xi An Jiao Tong Univ Int Res Ctr Renewable Energy Xian 710049 Peoples R China

In this study, Green-Kubo formulism was employed to quantitatively assess thermal conductivity of nanofluids with different solid-liquid interaction energy. Anomalous thermal conductivity enhancement was observed in well-dispersed dilute nanofluids with strong solid-liquid interaction energy. The simulation results indicated that solid-liquid interaction is the key factor for the understanding of the heat conduction mechanism in nanofluids. Green-Kubo theory and Brownian motion were studied in detail to derive the physical origin of thermal conductivity enhancement. The results suggested that the phonons across the solid-liquid interface or micro-convection induced by Brownian motion of nanoparticles is responsible for thermal conductivity enhancement. In addition, a wide range of thermal conductivity enhancement and nonlinear increasing with volume fraction was observed, which is consistent with experiment investigations. The effect of solid-liquid interaction energy on the viscosity of nanofluids was also studied and was found to be an insignificant factor. Our results indicated that the nanofluids with strong solid-liquid interaction energy should have more significant application potential.

关键词： Molecular dynamics Nanofluids Thermal conductivity Viscosity Micro-convection Brownian motion

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Hybrid Photoelectrochemical Water Splitting Systems: From Interface Design to System Assembly

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ADVANCED ENERGY MATERIALS 2020年第11期10卷

作者： Niu, Fujun Wang, Degao Li, Fei Liu, Yanming Shen, Shaohua Meyer, Thomas J. Xi An Jiao Tong Univ Int Res Ctr Renewable Energy State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Univ N Carolina Dept Chem CB 3290 Chapel Hill NC 27599 USA Dalian Univ Technol State Key Lab Fine Chem Dalian 116024 Peoples R China

Photoelectrochemical (PEC) water splitting has attracted increasing attention due to its potential to mitigate energy and environmental issues. Hybrid PEC systems containing semiconductor photosensitizers and molecular catalysts are reported to be highly active and stable for water splitting with great potential for facilitating clean fuels production. In this review, following a showcasing of the fundamental details of hybrid PEC systems for water splitting, semiconductor/molecular catalyst interface designs are highlighted, with a focus on interfacial physicochemical interactions and binding, and interfacial energetics and dynamics for efficient charge transfer. Recent advances in hybrid system assemblies for PEC water splitting are also briefly introduced. Finally, future challenges and directions in the field of hybrid PEC water splitting for solar energy conversion are reviewed. The current review provides state-of-the-art strategies for optimized interface design for creating highly active and stable PEC water splitting assemblies.

关键词： artificial photosynthesis interface design photoelectrode assembly water splitting

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