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Vapor-liquid equilibrium of H2/CO2 and H2/N2/CO2 mixture, the liquefaction technology related to the supercritical water gasification products

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Vapor-liquid equilibrium of H2/CO2 and H2/N2/CO2 mixture, th...

International Multidisciplinary Conference on Computer and Energy Science (SpliTech)

作者： Hongtu Wu Hui Jin School of Energy and Power Engineering Xi’an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi’an China

In this paper, the dew point and liquid phase composition of H 2 /CO 2 and H 2 /CO 2 /N 2 mixtures at phase equilibrium calculated by PR-BM equation and Van Der Waal mixing rule with commercial MATLAB software are introduced, it is of theoretical significance for the wide application of the products of supercritical water gasification. First, the results obtained by the self-programming code are verified with the experimental data, the experimental data and simulation results of two kinds of CO 2 /H 2 mixtures and two kinds of CO 2 /N 2 /H 2 mixtures were compared. The average percentage deviation was 2.69%, 4.05%, 2.22%, 1.20%, respectively. Thus the absolute deviations of the mixtures are within the acceptable range, therefore, the model proposed in this paper can well predict the dew point of the mixtures composed of H 2 /CO 2 or H 2 /CO 2 /N 2 .Afterwards, the dew point and the CO 2 content in the liquid phase of common H 2 /CO 2 and H 2 /CO 2 /N 2 vapor mixtures in supercritical water gasification products were predicted, and a series of analysis and discussion were conducted on the predicted results finally.

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Analysis for fuel rod performance under LOCA based on the FROBA-ROD 2.0 code

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International Journal of Advanced Nuclear Reactor Design and Technology 2021年 3卷 54-65页

作者： Liao, Haoyu Li, Chenxi He, Yanan Wu, Yingwei Zhang, Yapei Tian, Wenxi Su, G.H. Qiu, Suizheng School of Nuclear Science and Technology Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Loss of Coolant Accident (LOCA) is one of the major design-basis accidents in LWRs. Fuel rod may fail due to the rupture of the cladding. By developing a LOCA simulation module, the steady-state fuel rod performance analysis code, FROBA-ROD, is now capable to predict fuel rod behaviors under a LOCA transient. The relevant models and the code was verified and validated by comparing with authoritative commercial codes and with the experimental measurements. Comprehensive calculations and analyses of fuel rod behaviors under different LOCA transients were performed by the new version of FROBA-ROD. Compared the failure conditions to the non-failure conditions through the simulation results, a cladding failure threshold equation was found for a better estimate of the integrity of high burnup fuel rods under LOCA transients. © 2021 Xi'an Jiaotong University

关键词： Loss of coolant accidents

Genetically engineered nifA mutations in Rhodobacter capsulatus to enhance ammonium tolerance and hydrogen production

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International Journal of Hydrogen Energy 2025年 144卷 252-261页

作者： Zixuan Gao Xintong Gao Yu Ma Zhixuan Jiao Minmin Wang Xuefang Mu Jiali Feng Wen Cao Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China College of Biology and Oceanography Weifang University Weifang 261061 Shandong China

NifA, the activator of nitrogenase, is sensitive to ammonium concentration, particularly within its N-terminal domain. In this work, genetically engineered mutants with N-terminal deletions of the nifA1 and nifA2 genes were constructed using overlap extension PCR to reduce the inhibitory effect of ammonium on nitrogenase expression in Rhodobacter capsulatus SB1003. Under 3 mM NH 4 + , the hydrogen production rate of ZX03 ( nifA1 - , nifA2 - ) reached 0.65 mmol L −1 h −1 , with a 31.2 % increase in hydrogen production compared to the wild-type. When 8 mM NH 4 + was used as the sole nitrogen source, H 2 production in all strains decreased substantially compared to 5 mM NH 4 + . However, ZX03 demonstrated a 5.2-fold enhancement in hydrogen production relative to the wild-type under 8 mM NH 4 + , underscoring its improved ammonium tolerance. During hydrogen production, the gene expression levels of nifA and nifH in all mutant strains were significantly up-regulated under ammonium conditions compared to the wild-type. These findings reveal distinct roles of nifA1 and nifA2 in ammonium tolerance and hydrogen production.

关键词： Gene splicing N-terminal Nitrogenase expression Photo fermentative hydrogen production Transcriptional activator

Simultaneous Analysis of Liquid Film Instabilities and Properties of Swirl Sprays by Telecentric Shadowgraphy

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SSRN 2023年

作者： Machado, Danilo Almeida Costa, Fernando S. Dias, Gabriel Silva Mota, Fábio A.S. Combustion and Propulsion Laboratory National Space Research Institute SP Cachoeira Paulista12630-000 Brazil State Key Laboratory of Multiphase Flows in Power Engineering Xi’an Jiaotong University Shanxi Xi’an710049 China

A telecentric shadowgraphy optical system was utilized to determine macroscopic and microscopic parameters of sprays and the measurement of conical liquid films formed by dual pressure swirl injectors. Spray cone angles, breakup lengths, mean droplet velocities, momentum flows, wave amplitude ratios and maximum wave growth rates were simultaneously measured using high-speed images with kHz frequencies. Two injectors were tested with inner nozzles having Abramovich geometric constants Kint = 2 and 2.125 and external nozzles with geometric constants Kext = 2.9 and 1.9792, respectively. Injection pressures were varied from 0.05 to 0.5 MPa and water was used as test fluid. The experimental data indicate that the breakup length, droplet velocity, flow momentum and disturbance amplitude ratio are higher for injectors with larger mass flow rates, for a given injection pressure. On the other hand, the maximum wave growth rate of the liquid film is higher for injectors with smaller mass flow rates. The maximum amplitude ratios of the conical liquid film disturbances varied in the range 2.32 © 2023, The Authors. All rights reserved.

关键词： Liquid films

Effect of Fuel System on the Heat Releasing Method and Flow-Path Design of Rocket-Based Combined Cycle Engine 14

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Effect of Fuel System on the Heat Releasing Method and Flow-...

14th International Conference on Mechanical and Aerospace engineering, ICMAE 2023

作者： Liu, Xiao Wang, Yinhu Yang, Yiyan Shi, Lei Yan, Dekun Xi'An Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an China Beijing Institute of Long March Vehicle Beijing China Northwestern Polytechnical University Science and Technology on Combustion Internal Flow and Thermal-structure Laboratory Xi'an China

ISBN: (纸本)9798350340327

Multi-components rocket-based combined cycle (RBCC) engine is widely applied in most two-stage-To-orbit program due to stable operation performance under variable flight conditions. Present researches numerically compared RBCC's performance under ramjet mode and scramjet mode, respectively, by using two fuel system, hydrogen and kerosene together with a \mathrm{k}-\omega SST turbulence model. Researches showed that the combustor area ratio should be increased to keep stable pressure difference balance between inflow and flame because of higher caloric value using hydrogen. Distributed heat addition method is benifit for overall performance improvement when using hydrogen. Different from using kerosene, head should be delayedly added in combustor downtream under scramjet mode. Moreover, the advanced heat addition amount should be decreased under ramjet mode to ensure effective isolator operation. © 2023 IEEE.

关键词： Hydrogen

state-of-the-art progress in overall water splitting of carbon nitride based photocatalysts

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Frontiers in Energy 2021年第3期15卷 600-620页

作者： Bing LUO Yuxin ZHAO Dengwei JING School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049China International Research Center for Renewable Energy and State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Converting solar energy into hydrogen(H_(2))by photocatalytic water splitting is a promising approach to simultaneously address the increasing energy demand and environmental *** decade has passed since the discovery of photo-induced water splitting phenomenon on TiO_(2)photoanode,while the solar to H_(2) efficiency is still around 1%,far below the least industrial ***,developing efficient photocatalyst with a high energy conversion efficiency is still one of the main tasks to be *** carbon nitride(g-C_(3)N_(4))is just such an emerging and potential ***,in this review,the state-of-the-art advances in g-C_(3)N_(4)based photocatalysts for overall water splitting were summarized in three sections according to the strategies used,and future challenges and new directions were discussed.

关键词： photocatalysis overall water splitting carbon nitride hydrogen

Modeling of Transition from Stratified Flow to Condensation-Induced Water Hammer in Horizontal Steam-Water Pipes

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SSRN 2023年

作者： Liu, Wenbing Wang, Zichen Zhao, Quanbin Chong, Daotong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Kelvin-Helmholtz (K-H) instability theory is extensively used to predict the transition from stratified flow to slug flow. This study developed a one-dimensional (1-D) model based on K-H theory and considering the variation of axial wave amplitude to predict the transition from stratified flow to condensation-induced water hammer (CIWH). The prediction results of the present model were compared with the experimental data and the results of Taitel’s model. The comparison shows that the present model could reasonably predict critical instability, which is the boundary between stratified flow and CIWH. Critical instability is divided into three types according to the wave amplitude of critical instability. Critical instability occurs at the upper limit, middle, and starting point of the exponential growth of wave amplitude under low, medium, and high liquid levels. The effects of major parameters, including liquid level, water temperature, pipe diameter, and pipe length, on the critical inlet steam velocity and position of critical instability were analyzed. When the liquid level increases, the critical inlet steam velocity decreases, then increases, and then decreases, and the position of critical instability moves downstream, then upstream, and finally turns to the steam inlet. The effect of water temperature, pipe diameter, and pipe length on the critical instability depends on the liquid level and is complex. © 2023, The Authors. All rights reserved.

关键词： Condensation

Exergy-Based Control Strategy Design and Dynamic Performance Enhancement for Parabolic Trough Solar Receiver-Reactor of Methanol Decomposition Reaction

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SSRN 2023年

作者： Zhang, Peiye Liu, Ming Mu, Ruiqi Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

The parabolic trough solar receiver-reactors of methanol decomposition reaction (PTSRR-MDR) enable efficient hydrogen production with solar energy at users' end. Solar fluctuations affect the solar-to-chemical efficiency, hydrogen yield and system stability, indicating the necessity for an appropriate control strategy. In this study, dynamic and thermodynamic models of PTSRR-MDR with Cu/ZnO/Al2O3 as catalyst were developed. Results of thermodynamic analysis show that an optimal flow rate exists for methanol to achieve the maximum solar-to-chemical exergy efficiency of the PTSRR-MDR. The temperature increases sharply and exceeds the catalyst sintering temperature when the methanol flow rate decreases under its optimal value. Then, control objectives to achieve the maximum efficiency were obtained with a temperature of 3 °C to guarantee the PTSRR-MDR safety. Control strategies based on Dynamic Matrix Control (DMC), Forward-Feedback Control (FFC) and Ramp Control (RC) were evaluated under cloud shading/recovering and real radiation processes. Results show that strategies based on DMC, FFC, and RC increase the solar-to-chemical exergy efficiency from 14.76% to 16.31%, 16.28% and 15.65%, respectively. The Integral Squared Error (ISE) for methanol conversion rate under three methods are 1.46, 0.32 and 5.28, respectively, indicating that strategy based on FFC is considered most suitable for PTSRR-MDR operation control. © 2023, The Authors. All rights reserved.

关键词： Methanol

Enhancement of Scr Denitrification Control Strategy Considering Fluegas Temperature Fluctuation: Fundamental Principle and Performance Evaluation

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SSRN 2023年

作者： Gao, Wei Yin, Junjie Liu, Ming Zhao, Yongliang Wang, Chaoyang Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Nitrogen oxides (NOx) is one of the main pollutants in coal-fired power plants, and selective catalytic reduction (SCR) is widely applied to reduce NOx emissions. Coal-fired power plants should frequently change their output power to help the power grid to accommodate high penetration of intermittent renewable power. However, NOx emission transient overshoot often occurs in coal-fired power plants when coal-fired power plants dynamically change their output power. In this study, the dynamic models for a coal-fired power plant and SCR denitrification are developed. The fluegas temperature fluctuation is revealed as a key cause for the NOx emission transient overshoot. The change law of SCR reaction temperature during load cycling processes is obtained, and its prediction model based on neural network algorithm is developed. Then, an enhanced control strategy considering temperature fluctuation of SCR inlet fluegas is proposed, and denitrification performance with the original and enhanced control strategies during load cycling processes are compared. The results show that the transient overshoot of NOx outlet concentration is avoided during load cycling processes, and the maximum value of NOx emissions during loading down and loading up processes with the enhanced control strategy are 48.62 and 49.44 mg m−3, which decreases by 7.36 and 4.63 mg m−3 compared with the original control strategy, respectively. Moreover, when the enhanced control strategy is adopted, the cumulative NH3 consumption decreases by 0.48 and 11.84 g m−3 during loading down and loading up processes, respectively. © 2023, The Authors. All rights reserved.

关键词： Coal fired power plant