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Catalytic Gasification of Large Particle Size Biomass with Loaded Aaems Under Oxygen-Steam Atmosphere

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SSRN 2023年

作者： Ren, Jiyun Yang, Kaixuan Li, Yuhang Bai, Yang Jiang, Jiahao Huang, Xiaole 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 Shanghai Power Equipment Research Institute Co. Ltd. Shanghai200240 China Xi’an Thermal Power Research Institue Co. Ltd. Xi’an710032 China

To evaluate the effect of alkali and alkaline earth metals species (AAEMs) on the catalytic gasification of large particle size biomass, a vertical fixed-bed reactor is conducted for candlenut wood gasification under the oxygen-stream atmosphere. The gasification chars derived from gasification are characterized by SEM, X-ray CT, BET, and FTIR. Tar and syngas are analyzed via GC-MS and GC respectively. Advanced X-ray CT technology provides beneficial visualization to assist in the interpretation of the catalytic gasification of large particle size biomass loaded with AAEMs. The results indicate a progressive augmentation of AAEMs content along the radial direction and end surface for all loaded samples and gasification chars, which could also be visualized from the 3D reconstruction of X-ray CT. Many large pores (40-60 μm) aligned along the grain direction collapse after gasified and generate numerous micropores in gasification chars. 1.-20 μm pores are more prominent in chars loaded with KCl and CaCl2. The char loaded with CaCl2 has more well-developed pores, a larger specific surface area, and -OH compounds, aldehydes, ketones and carboxylic acids. The addition of AAEMs facilitates the high generation of M1.compounds (contains 1.benzene ring) in the tar and suppresses the enhancement of other compounds, M4 compounds, and long-chain alkanes. H2 and CO concentrations augments and declines by loading AAEMs. The highest H2 concentration of 62.1. is detected by the addition of CaCl2. When loaded with KCl, the syngas calorific value reduces by 1.37%, while loaded with NaCl, CaCl2, and MgCl2 show an augmentation of 1..48%, 1..56%, and 2.55%, respectively. A decrement of CnHx concentration in syngas derived from samples loaded with KCl and MgCl2 and an increment one loaded with NaCl and CaCl2 are acquired. © 2023, The Authors. All rights reserved.

关键词： Oxygen

Overall Mass Transfer Coefficient of CO 2 Absorption in a Diameter-varying Spray Tower

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Energy Procedia 2017年 114卷 1665-1670页

作者： Xiaomei Wu Min He Yunsong Yu Zhen Qin Zaoxiao Zhang School of Chemical Engineering and Technology Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China

The application of spray towers for CO 2 capture is a development trend in recent years. However, most of the previous jobs were conducted in a cylindrical tower by using a single spray nozzle, whose configuration and performance is not good enough for industrial application. To solve this problem, the present work proposed a diameter-varying spray tower and a new spray mode of dual-nozzle opposed impinging spray to enhance the absorption performance of CO 2 spray absorption process. Experiments were conducted to investigate the effects of varies operating parameters on the overall mass transfer coefficient in various operating conditions. Experimental results showed that liquid to gas ratio and mole ratio of MEA to CO 2 are key factors which affect the performance of CO 2 absorption process and the maximum overall mass transfer coefficient for the diameter-varying dual-nozzle opposed impinging spray tower is 0.4773 kmol·m -3 ·h -1.·kPa -1..

关键词： CO 2 capture diameter-varying spray tower overall mass transfer coefficient absorption performance

Efficient Water Recovery and power Generation System Based on Air-Cooled Fuel Cell with Semi-Closed Cathode Circulation Mode

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SSRN 2024年

作者： Yang, Yuchen Wu, Zhen Yao, Jing Wang, Bofei Yang, Fusheng Zhang, Zaoxiao Ren, Jianwei School of Chemical Engineering and Technology Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Mechanical Engineering Science University of Johannesburg Johannesburg2092 South Africa

Air-cooled proton exchange membrane hydrogen fuel cell with on-line hydrogen production by hydrolysis has potential for portable applications due to its high volumetric power density and self-humidification. However, plenty of reserve water significantly reduces the power density of fuel cell system. Moreover, water recovery from fuel cell tail gas is difficult, because the tail gas humidity is very low due to excess cathode air as coolant. In this work, the dead-ended anode and semi-closed cathode proton exchange membrane fuel cell is proposed to achieve efficient water recovery and energy conversion via semi-closed cathode circulation mode. In this mode, cathode O2-poor tail gas is recycled as coolant instead of fresh air, which helps to enlarge the tail gas humidity by reducing the stoichiometric ratio of cathode to anode gas. The system lumped model with detailed component description is developed for optimization. More than 96% water production can be recycled under atmosphere temperature. The demand of fresh air is greatly reduced from 56 to 2 times of the consumption. Besides, the multi-objective optimization between water recovery and electrochemical performance shows high-efficiency water recovery of 94.70% and high energy conversion efficiency of 54.82%. © 2024, The Authors. All rights reserved.

关键词： Cathodes

Rate-limiting factors in thin-film evaporative heat transfer processes

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arXiv

arXiv 2024年

作者： Zhao, H. Poole, R. Zhou, Z. Wolfson School of Mechanical Electrical and Manufacturing Engineering Loughborough University Loughborough LeicestershireLE11 3TU United Kingdom State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

In this paper, we present a theoretical study aimed at investigating the rate-limiting factors in thin-film evaporative heat transfer processes, considering the finite-rate evaporation kinetics. The problems of evaporation of a flat thin-film in either pure vapours or vapour-inert-gas mixtures are analysed based on the non-dimensionalised macroscopic transport equations for continuum fluids, coupled with out-of-equilibrium kinetic boundary conditions. Both the full numerical solutions and asymptotic analytical solutions at slow evaporation limit are provided and applied to analyse thin water film evaporation. Existing solutions, assuming negligible heat transfer in the gas domain, or negligible temperature jump across the non-equilibrium kinetic layer, or more boldly a thermodynamically equilibrial interface (i.e. its temperature is at the saturation temperature), can be fully recovered from the more general solutions presented here. Our results show that while these assumptions hold in special cases, they can lead to significant errors in many conditions, especially when the film thickness δ is reduced to a few micrometers or thinner. We show that the conventional views that the rate-limiting factors in thin-film evaporative heat transfer is either the heat diffusion through the liquid film or the mass transfer in the gas domain only apply to thick film (i.e. δ λ where λ is the mean free path in the vapour phase). As δ decreases to a few micrometer or smaller (more precisely when the Knudsen number Kn increases beyond O(1. in an pure vapour environment or when the kinetic Peclet number Pe is reduced below O(1. in inert gases), the interfacial thermal resistance due to the evaporation kinetics can be on the same orders of magnitude as the thermal resistance in the liquid film. The analysis also allow us to compare the heat transfer processes during the evaporation of a thin-film in pure vapours to those in inert gases, providing deeper insight into the effectiveness

关键词： Thin films

Computational Study of CO 2 Absorption in Aqueous and Non-aqueous Solutions Using MEA

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Energy Procedia 2014年 63卷 1347-1353页

作者： Tingting Zhang Zaoxiao Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China School of Chemical Engineering and Technology Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China

Chemical absorption using Ethanolamine to capture CO 2 is considered to be an effective way to cover the large reduction of the greenhouse gas emissions. As the absorption capacity is different between aqueous and non- aqueous solutions, in this work, the reaction processes about monoethanolamine (MEA) absorbing CO 2 in aqueous and non-aqueous (take methanol as the medium) solvation effect without solvent molecular are studied using density functional theory (DFT), respectively. The result shows that the reaction mechanism is same both in aqueous and non-aqueous solutions and a two-step reaction process can demonstrate it well. The main effect of the different solvent on the reaction is the relative energy of the optimized configurations. The energy shows that stable configurations have lower relative energy in methanol than in water, which demonstrates that the configurations are more stable in non-aqueous solutions than those in aqueous solutions.

关键词： CO 2 absorption DFT MEA water methanol solvation effect

Development and Assessment of a Novel Air/Water Hybrid Cooling System Coupling Two Units for Energy and Water Saving

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SSRN 2022年

作者： Wang, Jinshi Xue, Kai Zhang, Guilong Chen, Weixiong Li, Gen Zhang, Juntai Zhang, Guozhu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China School of Electric Power Engineering South China University of Technology Guangzhou510641 China Datang Environment Industry Group Co. Ltd. Beijing100097 China

For the purpose of reducing coal consumption, decreasing CO2 emission, and improving economic interests of thermal power plants, a novel air/water hybrid cooling system coupling two units has been developed and assessed. The hybridization is achieved by the heat exchange of the circulating cooling water from two units, which is appropriate for the power plants with both water-cooling units and indirect air-cooling units, such as in North China region. Two schemes with different circulating water returning positions were compared on basis of thermodynamic and economic evaluation. Finally, the scheme that cooled circulating water was introduced to the air-cooling tower outlet was considered as the optimal design, which has the coal saving rate of 1.43 g/kWh at the design condition, with a 3.59-year payback period. In addition, this work focused on operation strategies to obtain optimum operation range, contributing to less coal consumption in summer and less water consumption in winter. The results indicate that annual coal consumption can be reduced by about 1.00 tons in the reference power plant, the CO2 emission is decreased by 3490 tons, and 50000 tons of water could be saved. This technology is expected to be further promoted to practical engineering for the sustainable development. © 2022, The Authors. All rights reserved.

关键词： Thermoelectric power plants

Clogging failure in microfilter for blood cell separation and its novel improvements

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Clogging failure in microfilter for blood cell separation an...

International Symposium on Physical & Failure Analysis of Integrated Circuits

作者： Tao Dong Zhaochu Yang Eirik Bentzen Egeland Frank Karlsen Henrik Jakobsen Norwegian Center of Expertise on Micro-and Nanotechnology I.M.S.T. /R. I Vestfold University College Norway State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

Clogging failure is common for microfilter utilizing the flat membrane structure. To reduce clogging failure in microfilters, the turbine blade-like micropillar is introduced in microfilter design. Two improved cross-flow microfilter designs employing the blade-like micropillar barrier are presented, one with varied cross-section channels, and the other with Archimedes' spiral channels. Analogy experimental-data based simulations show that the two aforementioned novel microfilters have good filtrating efficiency and fantastic anti-clogging characteristics. And the commercial value of the turbine blade-like barriers is affirmed by the industry Partners.

关键词： Microfiltration Cells (biology) Filters Biomembranes Filtration Turbines White blood cells Nanotechnology Educational institutions power {1.

Inverse Analysis of Radiative Properties of Internal Medium and Surface for Cylindrical System Using Csm-Cgm Approach

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SSRN 2023年

作者： Zhang, Chao Li, Ben-Wen Zhou, Rui-Rui Li, Pan-Xin Huang, Ling-Yun Key Laboratory of Ocean Energy Utilization and Energy Conservation Ministry of Education School of Energy and Power Engineering Dalian University of Technology Dalian116024 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization Faculty of Land Resource Engineering Kunming University of Science and Technology Kunming650093 China

An inverse analysis is conducted to simultaneously estimate the radiative properties in a 2D cylindrical system including the extinction coefficient, scattering albedo, and the wall emissivity from the knowledge of the radiative heat flux over different boundaries. In which the collocation spectral method (CSM) is developed to solve the forward problem, the conjugate gradient method (CGM) is employed to solve the inverse problem, and the complex-variable-differentiation method is used to treat the sensitivity problem, separately. Meanwhile, the effects of measurement errors, initial values, and imaginary values of complex variables on the precision of the inverse analysis are investigated. Results show that the proposed inverse analysis can successfully retrieve the unknown radiative physical properties of 2D cylindrical system. Under the same physical properties, good inversion results can be obtained by using different wall (end walls and side wall) radiative heat fluxes, but the inversion efficiency from sidewall radiative heat flux is higher. Besides, it is found that, the inversion for the scattered participating medium is more efficient than that for the non-scattered participating medium;the true values and iterative convergence values have little effect on the inversion result;the influence of the initial values and the imaginary values of the complex variable on the inversion cannot be ignored. © 2023, The Authors. All rights reserved.

关键词： Conjugate gradient method

Numerical Simulation for Non-Uniform Ptco Catalyst Degradation Under Constant Voltage Condition and its Impact on Pemfc Performance

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SSRN 2023年

作者： Yang, Yunjie Bai, Minli Zhou, Zhifu Wu, Wei-Tao Hu, Chengzhi Gao, Linsong Li, Yang Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116023 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

PtCo alloys are commonly utilized as catalysts in proton exchange membrane fuel cell (PEMFC) to reduce Pt loading and to achieve higher oxygen reduction reaction (ORR) activity. However, long-time operation can result in a reduction in electrochemical surface area (ECSA) in PEMFC. Meanwhile, the dissolved Co2+ may also contribute to additional local oxygen transport resistance. In this study, catalyst aging model and Co2+ transport and its effect on oxygen transport model have been integrated with the 3D single phase PEMFC performance model to develop a long-term performance model for investigating the impact of non-uniform catalyst degradation and Co2+ contamination on PEMFC performance during constant voltage operation. The results show that Co2+ contamination causes additional mass transfer losses and reduces the peak power of PEMFC. And it is found that the non-uniform degradation of catalyst and Co2+ contamination eventually affects the current density distribution in aged PEMFCs. In addition, the model is also applied to study a 50 cm2 PEMFC under long time constant voltage operation. The predicted ECSA loss is 73.1. and 62.0%, and output power reduction is 55.9% and 43.0% after 80,000 hours at a constant voltage of 0.75 V and 0.65 V, respectively. © 2023, The Authors. All rights reserved.

关键词： Numerical models