检索结果-内蒙古大学图书馆

Optimization of anode performance in the ethanol electrochemical reforming for clean hydrogen production

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2021年第1期46卷 119-133页

作者： Ying, Zhi Geng, Zhen Zheng, Xiaoyuan Dou, Binlin Cui, Guomin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

Carbon-based fuel electrochemical reforming is considered as a promising hydrogen production method. Ethanol is one of the most appropriate carbon-based fuels. In this work, anode performance, especially the flow, ethanol electro-oxidization and energy consumption in the ethanol electrochemical reforming is numerically studied and experimental verified. Take the straight serpentine channel with square cross-section as a base structure in the electrochemical cell (EC), the effects of channel geometry and operating parameters are analyzed. Another five different configurations of flow channels, as well as another three different cross-sections are designed and explored. Results indicate that at the same cross-section area, the wider channel provides the higher effective area for proton transfer, and thereby improves the electrode reactions. The appropriate decrease of inlet velocity or increase of input voltage promotes the anode reaction and reduces the pressure drop in channel, while the operating temperature has the opposite effects on ethanol conversion and pressure drop. The arc channel is found optimal considering its highest ethanol conversion, although its pressure drop is a bit higher. The sector crosssection with uniform flow field distribution is found most favorable for the straight serpentine channel considering the ethanol electro-oxidization. These findings will favor the improvement of EC. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Electrochemical reforming Ethanol Electrochemical cell flow channel Hydrogen

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Thermogravimetric kinetics on catalytic combustion of bituminous coal

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JOURNAL OF THE ENERGY INSTITUTE 2020年第6期93卷 2526-2535页

作者： Zhang, Hao Dou, Binlin Li, Jingjing Zhao, Longfei Wu, Kai Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

The catalytic combustion and non-isothermal kinetics of bituminous coal by CeO2, Fe2O3, and NiO were investigated. The exothermic characteristics during catalytic combustion of bituminous coal were determined. Based on the Coats-Redfern method by introducing the function of kinetics mechanisms, the activation energies and pre-exponential factors of catalytic combustion of bituminous coal were estimated iteratively by regression. It is found that the catalysts promoted the transport of oxygen to the coal or char surface and effectively improved the combustion characteristics of bituminous coal. Under the same experimental conditions, the exothermic values were significantly increased and the catalysts of composite oxides exhibited higher exothermic values than pure metal oxide catalysts. The metal oxides significantly reduced the activation energies of bituminous coal combustion. SEM analysis presented that combustion residues became more porous with the addition of the catalyst. (C) 2020 Energy Institute. Published by Elsevier Ltd. All rights reserved.

关键词： Bituminous coal TGA-DSC Catalytic combustion Thermogravimetric kinetics

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An experimental investigation of sessile droplets evaporation on hydrophilic and hydrophobic heating surface with constant heat flux

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INTERNATIONAL COMMUNICATIONS IN heat AND MASS transfer 2017年 88卷 262-268页

作者： Gao, Ming Kong, Peng Zhang, Li-Xin Liu, Jing-Nan Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

Droplet evaporation widely exists in the daily life and industrial production. In most of previous experimental studies, the evaporation of sessile droplets was conducted under a constant substrate temperature condition. However, drops often evaporating on a heating surface under a constant heat flux condition in many practical applications. In this paper, we have carried out an experiment on sessile 3 mu l DI water droplets evaporated on hydrophilic and hydrophobic heating surfaces under constant heat flux in the range from 1153 W/m(2) to 6919 W/m(2). A high-speed camera was used to record the changing shapes of two sessile droplets on a hydrophilic and a hydrophobic heating surface placed side by side. The droplet height, dynamic contact angle, droplet contact diameter, evaporation mode and evaporation rate are presented.

关键词： Droplet evaporation Contact angle Wettability Constant heat flux

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Ensemble learning with member optimization for fault diagnosis of a building energy system

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ENERGY AND BUILDINGS 2020年 226卷 110351-110351页

作者： Han, Hua Zhang, Zhan Cui, Xiaoyu Meng, Qinghong Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

For better service and energy savings, improved fault detection and diagnosis (FDD) of building energy systems is of great importance. To achieve this aim, ensemble learning is investigated and introduced in this study. Three types of methods like K-nearest neighbor (KNN), support vector machine (SVM), and random forest (RF) are carefully selected, optimized, and integrated into an ensemble diagnostic model (EDM) by the majority voting method. Experimental data for seven typical gradual faults in a centrifugal building chiller are used for model validation and evaluation. The results show that the diagnostic accuracy of the EDM (99.88%) is higher than that of the individual methods, with significant improvements for normal operation and refrigerant leakage, and no false alarms reported. Models based on ensemble learning, EDM and RF (homogenous ensemble), exhibit better performance for global faults, which are difficult to diagnose. In addition, five different feature sets are selected from the literature for further tests. It is found that the diagnostic performance depends not only on the principle of diagnosis, but also on the fault category and the characteristics of the feature set such as the indicative degree to corresponding faults, number of features, correlation degree between features, and information redundancy, and feature selection is proved to be more important than algorithm selection in fault diagnosis practice. Ensemble learning is proved to be a promising candidate for the fault diagnosis of building energy systems, except for the Zhou-8 feature set (eight temperature features), for which KNN is a better choice. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Refrigeration system Fault diagnosis Ensemble learning Majority voting Features

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A laser interference/high-speed photography method for the study of triple phase contact-line movements and lateral rewetting flow during single bubble growth on a small hydrophilic heated surface

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INTERNATIONAL COMMUNICATIONS IN heat AND MASS transfer 2019年 100卷 111-117页

作者： Liu, Jing-nan Gao, Ming Zhang, Ling-shuang Zhang, Li-xin Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Sch Energy & Power Engn Shanghai 200093 Peoples R China

The laser interferometric method and high-speed camera techniques are used simultaneously to study dynamic characteristics of a single vapor bubble growth and departure from an ITO heater surface submerged in ethanol. Two high-speed cameras are used simultaneously in this experiment: one is used to record interference fringes of the microlayer at the bubble's bottom and the other is used to record the growth and detachment of the single bubble synchronously from the side view. By comparing these images frame by frame, it is found that the bubble's growth time can be divided into two periods sequentially: the microlayer period and the lateral rewetting period. Variations of dry spot radius, bubble contact radius, bubble volume and diameter, dynamic contact angles during these two periods are illustrated.

关键词： Bubble growth Microlayer Rewetting Interferometric method

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Novel application of multi-model ensemble learning for fault diagnosis in refrigeration systems

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APPLIED THERMAL engineering 2020年 164卷 114516-000页

作者： Zhang, Zhan Han, Hua Cui, Xiaoyu Fan, Yuqiang Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

Despite the importance of fault diagnosis in refrigeration systems, the performance and improvement of most existing diagnostic models are limited by their reliance on a single method. This study proposes a novel application of ensemble learning that incorporates several intelligent ensemble members into an integrated model by means of majority voting. The ensemble members include k-nearest neighbour (KNN), support vector machine (SVM), decision tree (DT), random forest (RF) and logistic regression (LR). ASHRAE fault data were employed to establish the model. In addition, this study explores the integration of different subsets of ensemble members and revealed that the optimum subset combination comprised KNN, DT, and RF. Although the accuracy of this model was slightly lower than the model with all five ensemble members, it realised a substantial reduction in runtime. Compared to an SVM optimization model, the integrated model realised higher accuracy and reduced training time, without requiring parameter optimization. This achievement merits note as ensemble learning is traditionally associated high time-costs. Further investigation revealed that both the diversity and high accuracy of ensemble members are required to obtain an effective integrated model. These observations demonstrate the proposed model offers a promising alternative solution for fault diagnosis in refrigeration systems.

关键词： Refrigeration system Fault diagnosis Integrated model Majority voting Parameter optimization

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Characterization of soot based on variable laser-induced spectroscopy

Characterization of soot based on variable laser-induced spe...

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Digital Holography and Three-Dimensional Imaging, DH 2016

作者： Chen, Jun Zhang, Yanfeng Yan, Huinan Su, Mingxu School of Energy and Power Engineering Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering China

The soot raise great environmental and health problems. Conventional methods don ' t have such low measurement limits. So in this paper soot's component and size information will be studied in theory and exper... 详细信息

ISBN: (纸本)9781943580156

关键词： Soot

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Experimental investigation of Marangoni convection in a sessile droplet at a constant heat flux condition

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INTERNATIONAL COMMUNICATIONS IN heat AND MASS transfer 2020年 115卷 104600-104600页

作者： Gao, Ming Zhang, Da Kong, Peng Zhang, Li-xin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

Droplet evaporation is a common physical phenomenon, widely used in the life, science, industry and other fields. During evaporation of the droplets, the surface tension changes due to the non-uniformity of vapor-liquid interface temperature, and the Marangoni convection is generated. Previous studies mainly focused on constant wall temperature condition, but less on constant heat fluxes condition. In this paper, a 5 mu l R113 sessile droplet evaporated on a hydrophilic heating surface with a constant heat flux ranging from 0 similar to 3575W/m(2) was studied. A high-speed camera and an infrared camera were used to record the dynamic characteristics of the droplet evaporation phenomenon in the horizontal and vertical directions respectively. The Marangoni phenomenon of losing stability, evaporation time, the dynamic contact angle, the number of ripples, cell body diameter were present in this paper.

关键词： Droplet evaporation Constant heat flux Marangoni convection Hydrothermal wave

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Evaporation dynamics of different sizes sessile droplets on hydrophilic and hydrophobic heating surface under constant wall heat fluxes conditions

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INTERNATIONAL COMMUNICATIONS IN heat AND MASS transfer 2018年 93卷 93-99页

作者： Gao, Ming Kong, Peng Zhang, Li-xin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

In this study, an experimental investigation has been carried out to study evaporation of sessile droplets with different volumes on a heating surface under constant heat flux conditions. In this experiment, two sessile droplets were placed on a hydrophilic and a hydrophobic heating surface side by side. The droplets size ranged from 2 mu l to 5 mu l, and heat flux ranged from 1272 W/m(2) to 7810 W/m(2). A high-speed camera was used to record the changing shapes of two sessile droplets. Effects of droplet size on dimensionless contact angle, dimensionless contact diameter, dimensionless droplet height and dimensionless evaporation rate, are presented.

关键词： Droplet evaporation Contact angle Wettability Constant heat flux Drop size

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Improvement and experimental study of scroll expander for organic rankine cycle

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Energy engineering: Journal of the Association of Energy engineering 2020年第4期117卷 225-235页

作者： Li, Lei Tao, Leren Gou, Yanan Zhang, Shan Zaozhuang University Zaozhuang277160 China University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China

The scroll expander used in organic Rankine cycle (ORC) system is improved, and its performance is analyzed experimentally. The modified profile and inlet hole of the scroll expander are enhanced, and the performance of the scroll expander before and after the improvement is analyzed. The results show that when the inlet pressure exceeds 0.7 MPa, the waist-shaped hole with a larger area is preferable. The scroll expander with a waist-shaped hole has a larger output power and wider optimal pressure range, and when the inlet pressure is 1.6 MPa, the maximum output power increases by 230 W. The output power and isentropic efficiency of the scroll expander can be improved by modifying the profile. When the inlet pressure is 1.6 MPa and the rotational speed is 1750 r/min, the maximum output power of the scroll expander is 1235 W, which is 120 W higher than that before the improvement. © 2020, Tech Science Press. All rights reserved.

关键词： Rankine cycle

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