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SSRN 2024年

作者： Wang, Hongbiao Xu, Jinliang Zhang, Yuqian Yan, Xin Liu, Guohua Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power University Beijing102206 China Key Laboratory of Power Station Energy Transfer Conversion and System North China Electric Power University Ministry of Education Beijing102206 China

Optical manipulation of liquids has extensive applications, ranging from biological research to information technology. However, existing technologies struggle with a fundamental limitation, as the pinning force of the contact line significantly resists liquid motion. In this study, a novel strategy is introduced to govern fluid motion and overcome this barrier. Our approach involves positioning a nanofluid slug within a sealed capillary tube and directing irradiation to one side of the slug. Intensive local vaporization is generated due to the thermo-plasmonic effect of nanoparticles, leading to a considerable driving force and rapid motion of the slug. Based on this principle, the opto-thermoplasmonic pneumatic piston was proposed. The direction of motion is controlled by modulating the irradiation direction. Furthermore, the laser beam parameters enable adjustable piston oscillation frequency and speed. To better understand the characteristics of the opto-thermoplasmonic pneumatic piston, theoretical studies were conducted to analyze the kinetic characteristics of the piston, revealing an expression consistent with the Kelvin-Voigt model. Various factors affecting the performance of the pneumatic pistons were also studied. Based on the experimental results and motion model, we found and explained that the oscillation amplitude presents an exponential relationship with the working frequency [[EQUATION]], where the coefficient a is related to the laser power, slug length, and nanofluid concentration, while the coefficient b is solely dependent on the nanofluid concentration. These opto-thermoplasmonic pneumatic pistons epitomize a new paradigm for manipulating aqueous mesoscopic systems, thus forging new paths for light-propelled soft motors with precise motion control. © 2024, The Authors. All rights reserved.

关键词： Irradiation

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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

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Nuclear Thermal Coupling Optimization of Baffled Ntp Reactor

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SSRN 2022年

作者： Duan, Zimian Zhang, Jing Han, Zichao Wang, Mingjun Wu, Yingwei He, Yanan Tian, Wenxi Qiu, Siuzheng Su, Guanghui Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Xi’an710049 China Department of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Nuclear thermal propulsion (NTP) technology has characteristics of high power and high specific impulse. In particular, CERMET fuel reactor has received a lot of research due to its simple form and structure. A general CERMET fuel reactor model is established by using three-dimensional Monte Carlo neutron dynamics program and commercial CFD program Fluent. After nuclear thermal coupling optimization, three partition schemes of baffled reactor were proposed to reduce the temperature difference between the wall and the coolant and lower the relative spike factor in the inner region. A feasible design of redundant control system was then proposed, with a cold clean excess reactivity greater than $3.44 and a minimum dry shutdown reactivity lower than -$5.95, where there was a high control accuracy of 6.7 pcm/mm. The reactor realized safety of the core temperature lower than 3000K under the conditions of total exit temperature of 2650K and thrust of 25000lb. © 2022, The Authors. All rights reserved.

关键词： Cermets

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Influence of Bi3+ Doping on the Electrochemical Properties of Ti/Sb-Sno2/Pbo2 Electrode for Zinc Electrowinning

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SSRN 2024年

作者： Wu, Jia Kang, Xuanqi Xu, Shuangwen Wei, Zhen Xu, Shangyuan Liu, Kang Feng, Qing Jia, Bo Wang, Yunhai Xían Taijin New Energy & Materials Sci-Tech CO. Ltd Xi’an710016 China Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiao tong University Xi’an710049 China

Bi3+ doped Ti/Sb-SnO2/PbO2 electrode materials were fabricated by electrodeposition to improve its electrochemical performance in zinc electrowinning. The surface morphology, chemical composition and hydrophilicity of the as-prepared electrodes are characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and contact angle. The electrochemical measurement and the accelerate lifetime experiment are also conduct to investigate the electrocatalytic performance and stability of the electrodes. The results showed that Bi3+ modification electrode has an important effect on the coating morphology, crystal structure, surface hydrophilicity, electrocatalytic activity and stability. The electrode prepared from the solution containing 2 mmol·L-1 Bi(NO3)3 (marked as the Ti/Sb-SnO2/2Bi-PbO2 electrode) exhibits the best hydrophilicity performance (θ=21.6°) and the longest service life (1196 h). During the electrochemical characterization analysis, the Ti/Sb-SnO2/2Bi-PbO2 electrode showed the highest oxygen evolution activity, which can be attributed to the highest electroactive surface (qT*=21.20 C·cm-2) and the best charge transfer efficiency. DFT calculation demonstrate that the doping of Bi lead to the decrease in the OER reaction barrier and increase the DOS of the electrode, which further enhanced the catalytic activity and conductivity of the electrode. Moreover, the simulated zinc electrowinning experiment demonstrate that the Ti/Sb-SnO2/2Bi-PbO2 electrode consume less energy than other electrodes. Therefore, it is expected that the Bi modified electrodes may become a very promising electrode material for zinc electrowinning in the future. © 2024, The Authors. All rights reserved.

关键词： Hydrophilicity

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Correlation Analysis for Online CO 2 Leakage Monitoring in Geological Sequestration

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Energy Procedia 2013年 37卷 4374-4382页

作者： Denglong Ma Jianqiang Deng 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

The paper presents a method for monitoring CO 2 leakage in geological carbon dioxide sequestration. The unsteady state dispersion of leakage CO 2 from geosequestration simulation results showed that the ensemble trend of elevated concentration caused by CO 2 leakage can be viewed as a concentration step change perturbation to the background variation and the initial stage of dispersion process is an increasing variation. The correlation between O 2 and CO 2 variation is well linear if there is no leakage. The external linear perturbation decreases the correlation coefficient. Moreover, too large step change concentration will also reduce the average correlation coefficient. Therefore, online correlation analysis between O 2 and CO 2 in atmosphere is useful to distinguish the leakage CO 2 from complex background variation especially at the beginning of leakage occurring.

关键词： Geosequestration Carbon storage CO 2 leakage monitoring Correaltion analysis

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Thermal Stress in a Circular Nano-Inhomogeneity

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SSRN 2022年

作者： Huang, Haojie Xing, Shichao Song, Kun School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China School of Energy and Power Engineering Shanghai Key Laboratory of Power Enegy in Multiphase Flow and Heat Transfer Shanghai China Key Laboratory of Construction Hydraulic Robots of Anhui Higher Education Institutes Tongling University Tongling244061 China School of Mechanical and Power Engineering Nanjing Tech University 30 Puzhu South Road Jiangsu Nanjing China

The thermal stress of nanocomposites is worth studying in that the extreme stress affects its reliability. In this paper, we propose a set of interfacial conditions to simulate the interfacial phonon scattering and interfacial elasticity in the nanocomposite, and obtain closed-form solutions for the thermal-elastic fields around the circular nano-inhomogeneity. The results show that the interfacial thermal stress within matrix is more sensitive to interfacial phonon scattering than that in the nano-inhomogeneity, while the size change of inhomogeneity has greater impact on the stress of the nano-inhomogeneity than that of the matrix. In view of the significant effects of thermal conductivities and thermal expansion coefficients on the thermal stress around inhomogeneity, the maximum von Mises stress is reduced up to three orders of magnitude by adjusting these parameters. More importantly, the thermal stresses within matrix and inhomogeneity can be respectively designed as "zero" even though the nanocomposite is subjected to a large thermal loading, which is viewed as an update mechanism of "neutral inhomogeneity". Our work provides guidance for the design of nanocomposites and has important potential applications. © 2022, The Authors. All rights reserved.

关键词： Thermal stress

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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

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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 1400 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

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Experimental Studies of Liquid Immersion Cooling for 18650 Lithium-Ion Battery Under Different Discharging Conditions

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SSRN 2022年

作者： Li, Yang Zhou, Zhifu Hu, Leiming Bai, Minli Gao, Linsong Li, Yulong Liu, Xuanyu 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 Department of Mechanical Engineering Carnegie Mellon University Pittsburgh15213 United States

In this study, the fluorinated liquid immersion cooling as a new cooling scheme has been tested and discussed for cooling the 18650 lithium-ion battery. OpteonTM SF33, with boiling point of 33.4oC, is chosen as the fluid for the immersion cooling. Comparison of the liquid immersion cooling and convective air cooling for a 18650 lithium-ion battery under 2C, 4C and dynamic load conditions are made. It is found that the immersion cooling better cools the battery cell under all these conditions. Under 4C discharging, the maximum cell temperature rise is 14.06°C for the forced air cooling, while is 4.97°C for the liquid immersion cooling. As the cooling fluid’s temperature basically governs the battery cell temperature, the cooling fluid’s temperature should not be too low. This study demonstrates that the lithium-ion battery has non-negligible power losses under cooling liquid temperature of 10oC and 15oC, compared with temperature above 20oC. Lastly, the two-phase boiling heat transfer mechanisms associated with immersion cooling of lithium-ion battery are discussed with bubble dynamics analysis. It is found under higher C rate, more aggressive boiling heat transfer is induced. The battery temperature is controlled to be below 34.5oC even under 7C discharging condition. © 2022, The Authors. All rights reserved.

关键词： Lithium-ion batteries

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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

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