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SSRN 2023年

作者： Ren, Jiyun Li, Yuhang Jin, Xiaoling Huang, Xiaole Li, Yang Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Xi’an Thermal Power Research Institue Co. Ltd. Xi’an710032 China

Oxygen-steam gasification of biomass is a promising technology because of its ability to improve syngas quality and reduce energy consumption. In this study, a fixed-bed reactor is employed to assess the effects of inherent alkali and alkaline earth metals (AAEMs) on the catalytic gasification of candlenut wood with large particle size under oxygen-stream atmosphere. The results show that the acid-washing would remarkably remove the inherent AAEMs in biomass, which is affected by the grain direction. In terms of the gasified chars derived from acid-washed biomass, AAEMs content gradually decreases along the end surface and radial direction, which could also be observed from the 3D reconstruction of X-ray CT images. In all biomass samples and gasified chars, micropores (0-1. μm) dominate and are distributed along the grain direction. In general, pores of 20-30 μm and above 30 μm comprise a minor proportion. Inherent AAEMs facilitate an augmentation in char yield as well as BET and total pore volume of gasified char. AAEMs and grain direction have a slight effect on functional groups of gasified chars. The tar component is remarkably affected by the grain direction. Acid-washing pretreatment augments the content and organic species of M2-M4 compounds (containing 2-4 benzene rings) in the tar. It also leads to a decrement in concentrations of H2, CH4, and CO2 by 1..49% and 1..35%, 0.51. and 0.89%, 2.32% and 1.37% in syngas for two-grain direction, respectively. But it raises the CO concentration by 1..1. and 1..1.%, resulting in a reduction of 4.09% and 1.53% in syngas calorific value. A decrement in the volume fraction of CnHx induced from AAEMs is significantly affected by the grain direction. © 2023, The Authors. All rights reserved.

关键词： Biomass

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Investigation of the Solar-Driven Chemical Looping Methane Dry Reforming on Rh-Doped LaCeO3.5 Oxygen Carrier

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SSRN 2024年

作者： Li, Peng Gai, Zhongrui Zhang, Jinrui Rao, Qiong Tang, Sanli Shen, Yuanhui Pan, Ying Jin, Hongguang Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China University of Chinese Academy of Sciences Beijing100049 China

The feasibility of a solar-driven chemical looping dry reforming of methane (DRM) process, which converts solar energy and methane into syngas via a looping material oxygen carrier is investigated experimentally. Thermogravimetric analysis (TGA) experiments were firstly carried out to verify the effect of the Rh-doped LaCeO3.5 which were synthesized via modified Pechini method and incipient wetness method and the result shows that Rh greatly improved the reaction kinetics. Photo-TGA experiments were conducted to evaluate the light effect in chemical looping DRM. Under the light condition, the Rh-doped LaCeO3.5 shows higher methane conversion, oxygen extraction rate and CO selectivity compared with the undoped one, decreasing the apparent activation energy of the reaction at the same time. Insights obtained from the UV-Vis spectroscopy verified that the surface Rh under the light could promote the activation of surface methane species and increase the light absorbance. Meanwhile, the FEM methods were used to obtain the distributions of the temperature fields of the photo-TGA reactor through the calculation of the coupling of the fluid, reaction and temperature fields. In this way, the conversion mechanism of the solar, heating and chemical energy was illustrated and furthermore, the calculated surface reaction rate and the variation tendency of the outlet-gas were consistent with the experimental results. Through the integration of solar energy, a high methane to solar fuel conversion efficiency could be achieved. The proposed process has the potential to produce solar fuels at high efficiency with reduced carbon footprint. © 2024, The Authors. All rights reserved.

关键词： Methane

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Proposal and thermodynamic analysis of a steam methane reforming system integrated with thermochemical energy storage and a SCO2 brayton cycle

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Journal of Energy Storage 2025年 127卷

作者： Fu, Yu Liu, Ming Wang, Zhu Xie, Tao Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Institute of Industrial Catalysis School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 China

Solar energy is a promising alternative to fossil fuels for providing heat in steam methane reforming (SMR) hydrogen production. However, the variability of solar energy requires effective storage solutions. This study presents a new SMR hydrogen production system that integrates thermochemical energy storage (TCES) utilizing a CaO/CaCO3 cycle with a SCO2 Brayton cycle. The system converts fluctuating solar energy into the stable chemical energy of CaO by calcinating CaCO3 in the solar calciner, with the SMR reaction mainly heated by the exothermic reaction of CaO and CO2. The SCO₂ Brayton cycle efficiently recovers heat from the high-temperature SMR products. Comprehensive thermodynamic analysis and evaluation models are developed. Results show that the proposed system performs well, achieving energy and exergy efficiencies of 73.49 % and 78.46 %, respectively, under benchmark conditions. The energy storage efficiency of TCES is 81.55 %, and the solar-to-chemical energy efficiency is 48.21.%. Integrating TCES significantly enhances the system's steady operation under fluctuating solar energy conditions. The calciner accounts for the largest share of exergy destruction at 31.63 %, followed by the carbonator at 1..50 %. Sensitive analyses of key operating parameters indicate that higher CaO conversion rate and storage temperature enhance energy storage, energy, and exergy efficiencies. Besides, the energy and exergy efficiencies decrease with the increasing SMR reaction pressure but increase with rising reaction temperature. When the S/C is 2.0, these efficiencies reach their maximum values of 75.42 % and 78.63 %, respectively. © 2025 Elsevier Ltd

关键词： Brayton cycle

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Best estimate plus uncertainty analysis of the China advanced large-scale PWR during LBLOCA scenarios

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International Journal of Advanced Nuclear Reactor Design and Technology 2020年 2卷 34-42页

作者： Chang, Yuhao Wang, Mingjun Zhang, Jing Tian, Wenxi Qiu, Suizheng Su, G.H. Department of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

China advanced large-scale Pressurized Water Reactor (PWR) implements series of passive safety systems to provide core cooling and decay heat removal in case of some unexpected accidents. The development of reactor best estimate system analysis codes has realized the transition from conservative safety analysis to Best Estimate plus Uncertainty (BEPU) analysis for the purpose of achieving more realistic results and digging larger safety margins. The BEPU analysis during Large Break Loss of Coolant Accident (LBLOCA) has been widely used for the licensing application of Nuclear power Plants (NPPs). In this paper, the BEPU analysis of China advanced large-scale PWR was performed under the conditions of LBLOCA scenarios employing RELAP5 code. The models of reactor coolant system with all the passive safety systems were established and the influence of uncertainties of important parameters on the Peak Cladding Temperature (PCT) was evaluated. The results show the obtained PTC (1.1. K) through the BEPU analysis is far below the 1.CFR50.46 PCT acceptance criteria (1.77 K) in case of LBLOCA and is also lower than the conservative calculation value (1.48 K), indicating a larger safety margin. This work provides a meaningful evaluation method for China advanced large-scale PWR safety assessment. © 2020 Xi'an Jiaotong University

关键词： Pressurized water reactors

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Investigation of Thermal Radiative Transfer Characteristics of Single Water Droplet

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SSRN 2023年

作者： Zhang, Dan Tu, Maoping Yuan, Yang Han, Wei State Key Laboratory of Multiphase Flow in Power Engineering School of Energy & Power Engineering Xi'an Jiaotong University Shaanxi Xi’an710049 China Xi'an Thermal Power Research Institute Co. Ltd Shaanxi Xi’an710054 China

Directly heat water droplet by thermal radiation was the key process of coupling solar energy to achieve green production in many industrial applications, such as desalination, carbon capture, energy storage, and so on. The radiative transfer of single water droplet for given irradiation, including reflection, absorption, transmission and their dependences on external irradiation, droplet geometry and radiative properties were investigated through a calculation model set up according to zone method. In current study, the ranges of equivalent diameter and length-width ratio of droplet were 0.1.1.0 mm, 1.1. respectively, its absorption coefficient was 1.-1.000 m-1.and refractive index was 1.2-2.0. Results suggested that, (1. the absorption mode of droplet could be classified into surface absorption (SA) and volumetric absorption (VA) depending on whether its optical thickness was greater than 1. In VA, droplet could get uniform and fast temperature increasing, and its absorptivity and mean temperature increase rate could be simultaneously improved by increasing absorption coefficient. (2) Scattering included reflection and transmission. Compared with incident irradiation, reflection distributed mainly on the same side of droplet's long axis, while transmission mainly on the opposite side. The overall reflectivity increased with rising refractive index, but was independent on droplet size. While its transmissivity increased with enlarging length-width ratio or reducing equivalent diameter. (3) In VA, at least 40% of incident irradiation was scattered out. The total quantity of scattering could be adjusted by changing absorption coefficient in VA or refractive index in SA. The proportion of transmission in scattering could always be increased by reducing refractive index. © 2023, The Authors. All rights reserved.

关键词： Drops

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Comprehensive Parameter Analyses on Steam-Air Condensation at Equal- Height-Difference Natural Circulation Loop Under Large Air Mass Fraction

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SSRN 2024年

作者： Chen, Weixiong Wang, Han Li, Sinian Kai, Hui Zhao, Quanbin Li, Shaodan Wang, Jinshi State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Missile Engineering College Rocket Force University of Engineering 710025 China Science and Technology on Thermal Energy and Power Laboratory Wuhan 2nd Ship Design and Research Institute Wuhan430205 China

With the development of small-sized reactors, a passive containment cooling system (PCCS) named equal-height difference natural circulation loop (EHDNCS) has been developed. Experiments were conducted at higher air mass fractions to evaluate the condensation heat transfer coefficient (HTC) as a function of steam-air mixture pressure, air mass fraction, and wall subcooling. The results indicate that the condensation HTC decreases with increasing air mass fraction and increases with increasing steam-air mixture pressure in the containment. The relationship between condensation HTC and air mass fraction gradually transitions from non-linear to linear as the steam-air mixture pressure increases. The condensation HTC increases with increasing wall subcooling;However, for air mass fractions greater than 75%, the condensation HTC remains nearly constant with changes in wall subcooling. A quantitative relationship between the condensation HTC and the height of the PCCS (sum of riser height and 0.5 times heat exchanger height) has been derived by calculating the cooling water flow driving force and resistance in the natural circulation loop. The applicable conditions for optimizing the riser height and the initial ratio of the riser to heat exchanger height to enhance the heat transfer {1. of the PCCS were proposed. Based on the experimental results, an empirical correlation equation for predicting the condensation HTC for PCCS with EHDNCS is established, with a prediction deviation within ±31.. © 2024, The Authors. All rights reserved.

关键词： Heat exchangers

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Unveiling micro- and nanoscale bubble dynamics for enhanced electrochemical water splitting

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Advances in Colloid and Interface Science 2025年 343卷 103544页

作者： Lu, Xinlong Yadav, Devendra He, Baichuan Zhou, Yu Zhou, Liwu Zeng, Zilong Ma, Lijing Jing, Dengwei International Research Center for Renewable Energy & State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China Department of Chemical Engineering Technion - Israel Institute of Technology Haifa3200003 Israel College of Mechanical Engineering Xi'an Shiyou University Shaanxi Xi'an710065 China

Bubbles generated during electrochemical and photoelectrochemical water splitting critically influence efficiency through complex factors, including chemical reactions, species transport, mass transfer at the three-phase interface, and bubble coverage. A detailed understanding of the nucleation, growth, coalescence, and detachment of micro- and nanoscale bubbles is vital for advancing water splitting technologies. Surface-attached bubbles significantly reduce the electrocatalytically active area of electrodes, leading to increased surface overpotential at a given current density. Consequently, their effective removal is pivotal for optimizing the electrolysis process. However, the intricate interplay among single bubble evolution, mass transport, bubble coverage, and overpotential remain inadequately understood. This review explores the fundamental mechanisms underpinning bubble evolution, with an emphasis on the Marangoni effect and its influence on bubble dynamics. Furthermore, recent advancements in understanding individual bubbles on micro and nano-electrodes are highlighted, offering valuable insights into scale-dependent bubble behavior. These findings enrich our knowledge of gas-liquid interfacial phenomena and underscore their industrial significance, presenting opportunities to enhance water splitting performance through optimized bubble dynamics. © 2025

关键词： Electrolysis

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Preliminary Conceptual Design with Neutronics and Thermal-Hydraulics Assessments of Fustar

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SSRN 2023年

作者： Zhou, Xingguang Zhang, Dalin Li, Xinyu Lv, Xindi Jiang, Dianqiang Tian, Wenxi Qiu, Suizheng State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi'an Jiaotong University Xi'An710049 China

The fluoride-salt-cooled high-temperature advanced reactor (FuSTAR) is an advanced small modular reactor, which aims to the electric supplement and clean heat production to western China. In this study, neutronics and thermal-hydraulics analysis are also carried out, and established the core layout and material ratio under the near-critical condition. The parameters of the designed core are evaluated quantitatively from various aspects. The results show that FuSTAR has sufficient shutdown depth, the equilibrium cycle is 3.24 years, and the discharge burnup depth is 1.6 GWd/MtU. The analysis of 1.6 core porous media shows that the peak fuel temperature under normal operating condition is 1.09.3 K, which is far below the limit of 1.73 K. Relevant design and analysis results can provide the reference for the subsequent small modular FHR design and construction. © 2023, The Authors. All rights reserved.

关键词： Computational fluid dynamics

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Thermodynamic Analysis and Optimization of Two-Step Supercritical Water Desorption-Gasification System of Oily Sludge

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SSRN 2024年

作者： Zhang, Chenghao Wang, Gaoyun Zhao, Qiuyang Gao, Yunbo Ge, Zhiwei Jin, Hui Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No. 28 Xianning West Road Xi’an710049 China Technical Inspection Center Sinopec Shengli Oilfield Company Dongying257000 China

The two-step supercritical water desorption-gasification (TSSCWDG) technology can significantly improve the gasification efficiency of oil sludge. However, few works have been conducted to explore the influence of operating parameters on this process. In this paper, a novel desorption-gasification process modeling was constructed based on the supercritical water gasification (SCWG) of oily sludge and the influences of different operating parameters on the system efficiencies were investigated. Increasing the separation temperature and the desorption levels can achieve the rapid improvement of the efficiencies of the TSSCWDG system, but more desorption levels may increase the complexity of the system and the operating cost. The desorption temperature had a relatively small impact on the system efficiencies, but the lower desorption temperature was beneficial to the utilization of industrial waste heat and decreasing the operating cost. Moreover, the TSSCWDG system was optimized and analyzed, and the optimized system had achieved the energy matching between the gasification products and unites, resulting in significant reduction of the irreversible losses in each unit, which the energy efficiency of the optimized system reached 83.4%. This work could provide essential theoretical guidance for the scale-up and design of the industrial application of SCWG of oil sludge with hydrogen production. © 2024, The Authors. All rights reserved.

关键词： Desorption

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Thermodynamic Analysis on Supercritical Water Gasification of Oily Sludge Using a Continuous Two-Step Method

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SSRN 2024年

作者： Wang, Gaoyun Zhang, Chenghao Zhao, Qiuyang Gao, Yunbo Jin, Hui Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No. 28 Xianning West Road Xi’an710049 China Technical Inspection Center Sinopec Shengli Oilfield Company Dongying257000 China

A large amount of oily sludge is produced every year around the world and the traditional treatment techniques for oily sludge have deficiencies of incomplete processing and high energy consumption. Supercritical water gasification (SCWG) technology can cleanly convert oily sludge into hydrogen-rich gas and does not require an energy-consuming drying process. This work constructed the desorption-gasification two-step SCWG system based on the previous experimental study and investigated the influences of feed concentration, gasification temperature and sludge compositions on the energy efficiency and exergy efficiency of the system. The results showed that the two-step system had higher energy efficiency and exergy efficiency, as well as better adaptability to various sludge compositions under maintaining high efficiency conditions. The energy efficiency and exergy efficiency of the two-step system were 61.2% and 45.3% respectively under the gasification temperature of 600 ℃ and the feed concentration of 1.0wt%, which were 91.95% and 93.67% higher than those of the single-step system. Additionally, the desorption unit of two-step system operated at lower temperature, resulting in decreased use of high-temperature resistant materials and reduced economic costs. This research provides valuable insights into the construction and optimization of two-step SCWG of oily sludge. © 2024, The Authors. All rights reserved.

关键词： Desorption

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