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Experimental Investigation on flow and Heat Transfer Characteristics of Helium in Rectangular Narrow Slit Channel

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SSRN 2024年

作者： Li, Changzhong Wang, Chenglong Sun, Yanyu Chen, Ronghua Tian, Wenxi Su, Guanghui Qiu, Suizheng State Key Laboratory of Multiphase Flow in Power Engineering China Department of Nuclear Science and Technology Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China China Nuclear Power Engineering Co. Ltd. Beijing100840 China

Helium is utilized as coolant in high temperature gas cooled reactors. Rectangular narrow slit channels are commonly present in the core. The flow and heat transfer properties of helium significantly affect the core temperature and flow distribution. This paper experimentally investigates the flow and heat transfer properties of high temperature helium in rectangular narrow slit channel. The Reynolds numbers ranged from 468 to 5327, the temperature ratio of wall to bulk from 0.91 to 1.22, the helium outlet temperature up to 944 K, and the maximum heat flux density up to 0.101 MW/m². In the experiment, the total and local convective heat transfer coefficients, along with the friction factors, are measured. Correlation equations for the Nusselt number and friction factor with respect to Reynolds number are derived. The primary findings are as below: the friction factors of helium in rectangular narrow slit channels are significantly larger than those calculated by current empirical correlations. In the turbulent zone, the measured local Nusselt numbers are in excellent accordance with the Gnielinski correlation;however, a significant discrepancy exists in the laminar zone. New flow heat transfer correlation equations are proposed on the bases of experimental data. Upon comparison, the total Nusselt numbers fall in the error of 10%, and almost all local Nusselt numbers and the friction factors fall in the error of 20%. © 2024, The Authors. All rights reserved.

关键词： Helium

A new strategy to produce calcium carbide-acetylene from integrated multi-level low carbon construction driven by biomass

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A new strategy to produce calcium carbide-acetylene from int...

作者： Wang, Hongxia Li, Xiaoli Wu, Zhen Shen, Wei Chen, Kai Hong, Bingqing Zhang, Zaoxiao School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow in Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi'an710049 China Co. Ltd Level 10-15 Block A Sunland International No.999 Zhouhai Road Pudong New Zone Shanghai200131 China

A highly efficient and clean biomass energy-based calcium carbide-acetylene production system, including low-carbon energy supply, solid waste recycling and cascade utilization of waste heat, has been developed for the conventional energy-intensive and highly polluting fossil fuel-dependent calcium carbide industry. This system supplies the carbide-acetylene production plant with energy from the gasification of biomass and converts the plant's solid waste carbide slag into the calcium feedstock required by the plant. The waste heat from the plant's high-temperature exhaust gases is recycled and used via the multi-stage heat exchange, so that the energy cascade conversion and utilization is achieved. A simulation model of the plant is created in Aspen Plus, and a mathematical model for the biomass gasification process and cycle compensation of the calcium source through the Fortran language is written and embedded. When calculating the carbon consumption and CO2e emissions of the system, it was found that the carbon consumption and CO2e emissions of the conventional process were 5.43 t Coal·t−1C2H2 and 2.25 t CO2e·t−1C2H2, respectively. However, the carbon consumption of the new process was reduced by 65.19%, and carbon emissions by 27.24% in comparison. The energy analysis shows that the energy efficiency of the system is 36.21% for the conventional process and 44.82% for the new processes. The exergy analysis of the effective energy shows that the exergy efficiency of the new process is 73.20%, which is 52.98% better than that of the conventional process. Introduction of an index, the levelized income of acetylene product (LIOA), to characterize the product income of the system. When the price of acetylene is between 2.23 $/kg and 4.19 $/kg, the LIOA for the conventional and the new processes are 1.41 $/kg to 3.38 $/kg and − 1.28 $/kg to 0.68 $/kg, respectively. It is worth noting that the critical price (PCC2H2) for products generating net revenue from the new pro

关键词： Biomass

Analysis of fracture propagation and shale gas production by intensive volume fracturing

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Applied Mathematics and Mechanics(English Edition) 2023年第8期44卷 1385-1408页

作者： Qingdong ZENG Long BO Lijun LIU Xuelong LI Jianmeng SUN Zhaoqin HUANG Jun YAO College of Energy and Mining Engineering Shandong University of Science and TechnologyQingdao 266590Shandong ProvinceChina Research Center of Multiphase Flow in Porous Media China University of Petroleum(East China)Qingdao 266580Shandong ProvinceChina State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu 610500China College of Energy Chengdu University of TechnologyChengdu 610059China College of Geoscience China University of Petroleum(East China)Qingdao 266580Shandong ProvinceChina

This paper presents an integrated study from fracture propagation modeling to gas flow modeling and a correlation analysis to explore the key controlling factors of intensive volume *** fracture propagation model takes into account the interaction between hydraulic fracture and natural fracture by means of the displacement discontinuity method(DDM)and the Picard iterative *** shale gas flow considers multiple transport mechanisms,and the flow in the fracture network is handled by the embedded discrete fracture model(EDFM).A series of numerical simulations are conducted to analyze the effects of the cluster number,stage spacing,stress difference coefficient,and natural fracture distribution on the stimulated fracture area,fractal dimension,and cumulative gas production,and their correlation coefficients are *** results show that the most influential factors to the stimulated fracture area are the stress difference ratio,stage spacing,and natural fracture density,while those to the cumulative gas production are the stress difference ratio,natural fracture density,and cluster *** indicates that the stress condition dominates the gas production,and employing intensive volume fracturing(by properly increasing the cluster number)is beneficial for improving the final cumulative gas production.

关键词： fracture network propagation shale gas fow intensive volume fracturing displacement discontinuity method(DDM) embedded discrete fracture model(EDFM)

Sensitively Detection of Ascorbic Acid in Orange Samples with Ionic Liquid Functionalized Carbon Dots and Lanthanide Complexes

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SSRN 2024年

作者： Li, Ying Xia, Ji-Ji Lu, Jia-Zhen Wang, Zi-Long Wang, Mi-Tang School of Materials and Chemistry University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China

In the food industry, ascorbic acid (AA) is widely used as an antioxidant. However, the concentration of AA is influenced by various factors, including temperature, time, and pH value during food preparation and storage, leading to its instability in content. This makes the accurate detection of AA content particularly important. Precise determination of AA content in food and pharmaceuticals is crucial for ensuring the adequate intake of essential vitamins and maintaining good health. Herein, we have developed a successful preparation method of an imidazole-based ionic liquid functionalized CDs hybrids APM-CDs. A novel photo functional hybrid probe Eu3+@APM-CDs was obtained via an ion-exchange reaction between APM-CDs and lanthanide complex Eu(DPA)3. The obtained hybrid probe was extensively characterized in detail. What’s more, the results show that the FL intensity of Eu3+@APM-CDs has a good linear response to AA concentrations in the range of 0-500 μM (R2 = 0.99), with a detection limit of 80 nM. The fluorescence probe demonstrates good selectivity and sensitivity toward AA and has the potential for significant application in AA detection by simplifying procedures and reducing interference from impurities. © 2024, The Authors. All rights reserved.

关键词： Probes

Depth from Defocus Technique for High Number Densities and Non-Spherical Particles

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SSRN 2024年

作者： Xu, Rixin Huang, Zuojie Gong, Wenchao Zhou, Wu Tropea, Cameron School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering Shanghai China Institute for Fluid Mechanics and Aerodynamics Technical University of Darmstadt Darmstadt Germany

The Depth from Defocus (DFD) imaging technique for measuring the size and number concentration of particles in a dispersed two-phase flow has up to now been restricted to relatively sparse particle densities and to identifying only spherical particles. The present study examines two advancements to the technique, widening its range of application significantly. The first advancement introduces an image processing procedure which can identify and size particle images which are overlapping. This increases the tolerable number concentration of particles which can be identified and processed within the measurement volume. The second advancement explores the possibility of determining the size and position of non-spherical particles within an observation volume. These enhancements are experimentally validated using a dedicated apparatus in which particles of known size, shape and degree of overlapping images can be systematically varied. This experimental setup provides benchmark data to quantify the accuracy and limitations of the processing algorithms. © 2024, The Authors. All rights reserved.

关键词： Two phase flow

Investigation of Macro-fin Structure on Heat Transfer Performance of Close-Loop R410A Flashing Spray Cooling 15

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Investigation of Macro-fin Structure on Heat Transfer Perfor...

15th Triennial International Conference on Liquid Atomization and Spray Systems, ICLASS 2021

作者： Zhou, Zhifu Ji, Renjie Chen, Bin Thrassos, Panidis State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Laboratory of Applied Thermodynamics Mechanical Engineering Aeronautics Department University of Patras Rio Patras26504 Greece

The rapid development in performance, integration and miniaturization of electronics and other high power devices cause huge heat flux values. However, transitional cooling methods can hardly meet the requirement of dissipating effectively the high heat flux at the normal working temperature (usually smaller than 75 oC). The refrigerants flash evaporation spray cooling with phase change has been considered as one of the most promising technologies of heat dissipation for electronic devices and other high power devices due to its high heat removal capability at relatively low surface temperature, cooling uniformity, non-corrosivity. This study presents an experimental study on the heat transfer performance of the close-loop R410A flashing spray cooling, mainly focusing on the influence of macro-fin structure of cooling surface. The flat, square fin, pyramid fin surfaces and a newly designed tetrahedral fin surface are systematically examined. The results indicate that the newly designed tetrahedral fin surface has superior cooling performance than other fin surfaces. © 2021 ICLASS 2021 - 15th Triennial International Conference on Liquid Atomization and Spray Systems. All Rights Reserved.

关键词： Electronic cooling

Regulating Surface Terminals and Interlayer Structure of Ti3c2tx for Superior Nh3 Sensing

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SSRN 2024年

作者： Li, Jiazheng Li, Yanqiong Zeng, Wen Bai, Bofeng Ren, Shan College of Materials Science and Engineering Chongqing University Chongqing400030 China School of Electronic information & Electrical Engineering Chongqing University of Arts and Sciences Chongqing400030 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China

MXene materials have exhibited potential in electrochemistry, particularly in gas sensing, due to their excellent conductivity, large specific surface area of layered materials, and unique functional groups. However, the gas sensing performance of intrinsic 2D MXene materials is often limited by their fluorine-containing terminals and interfacial structure. In this study, based on intrinsic Ti3C2Tx, we employed alkali treatment and annealing to prepare oxygen-rich Ti3C2(OH)x/Ti3C2Ox with expanded interlayer spacing, achieving enhanced gas sensing performance for NH3. By utilizing the intercalation effect of layered materials and the synergistic effect of regulating MXene unique surface terminations, the sensing materials prepared have achieved optimization of surface chemistry and structural. Compared to intrinsic Ti3C2Tx, the interlayer spacing of oxygen-rich Ti3C2(OH)x/Ti3C2Ox increased from 9.1 Å to 12.1 Å. The surface terminations of oxygen-rich Ti3C2(OH)x/Ti3C2Ox have been defluorinated and oxygenated. The maximum response value of oxygen-rich Ti3C2(OH)x/Ti3C2Ox to NH3 was 35.66, approximately twice that of the original Ti3C2Tx at an NH3 concentration of 200 ppm. DFT (Density functional theory) calculations and DRIFT (In situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy) tests explained the interaction between the surface terminals and NH3, indicating good selectivity and sensitivity of oxygen-rich Ti3C2(OH)x/Ti3C2Ox to NH3. The results of this study demonstrate that the synergistic effects of surface chemistry and structural engineering are crucial for MXene to optimize the electrochemical performance, particularly the gas sensing performance. This provides a feasible approach for the performance optimization of intrinsic MXene materials. © 2024, The Authors. All rights reserved.

关键词： Oxygen

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

Enhancing Heat Transfer in Immersion Cooling Via Guest Non-Condensable Gas Microbubbles

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SSRN 2024年

作者： Luo, Peng Tong, Wei Wei, Lichuan Zhao, Yugang Zhang, Hua Cheng, Ping Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shenzhen Envicool Technology Co. Ltd. Shenzhen518129 China MOE Key Laboratory of Power Machinery and Engineering School of Mechanical Engineering Shanghai Jiaotong University Shanghai200240 China

Electronic systems produce increasingly high density of heat along with their performance elevated to meet the booming needs from industrials and human activities, and therefore more effective cooling methods are always in demand. Liquid immersion, both single-phase and dual-phase, is one of the most popular cooling methods developed, due to its simplicity, energy efficiency and operational feasibility. However, the heat dissipation capacity of single-phase immersion cooling is relatively low, while multi-phase only occurs above the boiling point of refrigerants. We here introduce a brand-new immersion cooling method with the injection of cold guest non-condensable gas (NCG) microbubbles. Experimental results show that the heat transfer rate is drastically enhanced, and in particular surface superheating is suppressed or even eliminated which is the key to maintaining the safety performance of micro-electronic chips. As bubbles approach the heating surface, they disturb the thermal boundary layer on the surface when their size is comparable with the layer thickness, attach to the surface serving as evaporation/boiling nuclei, and collide with existing bubbles to facilitate their departure. Also, the effects of bubble size distribution and pool subcooling are evaluated. The present cooling method performs better at a larger degree of pool subcooling while the effect of bubble size is relatively minor. This work demonstrates that guest NCG bubbles can drastically promote heat transfer in immersion cooling unlike others reported in the literature. The fundamental understanding of bubble dynamics upon impinging with the heating surface in subcooled liquid has promising applications in thermal management systems, such as electronic chips, nuclear reactors, heat exchangers, steam generators, and among others. © 2024, The Authors. All rights reserved.

关键词： Steam generators