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Dynamic Analysis and Optimization of Heat Transfer Performance During Electrospray Cooling with Ethanol-R141b Mixture

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SSRN 2022年

作者： Tian, Jiameng Kong, Lingwen Li, Bufa Wang, Junfeng Chen, Bin Xiong, Junhui School of Energy and Power Engineering Jiangsu University Zhenjiang212013 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Zhejiang Ningbo315201 China

Electrospray (ES) cooling that relies on Coulomb forces for energy-efficient liquid atomization is promising to meet the requirement of high-heat-flux thermal dissipation for micro-sized electronics under relative low... 详细信息

关键词： Ethanol

Thermodynamic analysis on a heat-power decoupling system integrated with absorption heat pump

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Thermodynamic analysis on a heat-power decoupling system int...

2019 Canadian Society for Civil engineering Annual Conference, CSCE 2019

作者： Wang, Liyuan Liu, Ming Fu, Yue Liu, Jiping Yan, Junjie MOE Key Laboratory of Thermal Fluid Science Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an Shaanxi China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an Shaanxi China

ISBN: (纸本)9780791883747

Because of the continuous expanding of the district heating, the heating load of combined heat and power(CHP) plants increases year by year. The minimum power load of CHP plant increases with the heating load due to the heat-power coupling mechanism. Therefore, heat-power decoupling is necessary to improve the operation flexibility for CHP units. Integrating the absorption heat pump(AHP) is an effective method to realize the heat-power decoupling. In this study, a 330MW CHP unit model and AHP model have been developed and validated. The performance of the heat-power decoupling and energy saving performance has been investigated by comparing the thermodynamic performance indicators. Results show that, the proposed system can increase the maximum heating load and decrease the power generation when the primary network return temperature is decreased. When the heating steam extraction is kept constant, with the increase of the primary network return water temperature, the heat generation efficiency and the standard coal consumption rate of heating increases, the coal consumption rate of power generation and the heating efficiency decreases. And the primary network return water temperature increases from 40 °C to 70 °C, the coal consumption rate of power generation decreases by 4.3 g/kWh, and the coal consumption rate of heating increases by 0.67 kg/GJ. Copyright © 2020 ASME.

关键词： Water temperature

Research on a Poly-Generation System for Gas-Biochar-Heat-Electricity by Supercritical Water Gasification of Biomass Waste

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SSRN 2024年

作者： Wang, Cui Jin, Hui School of Water and Environment Chang'an University Xi’an710054 China Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of the Ministry of Education Chang'an University Xi’an710054 China Key Laboratory of Eco-hydrology and Water Security in Arid and Semi-arid Regions of Ministry of Water Resources Chang’an University Xi’an710054 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China Ministry of Education of China Chongqing University Chongqing400044 China

Biomass energy is renewable and rich in the world, providing a solution for the shortage in fossil fuel and serious environmental pollution. Proposing efficient utilization method of biomass waste demands urgent attention. Supercritical water gasification (SCWG) process is a potential technology. In this work, a poly-generation system based on SCWG was developed to convert biomass waste to gas, biochar, heat and electricity. Firstly, mass, energy, and exergy flow were calculated at the typical condition. Subsequently, impact of various operating parameters on the hydrogen-rich syngas yield, generated electricity, thermodynamic performance was investigated. The result demonstrated that the exergy loss primarily occurred on cooler, reactor, heat exchanger and preheater, accounting for more than 90% of total exergy loss, arising from irreversible reaction, heat transfer and heat dissipation. Higher temperature, biomass concentration and preheated water exerted a positive effect for hydrogen-rich gas production and supplied heat energy, while these parameters were disadvantageous to exergy efficiency. Biochar energy was affected by biomass concentration. Energy efficiency increased with preheated water quantity and biomass concentration rising, and impact of biomass concentration was more significant. Conversely, evaluated gasification temperature displayed an adverse effect on energy efficiency. The maximal exergy efficiency reached 58.3% at 550℃, 33%, 900 kg·h-1. © 2024, The Authors. All rights reserved.

关键词： Biomass

pH-Triggered Hydroxylated Surface with Rapid Hydroxyl Radical Generation Boosts Efficient Noble-Metal-Free Pilot-Scale Photoreforming of Lignocellulose for Hydrogen Production

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SSRN 2023年

作者： Liu, Feng Fu, Yiwei Lu, Kejian Wang, Shujian Wang, Biao Huang, Jie Yan, Xueli Zheng, Yiqun Guo, Liejin Liu, Maochang International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi’an710049 China School of Chemistry Chemical Engineering and Materials Jining University Shandong Qufu273155 China Suzhou Academy of Xi’an Jiaotong University Jiangsu Suzhou215123 China

Photocatalytic H2 prodcution from lignocellulosic biomass photoreforming is deemed to be a promising alternative to overall water splitting owing to its more sustainable and value-added oxidation half-reaction. However, an efficient lignocellulose photoreforming system toward H2 production, especially at the pilot scale, is scarce and exigent to date. Herein, we present a lignocellulose photoreforming system containing noble-metal-free particulate twinned Cd0.5Zn0.5S nanocatalyst, water, and lignocellulose, enabling an unprecedented H2 evolution activity with an apparent quantum yield of 12.74% at 400 nm. Subsequently, an outdoor 7.2-m2 compound parabolic concentrator-based reactor is developed to scale up this system to a practical level with a H/2 production rate of 615 mL h-1 under direct solar irradiation. We demonstrate that a pH-triggered hydroxylated surface over Cd0.5Zn0.5S nanotwins enables superior hole transfer and rapid hydroxyl radical generation by inducing favorable reaction kinetics/thermodynamics in alkaline solution. Our work thus provides a state-of-art example of pilot-scale system for the practical Hsub>2 production via lignocellulose photoreforming. © 2023, The Authors. All rights reserved.

关键词： Lignocellulose

Experimental study of bubble behaviour in a flowing liquid layer

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Experimental study of bubble behaviour in a flowing liquid l...

2020 International Conference on Nuclear engineering, ICONE 2020, collocated with the ASME 2020 power Conference

作者： Zhang, Zhengzheng Li, Liangxing Zhang, Shuanglei Saleem, Afnan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xianning West Road 28# Xi'an city710049 China

ISBN: (纸本)9780791883785

A visualized experimental system is designed and constructed to investigate the bubble dynamic in a flowing liquid layer. Motivated by reducing uncertainties and digging a deep understand on the formation mechanism of boiling bubbles, the bubbles are formed by injecting air through a submerged orifice in our present work, where the influence of thermal physics, nucleation site density and dry spot are stripped. The water flow rate and the air flow rate are in the range of 72-324 ml/min and 0.8-2.0 ml/min, respectively. The bubble formation process in the smooth channel and the rib channel are investigated. The results state that increasing the liquid flow rates lead to the increasing bubble detachment frequency and the decreasing bubble detachment volume. Besides, the larger the liquid flow rate is, the closer the bubble center of mass is to the wall. The rib has a significant influence on the bubble formation process. In the rib channel, it is more difficult for bubbles to detach from the orifice compared that in a smooth channel. Besides, the bubble detachment volume in a rib channel is larger than it in a smooth channel. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Liquid films

Research on a Poly-Generation System for Gas-Biochar-Heat-Electricity by Supercritical Water Gasification of Biomass Waste

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SSRN 2024年

Biomass energy is renewable and rich in the world, providing a solution for the shortage in fossil fuel and serious environmental pollution. Proposing efficient utilization method of biomass waste demands urgent attention. Supercritical water gasification (SCWG) process is a potential technology. In this work, a poly-generation system based on SCWG was developed to convert biomass waste to gas, biochar, heat and electricity. Firstly, mass, energy, and exergy flow were calculated at the typical condition. Subsequently, impact of various operating parameters, including gasification temperature, mass flowrate of preheated water, biomass concentration, on the hydrogen-rich syngas yield, generated electricity, thermodynamic performance of the system was investigated. The result demonstrated that the exergy loss primarily occurred on cooler, reactor, heat exchanger and preheater, accounting for more than 90% of total exergy loss under different conditions, arising from irreversible reaction, heat transfer and heat dissipation. Higher temperature, higher biomass concentration and more preheated water exerted a positive effect for hydrogen-rich gas production and supplied heat energy, while these parameters were disadvantageous to exergy efficiency. Biochar energy was primarily affected by biomass concentration. Energy efficiency increased with preheated water quantity and biomass concentration rising, and impact of biomass concentration was more significant. Conversely, evaluated gasification temperature displayed an adverse effect on energy efficiency. The maximal exergy efficiency reached about 58.3% at 550°C, biomass concentration of 33%, preheated water mass flowrate of 900 kg·h-1 © 2024, The Authors. All rights reserved.

关键词： Biomass

A Thermal Calculation Model for Tubular Condensing Heat Exchanger

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SSRN 2023年

作者： Han, Lei Yang, Kaixuan Yang, Jiahui Li, Ruiyu Li, Yuhang 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 Shunde Institute of Inspection Guangdong Institute of Special Equipment Inspection and Research Foshan528300 China Xi’an Thermal Power Research Institute Co. Ltd. Xi’an710032 China

The condensing heat exchanger is commonly applied in various heat exchange systems. It can efficiently recover moisture and heat from the flue gas that contains water vapor. However, the convective-condensation heat transfer process is so complicated that no mature thermal calculation model is available. This study develops a thermal calculation model for the widely employed tubular condensing heat exchanger in industry. To characterize the degree of the heat and mass transfer, this study introduces two parameters, namely the sensible and latent heat transfer efficiencies of fin. The thermal calculations are conducted for the condensing heat exchangers reported in the literature to verify the proposed model by comparing it with the experimental data. The results show that the absolute error of the calculated sensible and latent heat transfer efficiencies is 0.0365 and 0.0268, respectively. A maximum difference of 5.2 K has been acquired between the measured and calculated values of the outlet temperature. The relative error of the condensate water flowrate is mostly within ±5.0% and ±10.0% under the bare-tube and finned-tube conditions, respectively, with a maximum deviation of 0.7 and 1.4 kg h-1. This study provides a general model for designing and optimizing various tubular condensing heat exchangers accurately. © 2023, The Authors. All rights reserved.

关键词： Mass transfer

Microwave-assisted synthesis of bimetallic NiCo-MOF-74 with enhanced open metal site for efficient CO 2 capture

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Environmental Functional Materials

Environmental Functional Materials 2022年第3期1卷 253-266页

作者： Changwei Chen Mohammadreza Kosari Meizan Jing Chi He State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi PR China Department of Chemical and Biomolecular Engineering Faculty of Engineering National University of Singapore 10 Kent Ridge Crescent 119260 Singapore Department of Chemistry Key Laboratory of Organic Optoelectronics & Molecular Engineering of Ministry of Education Tsinghua University Beijing PR China National Engineering Laboratory for VOCs Pollution Control Material & Technology University of Chinese Academy of Sciences Beijing 101408 PR China

Metal–organic frameworks (MOFs) containing two different inorganic metal nodes (known as bimetallic MOFs) could exhibit enhanced CO 2 adsorption compared to their monometallic counterparts. Herein, a series of bimetallic NiCo-MOF-74 synthesized by microwave-assisted method were investigated for CO 2 adsorption. It was revealed that narrow micropore channel with open metal site (OMS) of the bimetallic NiCo-MOF-74 influence CO 2 binding affinity and CO 2 /N 2 adsorption. The CO 2 uptake of Ni 1 Co 1 -MOF-74 at 0 °C and 1 bar (100 kPa) was 8.30 mmol g −1 which is higher than those of Ni-MOF-74 (3.99 mmol g −1 ), Ni 6 Co 1 -MOF-74 (3.62 mmol g −1 ), Ni 1 Co 6 -MOF-74 (6.40 mmol g −1 ) and Co-MOF-74 (5.03 mmol g −1 ). While this could be related to the high specific surface area of Ni 1 Co 1 -MOF-74, Ni 1 CO 2 -MOF-74 with relatively low specific surface areas still shows good CO 2 adsorption capacity up to 5.70 mmol/g, which is higher than those of adsorbents Ni-MOF-74, Ni 6 Co 1 -MOF-74 and Co-MOF-74, indicating that adsorption performance mainly relies on coordinated metals. Ni 1 Co 1 -MOF-74 showed remarkable recyclability performance, ranking selectivity of CO 2 /N 2 reach up to 34, and suitable isosteric heat (31–23 kJ mol −1 ), manifesting a great probability for industrial CO 2 capture. As revealed, incorporated Ni 2+ /Co 2+ nodes within Ni 1 Co 1 -MOF-74, which are acting as active and open sites for CO 2 capture, led to the synergetic effects comprising of micropores as well as dense dual-metal sites.

关键词： Bimetallic metal–organic frameworks NiCo-MOF-74 Microwave-assisted synthesis Open metal site CO 2 capture

The Role of Particle-Vortex Interaction in Hydraulic Performance and Erosion Behavior of Semi-Open Centrifugal Pump: Effect of Particle Size

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SSRN 2023年

作者： Wang, Kai Liu, Hanyu Wang, Like Guo, Pengcheng Wang, Yueshe Yang, Junfeng State Key Laboratory of Eco-hydraulics in Northwest Arid Region Xi’an University of Technology No.5 Jinhua South Road Xi’an710048 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an710049 China Shaanxi Provincial Dongzhuang Water Conservancy Engineering Co. Ltd Xi’an713200 China

The interaction between the particle migration and vortex evolution aggravates the complexity of erosion on the flow components. In this work, the liquid-solid two-phase flow of semi-open centrifugal pump under different particle sizes is simulated based on the four-way coupling Euler-Lagrange method, in which the fluid-particle interaction and particle-particle interaction are taken into account. The interrelationship among vortex structure, particle migration and surface erosion behavior is revealed. The results show that the erosion area is mainly distributed in the blade leading edge, the pressure surface inlet edge and the hub. When the particle size is 0.1 mm and 0.3 mm, due to the good following characteristic of particles and the inhibition effect on tip leakage vortex, the particles are easy to impact the outlet edge of blade suction surface and the hub, which induce severe erosion. As the particle size decreases, the number of particles flowing into the tip clearance layer increases. Therefore, the frequent impact of particles on the tip leakage vortex leads to the breakup, separation and refusion of the vortex, which aggravates the flow instability. This paper provides a new insight into the hydraulic performance and erosion characteristics of semi-open centrifugal pump in terms of particle-vortex interaction. © 2023, The Authors. All rights reserved.

关键词： Particle size