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Fabrication of methane thermoelectric gas sensor based on 3D porous Pd/Co3O4 catalyst

JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY 2020年第9期95卷 2403-2410页

作者： Sun, Li Li, Chuanliang Zhang, Hua Dou, Binlin Su, Wenxian Zhang, Lixin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Jun Gong Rd 516 Shanghai 200093 Peoples R China

BACKGROUND At present, much attention has been focused on the development of methane (CH4) sensors due to a series of explosions and fires caused by CH4 gas leakage. RESULTS Here, a CH4 thermoelectric gas sensor (TGS) was fabricated by fixing 3D porous palladium/cobalt oxide (Pd/Co3O4) catalyst on a commercial thermoelectric module. 3D porous Pd/Co3O4 catalysts were prepared by a co-precipitation and gel-casting method. The pore structure in catalysts could be tailored only by adjusting the gel viscosity during the formation process. The protocol to tune the pore structure is facile and effective for the improvement of the activity of catalysts. By means of various techniques, the catalysts were characterized and then the possible catalytic mechanism was revealed. The CH4 TGS based on the optimal Pd/Co3O4 catalyst began to respond at 200 degrees C, following an obvious output voltage (Delta V) of 5 mV. Enhancing the operating temperature to 240 degrees C, the value of Delta V reached to 31 mV and exhibited a linear relationship with CH4 gas concentration. Meanwhile, the CH4 TGS showed high sensitivity, repeatability and stability. CONCLUSION The easy and effective preparation method presented to prepare 3D porous Pd/Co3O4 catalyst can provide an unique perspective on the development of 3D porous materials with excellent properties. It can be anticipated that the CH4 TGS based on the 3D porous Pd/Co3O4 catalyst will be a potential candidate for the detection of CH4 gas in industrial settings. (c) 2020 Society of Chemical Industry

关键词： methane sensor Pd Co3O4 catalyst co-precipitation method gel-casting method

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Experimental investigation on system performances and transient response of a pumped two-phase battery cooling system using R1233zd

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ENERGY REPORTS 2020年 6卷 238-247页

作者： Fang, Yidong Ye, Fei Zhu, Yue Li, Kang Shen, Jiali Su, Lin Univ Shanghai Sci & Technol Coll Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

This study presents an experimental investigation on the pumped two-phase cooling system designed for battery thermal management. The experimental system was established with R1233zd as the refrigerant, and a dummy battery was used to simulate the heat generation during battery operation. The thermodynamic cycle, wall temperature distribution of the cold plate and overall heat transfer coefficient were analyzed under steady state, while the transient response of the system with pump control was also studied. Results showed that the evaporating pressure of the system was not sensitive to the refrigerant mass flux, while it could be raised under higher heating loads. Both the refrigerant mass flux and vapor quality at the cold plate outlet showed little influence on the wall temperature distribution of the cold plate, however their effects on the overall heat transfer coefficient were different. An optimum value of vapor quality at cold plate outlet could be found for the pumped two-phase cooling system to achieve a maximum heat transfer coefficient. Based on this feature, a pump control program was designed and embedded into the system, and transient experiment showed that the control program could effectively handle the sharp increase of heating load. The application of the control program could lead to a near 10 K decrease in wall temperatures of the cold plate by maintaining the outlet vapor quality of the cold plate at 0.25 when the heating load was instantly raised from 100 W to 600 W, meanwhile the growth of wall temperature was also slower. The results of this study can serve as a guideline for the application of pumped two-phase cooling system on battery thermal management. (C) 2020 The Author(s). Published by Elsevier Ltd.

关键词： Pumped two-phase cooling Battery thermal management Thermal performance Transient response

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Study of a novel ceramsite-based shape-stabilized composite phase change material (PCM) for energy conservation in buildings

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CONSTRUCTION AND BUILDING MATERIALS 2020年 246卷 118479-000页

作者： Yang, Yingying Wu, Weidong Fu, Shunyu Zhang, Hua 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

Building envelope with phase change material (PCM) embedded is able to optimize the thermal utilization and reduce energy consumption in buildings. However, the leakage of molten PCM, the low thermal performances (latent heat and thermal conductivity) and the inappropriate melting temperature limit the application of PCM in buildings. This work aims to propose a novel shape-stabilized composite PCM with encouraging thermal performances and effective encapsulation for applying to the building envelope. Firstly, a binary PCM with appropriate thermal properties for buildings was studied by using lauryl alcohol, stearic acid and nanoparticles, marked as LA-SA/Al2O3. Then this prepared LA-SA/Al2O3 was absorbed into ceramsite and encapsulated by styrene-acrylic emulsion and dry cement powder for shape-stability, a ceramsite-based PCM (LA-SA/Al2O3/C) was formed. Finally, the thermal-physical performances of the mixture of LA-SA/Al2O3/C and concrete were tested. The thermal performances of LA-SA/Al2O3 and LASA/Al2O3/C were measured by differential scanning calorimetry (DSC), the chemical and thermal stabilities were tested by Fourier transform infrared (FT-IR) and thermogravimetric (TG). Results show that the optimal proportion for LA-SA/Al2O3 is 82 wt% LA + 18 wt% SA with 0.5 wt% Al2O3 nanoparticle, for which the melting temperature and latent heat are 21.3 degrees C and 205.9 kJ/kg respectively. The LA-SA/Al2O3/C has the ability to prevent the leakage of PCM, owning the excellent melting latent heat of 133.4 kJ/kg, which is relatively high comparing with the values in other references. The concrete based-CPCM with 15% LA-SA/Al2O3/C embedded shows satisfied mechanical performance and has great potential to reduce the indoor temperature fluctuation caused by outdoor ambient, and cut down the energy consumptions of heating and cooling devices in buildings. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： PCM Ceramsite Shape-stabilized PCM Concrete Building envelope

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Molecular dynamics simulation of the wetting characteristics of a nanofluid droplet on rough substrate

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JOURNAL OF MOLECULAR LIQUIDS 2020年 319卷 114204-114204页

作者： Wang, Zhao Li, Ling Yang, Mo 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

Wettability of a nanofluid droplet (ND) on rough substrate with fence pattern was researched by molecular dynamics (MD) method. The Embedded Atom Method (EAM) potential was used to model the interatomic interaction between nanoparticle atoms, solid rough substrate atoms and between these two. The effects of the surface morphology of substrate, the surface wettability of the nanoparticle, and the nanoparticle volume fraction (NVF) on the wettability of ND were studied. The vapor-liquid surface tension and viscosity of nanofluid were also discussed in details. The results show that the initial equilibrium contact angle (theta(e)) of ND on a rough substrate is larger than that on a smooth substrate. When the interaction parameter between the substrate atoms and oxygen atoms increases, theta(e) decreases. For hydrophilic rough substrates, the larger the NVF of hydrophilic nanoparticles in the ND, the greater the equilibrium contact angle of the ND, and the worse the wetting properties of the ND, which determines that the main driving force for the dynamic spreading process of the ND is the vapor-liquid surface tension and viscosity of the ND. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Nanofluid droplet Wettability Rough substrate NVF Surface tension Viscosity

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Influence of large seed particle on acoustic particle interaction dynamics: A numerical study

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JOURNAL OF AEROSOL SCIENCE 2022年 165卷

作者： Yang, Nana Fan, Fengxian Hu, Xiaohong Su, Mingxu Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

Acoustic agglomeration as a promising preconditioning process for fine particle removal has been proven to be inefficient for submicron particles. In order to enhance the performance of acoustic agglomeration, large seed particles have been introduced into the flue gas. To understand the influence of seed particles on acoustic agglomeration, a nondimensional model of particle interaction was developed by taking into account all important particle interaction mechanisms. The simulated particle trajectories were validated against experimental data. The interaction dynamics of a seed particle and its neighboring fine particles was examined, and the dimensionless first collision time under different conditions was obtained. The results suggest that the enhancement of acoustic agglomeration with seed particle is mainly due to the acoustic wake effect. The overall collision kernel for the acoustic agglomeration was referred from the collision time. The results reveal that the dimensionless collision kernel almost increases linearly with the Stokes number of the seed particle, whereas its dependence on the Schmidt number of the fine particle varies significantly. The collision kernel for acoustic agglomeration was further compared with traditional collision kernels based on differential sedimentation, Brownian diffusion, laminar shear and turbulent shear. The results demonstrate that acoustic field indeed remarkably enhances the collision rate.

关键词： Acoustic agglomeration Particle interaction Collision kernel Fine particle Seed particle Numerical simulation

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Assessment method of the integrated thermal management system for electric vehicles with related experimental validation

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ENERGY CONVERSION AND MANAGEMENT 2023年 276卷

作者： Li, Kang Chen, Hongming Xia, Dingyu Zhang, Hanqi Dou, Binlin Zhang, Hua Liu, Ni Su, Lin Zhou, Xuejin Tu, Ran Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Key Lab Multiphase Flow & Heat Transfer Shanghai P Shanghai 200093 Peoples R China Huaqiao Univ Coll Mech Engn & Automat Xiamen 361021 Fujian Peoples R China

Concerns about the driving ranges of electric vehicles (EV) have led to higher requirements for vehicle thermal management systems. Efficient thermal management systems should be closely integrated with the vehicle to ensure passenger comfort and maintain adequate component operating ranges. The thermal management functions should thus accurately meet the demands of the EV and its components. Based on the driving conditions for EVs and the component thermal management requirements, this study applies different working modes for the cabin, power battery, electric motor, and electric motor controller systems under various conditions, which combines these modes into 27 feasible system working modes. Subsequently, an integrated thermal management system is designed with multi-modes adjusted by each system component to adapt environmental variations by changing the system's working mode. Also, the energy exchange between components under different modes was investigated to ensure the rationality of the designed system. The best working mode is to ensure the safety and comfort for EVs with fewer components and lower cost. It was proved to meet a wide range of adaptations to environmental changes that can be used as a method to evaluate the integrated thermal management system. The method is then applied to the target thermal management system and proves that the target system offers considerable advantages over two other benchmark thermal management systems that have been used in the mass production of electric vehicles. Finally, the cooling, heating, and defrosting performances are verified experimentally, and the vehicle mileage is calculated. The thermal management system working modes are summarized systematically. The designed thermal management system is a waste heat recovery steam compression heat pump system that can meet the functional and experimental test requirements. This study verifies that the heat management system evaluation method can evaluate the system

关键词： Electric vehicle Thermal management Assessment method heat pump air conditioning system

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On-line measurement of ultralow mass concentration particulate based on light scattering coupled with beta ray attenuation method

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FUEL 2022年 329卷

作者： Huang, Yubo Liu, Xiaowei Wang, Zhaofeng Jiang, Meng Zhou, Zijian Xu, Minghou Han, Jinke Yang, Bin Fan, Xinfeng Huazhong Univ Sci & Technol Sch Energy & Power Engn State Key Lab Coal Combust 1037 Luoyu Rd Wuhan 430074 Peoples R China JX Energy Technol Res Inst Nanchang 330000 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Wuhan Tianhong Environm Protect Ind Co Ltd Yuhong Environm Protect Sci & Technol Ind Pk 11 Huashiyuan North Rd Wuhan 430074 Peoples R China

Light scattering method is the most commonly used method for on-line measurement of ultralow particulate matter mass concentration. However, when the particle characteristics change, the effectiveness of the empirical relationship decreases, which would lead to a sizeable deviation. To accurately measure the mass concentration of particulate matter in real-time, a coupling measurement idea of light scattering and beta-ray attenuation is proposed. The beta-ray attenuation is little affected by particle properties and accurately reflects the average PM mass concentration in the measured period. The single calibration method (M1), periodic calibration method (M2), average calibration method (M3), and asymmetric factor calibration method (M4) are formed based on the coupling idea. The results of all methods are perfect when the particle size is unchanged. However, when the particle sizes fluctuate frequently, the results of M1, M2, and M3 deviate seriously from the actual value, and the applicable working conditions have limitations. The results of M4 are in good agreement with the actual value, and the effectiveness is not limited by the particle size. Finally, the prototype based on experimental exploration was developed and had been continuously operated for more than 528 h at a 1000 MW unit of a coal-fired power plant.

关键词： Light scattering Beta -ray attenuation Coupling method Particle size

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Calculation of internal heat source and thermal gradient of cylindrical traction battery with measured surface temperature and heat flux

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INTERNATIONAL JOURNAL OF THERMAL SCIENCES 2023年第1期187卷

作者： Wang, Haimin Zhu, Zexu Ji, Zhiyuan Hu, Feng Lin, Hao Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Dongfeng Commercial Vehicle Co Ltd Dongfeng Commercial Vehicle Tech Ctr Wuhan 430056 Peoples R China

In the process of charging and discharging, the traction battery not only experiences electrochemical reactions, but also includes many side reactions, the typical phenomenon of which is the rise of battery temperature. In order to study the characteristics of the internal heat source and the distribution of the temperature field of a cylindrical battery, a one-dimensional (radius direction) heat transfer model is established in this work. Then, the temperature and heat flux measured on the external surface of the battery is used to calculate the internal heat source and temperature distribution, so as to quantify the thermal gradient in the diameter direction. In order to verify the feasibility of the model, a small incision is cut at the bottom of the battery, a thermocouple is built in to measure the temperature of the central position inside the battery, and the measured temperature is compared with the calculated temperature. The results show that the calculated results of the model have high reliability. In addition, the proposed model is also used to calculate the temperature of its internal central position at a higher ambient temperature (40 degrees C) and a lower ambient temperature (-10 degrees C). It is found that the calculated results are very close to the measured results at the ambient temperature of 40 degrees C, but the difference between the two was large at the ambient temperature of-10 degrees C.

关键词： Traction battery heat flux Thermal gradient Temperature inversion algorithm

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Measurement of bubble/slug velocity and size in vertical pipe based on optical cross-correlation method

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OPTIK 2023年 272卷

作者： Yang, Bin Wang, Wensong Ping, Li Pei, Chenxi Chen, Xiaolong Wang, Ying Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Shanghai Space Prop Technol Res Inst Shanghai 201109 Peoples R China Shanghai Inst Proc Automat & Instrumentat Co Ltd Shanghai 200233 Peoples R China

Based on the principle of the cross-correlation, the method for measuring the velocity and size of bubbles in transparent gas-liquid two-phase flow in a vertical pipe is proposed by taking optical attenuation signal as the object. This method is used to measure the bubble velocity and size of transparent gas-liquid two-phase flow in vertical pipeline of two-phase flow experimental platform, and compared with synchronous measurement by image method. The experimental results show that the relative deviation of velocity and size between optical cross-correlation measurement and image method is less than 3% and 5%, respectively. The optical cross-correlation method can be used to measure the bubble velocity and size parameters of transparent gasliquid two-phase flow in the vertical pipe without contact, and this method is suitable for industrial applications.

关键词： Bubble slug measurement Optical cross -correlation method Velocity and size measurement Image method Gas -liquid two-phase flow

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Hygroscopicity of aerosol particles composed of surfactant SDS and its internal mixture with ammonium sulfate at relative humidities up to 99.9%

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ATMOSPHERIC ENVIRONMENT 2023年第1期298卷

作者： Zhang, Chao Lu, Miaoran Ma, Nan Yang, Yang Wang, Yueshe Groess, Johannes Fan, Zhaoxia Wang, Mengyao Wiedensohler, Alfred 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 Jinan Univ Inst Environm & Climate Res Guangzhou 511443 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Leibniz Inst Tropospher Res D-04318 Leipzig Germany

For atmospheric aerosol particles, the ubiquitous surfactants can significantly influence their hygroscopicity. However, the hygroscopicity of nanoscale particles containing surfactants are not well understood under sub -saturated conditions, especially at high relative humidity (RH = 90-100%), due to the limitation of traditional instruments and the diversity of surfactants. Here, the hygroscopicity of nanoscale particles composed of a strong surfactant sodium dodecyl sulfate (SDS) and its mixture with ammonium sulfate (AS) was measured using the high humidity tandem differential mobility analyzer (HHTDMA) at RH up to about 99.9%. Three different models based on Ko spacing diaeresis hler theory but different representations of surfactant characteristics were employed to reproduce the measurement outcomes. Results show that SDS particles start gradual hygroscopic growth after RH reaching 97.5%. For SDS-AS mixed particles with 25% w/w SDS, prompt deliquescence and gradual deliques-cence are observed for smaller (20 and 40 nm) and larger particles (100 and 200 nm), respectively. For particles with >= 50% w/w SDS, the onset deliquescence is difficult to found. In general, the model that comprehensively accounts for the surfactant properties including bulk-to-surface partitioning, surface tension reduction, micel-lization and the effect of RH on hygroscopicity parameter, kappa (for SDS-AS particles) provides the best predictions for the experimental hygroscopicity of SDS and SDS-AS particles at subsaturation conditions. Besides, factors affecting the accuracy of theoretical model are discussed in detail. The kappa derived from subsaturated measurement is strongly dependent on RH and dry diameter.

关键词： Aerosol particles Surfactant Hygroscopicity High relative humidity Bulk -to -surface partitioning

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