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Thermochemical conversion of sewage sludge-derived hydrochars: Volatiles release and char gasification kinetics

JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS 2021年 156卷 105138-105138页

作者： Zheng, Xiaoyuan Huang, Jin Ying, Zhi Ji, Shasha Feng, Yuheng Wang, Bo Do, Binlin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Heat Transfer & Multiphase Flow Shanghai 200093 Peoples R China Shanghai Urban Construct Design & Res Inst Shanghai 200125 Peoples R China Tongji Univ Thermal & Environm Engn Inst Sch Mech Engn Shanghai 200092 Peoples R China

Hydrothermal carbonization (HTC) combined with subsequent thermochemical conversion is an effective approach for sewage sludge (SS) to energy. In this work, HTC pretreatment of SS was performed. Then the properties of released volatiles and the remaining char-CO2 gasification after pyrolysis were evaluated via the multiple kinetic model and combined instrumental analyses. The gasification behavior of these samples exhibited slightly different due to high ash content and limited fixed carbon, although the aromatic structure in the hydrochars developed as HTC proceeded. Kinetic analysis indicated that volume reaction model (VRM) with chemical reaction order of 1.5 showed high correlation coefficients (R-2 >0.99) for all carbonized samples. There was an obvious kinetic compensation effect in the char gasification step, and activation energy (E) and pre-exponential factor (A) of these samples followed a positive correlation relationship as lnA = 0.1037 x E + 0.3579. The formation of fixed carbon in the hydrochar samples was conserved during pyrolysis, which lowered the average gasification reactivity of char. Py-GC/MS demonstrated that the chemical composition of pyrolytic volatiles was found to be mainly determinant by HTC conditions. The share of aromatics in the volatiles was in a positive correlation with the evolution of carbon functionality in the hydrochar samples. Above in all, HTC temperature exerted a more significant effect on the fuel properties of hydrochar samples than HTC duration did, which also indicated by their subsequent thermochemical conversion. These findings can provide essential knowledge on the thermochemical conversion of hydrochar samples and favor the designing, optimization, and scaling up of the process.

关键词： Sewage sludge Hydrothermal carbonization Hydrochar Gasification Kinetics Volatiles

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Acoustic tomography of two dimensional velocity field by using meshless radial basis function and modified Tikhonov regularization method

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MEASUREMENT 2021年 175卷 109107-109107页

作者： Zhang, Juqi Qi, Hong Jiang, Donghang He, Mingjian Ren, Yatao Su, Mingxu Cai, Xiaoshu Harbin Inst Technol Sch Energy Sci & Engn Harbin 150001 Peoples R China Minist Ind & Informat Technol Key Lab Aerosp Thermophys Harbin 150001 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China

A meshless radial basis function (RBF) method combined with the modified Tikhonov regularization is proposed to reconstruct the two-dimensional velocity field. Time-of-flight data is obtained to capture the flow information of the region of interest. Three kinds of RBFs are employed to acquire the coefficient matrix of the AT. It also adds the prior information of continuity into the flow field reconstruction. Modified Tikhonov regularization is introduced to reconstruct the velocity field which alleviates the severe ill-posedness of the acoustic tomography (AT) problem. The influence of shape parameters, types of RBF, and the collocation of central points on reconstruction are investigated. Proof-of-concept simulations and corresponding Tomographic PIV data based simulation verification are conducted to prove the feasibility and effectiveness of the proposed method in velocity field reconstruction. All these results confirm that it is appropriate to solve severely ill-posed and underdetermined AT problems and in recovering the velocity field distribution.

关键词： Acoustic tomography Time of flight Radial basis function Velocity measurement Tikhonov regularization

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Green synthesis of Tungsten-doped CeO2 catalyst for selective catalytic reduction of NOx with NH3 using starch bio-template

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APPLIED SURFACE SCIENCE 2021年 536卷 147719-147719页

作者： Xiong, Zhi-bo Li, Zhen-zhuang Li, Cheng-xu Wang, Wei Lu, Wei Du, Yan-ping Tian, Su-le Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Shanghai Jiao Tong Univ China UK Low Carbon Coll Shanghai 200240 Peoples R China Shandong Elect Power Engn Consulting Inst Corp Lt Jinan 250013 Peoples R China

Herein, a novel tungsten-doped CeO2 catalyst was fabricated via the spread self-combustion (SSC) method using sweet potato starch as bio-template. The doping of tungsten refines the pore diameter of CeO2 and restrains the growth of cubic CeO2 crystal formed in it. However, the annealing at 700 degrees C promotes the growth of cubic CeO2 crystal and the formation of Ce4W9O33 crystal instead of the amorphous tungsten species compared with the catalyst calcined at 550 degrees C. It is also found that the doping of tungsten increases the concentration of the adsorbed oxygen on the surface of CeO2-550 and enhances the reducibility of the surface oxygen of stoichiometric ceria and the acid sites. The as-prepared Ce4W2Oz-550 catalyst exhibits higher catalytic performance than Ce4W2Oz-CP-550 synthesized via the urea hydrothermal co-precipitation method due to the better dispersion of cerium species and the larger molar ratio of O-alpha/(O-alpha + O-beta). However, the enhancement of annealing temperature from 550 degrees C to 700 degrees C decreases the acidic and the redox properties of Ce4W2Oz, and thereby depresses the promotional effect of tungsten-doped on the NH3-SCR activity of CeO2-550. The suitable starch dosage (liquid/solid ratio), ion concentration, alkali titration and annealing temperature are 1 g (10 mL/g), 1 mol/L, ammonia water (pH approximate to 7.0) and 400-550 degrees C for the as-prepared Ce4W2Oz catalyst, respectively.

关键词： Catalyst Selective catalytic reduction of NOx Cerium oxide Starch bio-template Tungsten-doped

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Spatial-angular spectral element method with discontinuous Galerkin schemes for radiative transfer in 2D irregular enclosures with obstacles based on unstructured spatial elements

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JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE transfer 2022年 280卷 108082-108082页

作者： Sun, Yasong Li, Sida Zhou, Ruirui Guo, Zhixiong Ma, Jing Northwestern Polytech Univ Sch Power & Energy Shaanxi Key Lab Thermal Sci Aeroengine Syst Xian 710072 Peoples R China Yangtze River Delta Res Inst NPU Ctr Computat Phys & Energy Sci Taicang 215400 Peoples R China Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Rutgers State Univ Dept Mech & Aerosp Engn Piscataway NJ 08854 USA Changan Univ Sch Automobile Key Lab Shaanxi Prov Dev & Applicat New Transport Xian 710064 Peoples R China

In the article, we propose a spectral element method with discontinuous Galerkin schemes (SEDG) for solving radiative transfer problems in irregular enclosures with obstacles. The SEDG is used to discretize both angular and spatial domains. In the spatial domain, unstructured triangular elements with spectral collocation points are adopted to discretize the irregular enclosure with obstacles. In the angular direction, the structured quadrilateral elements with spectral collocation points are used, and a parallel computing strategy is employed to improve the computational efficiency. To smoothen the oscillations induced by the discontinuity in the spatial distribution of radiative intensity due to obstacle, an upwind approximate Reimann solver is developed to separate the incoming and outgoing information of radiative intensities on spatial element boundaries. Three examples are chosen to test the capability of the SEDG. Results demonstrate that the SEDG can flexibly provide hp convergence characteristics. Meanwhile, it can effectively minimize the non-physical oscillation in the spatial domain and angular direction, and can obtain the high angular resolution of radiative intensity. (c) 2022 Elsevier Ltd. All rights reserved.

关键词： Spectral element method Discontinuous Galerkin scheme Radiative transfer Complex geometry Obstacle

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Experimental investigation of Zhundong high-calcium coal ash adhesion characteristics on metal surfaces at high temperatures

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ASIA-PACIFIC JOURNAL OF CHEMICAL engineering 2021年第6期16卷 e2705-e2705页

作者： Liu, Zhongyi Jin, Jing Zheng, Liangqian Yang, Haoran He, Xiang Zhai, Zhongyuan Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai Peoples R China Shanghai Marine Diesel Engine Res Inst Environm Equipment Dept Shanghai Peoples R China Shanghai Power Equipment Res Inst Co Ltd Thermal Power Technol Res Ctr Shanghai Peoples R China Shanghai Boiler Works Co Ltd Design Dept Shanghai Peoples R China

Herein, the influence of ash adhesion characteristics on the slagging of Zhundong high-calcium coal (ZDc) has been firstly investigated via a self-designed measuring instrument. The results demonstrate that the early appearance and rapid growth in adhesion strength of ZDc ash are the important reasons for its serious slagging in the furnace, and the temperature plays an important role on the adhesion between ZDc ash and metal. From 800 degrees C to 1000 degrees C, the adhesion strength of ZDc gradually increases from 1.858 to 21.725 kPa. Meanwhile, the adhesion strength could increase rapidly due to the production of more liquid phase when the temperature exceeds 1000 degrees C, and the adhesion strength is 184.933 at 1200 degrees C. The calculation results via FactSage software also indicates that molten sulfate is the main component of liquid-phase ash and the enhancement of the CaO content contributes to promote the low-temperature eutectic of gehlenite, etc., thereby enhances the strengthen of the adhesion.

关键词： ash adhesion strength calcium oxide liquid content molten sulfate Zhundong high-calcium coal

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A Self-generated Chemotaxis-inspired routing method for digital microfluidic cooling of hotspots in integrated circuits

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ENERGY CONVERSION AND MANAGEMENT 2022年 266卷

作者： Chen, Maohua Chen, Senlong Liao, Ming Jin, Mingliang Zhao, Yugang Zhou, Guofu Shui, Lingling Yan, Zhibin South China Normal Univ South China Acad Adv Optoelect Guangdong Prov Key Lab Opt Informat Mat & Technol Guangzhou 510006 Peoples R China South China Normal Univ Inst Elect Paper Displays South China Acad Adv Optoelect Guangzhou 510006 Peoples R China South China Normal Univ Sch Informat & Optoelect Sci & Engn Guangzhou 510006 Peoples R China Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

Effective thermal management is of great significance for the reliability of the high-density-power electronics such as the three-dimensional integrated circuits (3DICs). Cooling method based on digital microfluidic (DMF) driven by electrowetting-on-dielectric (EWOD) has been regarded as a promising solution to the effective thermal management of 3DICs. Compared with other traditional cooling methods, DMF has advantages of lower power consumption and especially adaptive cooling ability which can achieve accurate cooling for hot spots inside the 3DICs. However, there are hardly any researches investigating into the droplet routing methods for DMF cooling systems. In this paper, we propose a droplet route optimization method inspired by the self-generated chemotaxis which aims to achieve real-time and parallel routing for multiple coolant droplets to search and cool hot spots. Based on the proposed thermal model of integrated circuit and DMF cooling system, various cooling cases have been simulated with different configurations (e.g., the cooling route and the inlet number). Numerical results show that the proposed self-generated chemotaxis-inspired algorithm (SCA) is capable of searching multiple hot spots based on the real-time temperature profiles and realizing multiple droplets routing simultaneously (i.e., parallel routing and cooling). Compared with traditional ant-colony-algorithm route and direct route, the SCA route provides the best temperature mitigation performance in appropriate inlet-configuration, and its cooling performance can be further improved as the inlet number increases.

关键词： three-dimensional integrated circuits (3DICs) Hot spots Digital microfluidics Route optimization Adaptive chip cooling

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Effective immobilization of nanoscale Pd on a carbon hybrid for enhanced electrocatalytic performances: stabilization mechanism investigations

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NANOSCALE 2019年第45期11卷 21934-21942页

作者： Yang, Liang Liu, Daoping Cui, Guomin Dou, Binlin Wang, Juan Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Sch Energy & Power Engn 561 Jungong Rd Shanghai 200093 Peoples R China Shanghai Univ Elect Power Sch Environm & Chem Engn 2588 Changyang Rd Shanghai 200090 Peoples R China

The grand challenge inhibiting the use of electrocatalysts is the degradation of active species which results in poor durability and long-term performances. Studying the origin of active metal particle stabilization mechanisms by using supports and the immobilization-induced changes of active particles is of significant importance. This study describes the preparation of Pd nanoparticles supported by carbon hybrid NPG-CN, revealing that the mass and specific activities (1987 A g(-1) Pd and 28.7 A m(-2)) of this catalyst for formic acid oxidation significantly exceed those of commercial Pd/C, and excellent stability and enhanced CO-poisoning tolerance properties are obtained. The origin of this behavior is probed by surface analytical techniques and identical-location transmission electron microscopy (IL-TEM), and the enhanced activity of Pd/NPG-CN is ascribed to the electronic effect of the substrate, the high content of surface metallic Pd-0, and the reduced extent of active Pd leaching and physical ripening during the FOA process compared with commercial Pd/C. In addition, theoretical calculations demonstrate that NPG-CN can efficiently trap Pd atoms, which accumulate and form Pd clusters at trapping (nucleation) sites.

关键词： Electrocatalysts

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Effect of HCl and o-DCBz on NH3-SCR of NO over MnOx/TiO2 and MnOx-CeO2/TiO2 catalysts

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APPLIED CATALYSIS A-GENERAL 2020年 605卷 117801-117801页

作者： Wang, Qiulin Lin, Feng Zhou, Jianjian Zhang, Jianchao Jin, Jing Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

A novel selective catalytic reduction (SCR) catalyst with strong chlorine resistance ability is urgently needed to extend the catalyst life, when SCR technique is applied in plants with high chlorine content (e.g. municipal solid waste and medical waste incinerators). This study investigates the influences of typical chlorine-containing inorganic/organic compounds (i.e. hydrogen chloride (HCl) and o-dichlorobenzene (o-DCBz)) on NH3-SCR of NO over MnOx/TiO2 and MnOx-CeO2/TiO2 catalysts at low temperatures (100 - 250 degrees C). The results indicate the presence of HCl severely inhibits the NH3-SCR reaction. On one hand, the reaction between NH3 and HCl causes the deposition of NH4Cl on catalyst surface and reduces the amount of NH3;on the other hand, HCl consumes the surface acid sites which is essential to the adsorption and activation of NH3;moreover, chlorine (Cl) atom prefers to anchor on the uncoordinated metal sites that restrains the regeneration of surface reactive oxygen species and interrupts the redox cycle of catalysts. Ce addition enhances the chlorine resistance property of MnOx-CeO2/TiO2 catalyst by interacting with HCl preferentially. The negative effect of o-DCB on NH3-SCR reaction is more serious than that of HCl below 200 degrees C. That's because the competitive effect between o-DCB catalytic oxidation and deNO(x) via NH3-SCR reaction as well as the accumulation of o-DCB incomplete oxidation byproducts on catalyst surface further aggravates the catalyst deactivation induced by Cl atom.

关键词： NH3-SCR MnOx-based catalyst Chlorine poisoning Ce addition Effect of o-DCBz

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Competition between reduction reaction and carbon deposition for CaSO₄ oxygen carrier in chemical-looping combustion: A first-principle study and reaction equilibrium analysis

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SURFACES AND INTERFACES 2021年 25卷

作者： Hou, Fengxiao Jin, Jing Liu, Dunyu Kou, Xuesen Yang, Haoran Wang, Yongzhen Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Linyi Univ Sch Civil Engn & Architecture Linyi 276000 Shandong Peoples R China

To understand the reaction mechanism of chemical looping combustion with calcium-based oxygen carrier, the competition mechanisms between reduction reaction and carbon deposition for CaSO4 oxygen carrier were calculated by density functional theory and simulated by chemical reaction equilibrium analysis. In this paper, the reaction paths of reduction reaction and carbon deposition at different CaSO4(010) surface outer oxygen content (100%, 75%, 50%, 25%) were studied, and the reversibility of the reaction was fully considered. Furthermore, based on the kinetic analysis of the transition state theory, the kinetic parameters of the elementary reaction were obtained. Moreover, the reaction equilibrium simulation revealed the competition of reactions under different conditions. The results show that the energy barriers of forward and reverse reactions decrease with the oxygen content decreasing on the CaSO4 (010) outer layer surface in the reduction reaction. Besides, the forward energy barriers at each stage are lower than the reverse energy. In the carbon deposition reaction, the energy barriers of the forward reaction are higher than the reverse reaction, and the energy barriers of the reverse reaction gradually increase with oxygen content decreasing. The kinetic analysis results show the ratelimiting steps of forward and reverse reaction in reduction reaction are 75% and 25% oxygen content stage. According to the reaction equilibrium, the conversion rate of CO oxidation to CO2 decreases with temperature increasing, and the conversion rate of carbon deposition increases. The rate of CO oxidation to CO2 increase and the occurrence of carbon deposition reaction decrease with oxygen carrier ratio increasing. Thus, when the oxygen carrier is insufficient or most of CaSO4 is reduced, the carbon deposition reaction occurs easily.

关键词： Chemical-looping combustion Heterogeneous reaction Carbon deposition Kinetic analysis Reaction equilibrium

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Freezing of a nanofluid droplet: From a pointy tip to flat plateau

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APPLIED PHYSICS LETTERS 2021年第14期118卷 141602-141602页

作者： Zhao, Y. Yang, C. Cheng, P. Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China China Aerodynam Res & Dev Ctr Key Lab Icing & Anti Deicing Mianyang 621000 Sichuan Peoples R China Nanyang Technol Univ Sch Mech & Aerosp Engn Singapore 639798 Singapore Shanghai Jiao Tong Univ Sch Mech Engn MOE Key Lab Power Machinery & Engn Shanghai 200240 Peoples R China

Understanding the dynamics during freezing of nanofluid droplets is of importance from both fundamental and practical viewpoints. It is known that a universal pointy tip is formed on the top of a frozen water droplet [Marin et al., Phys. Rev. Lett. 113(5), 054301 (2014)]. Here, we report that the formation of a pointy tip is broken down due to the presence of nanoparticles;instead, the top of a frozen nanofluid droplet exhibits a flat plateau shape and such a plateau becomes larger at higher particle concentrations. We show that the phenomenon of such shape changes in freezing nanofluid droplets is universal, independent of contact angle, droplet volume, particle size, and particle material. We propose an analytical model to attribute the plateau formation to a capillary driven compensating flow due to segregated particles moving along the freezing interface.

关键词： Drops

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