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Study of Saturated Pool Boiling Heat Transfer Characteristics of R1.33zd(E) on Aluminum-Based Micro-Pin Finned Surfaces

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SSRN 2024年

作者： Yang, Xiaoping Bu, Shichao Jiang, Zhuye Chen, Hongqiang Sun, Zhen Zhang, Yonghai Wei, Jinjia School of Chemical Engineering and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Mobile Network and Mobile Multimedia Technology ZTE Corporation hillsides China

With the continuous development of chip integration and information technology, the heat dissipation has become a major limitation on the performance of electronic devices such as 5G base station, data center and so on, and meanwhile a challenge of conventional single-phase convection cooling methods. Boiling is prospective in high heat flux cooling and energy saving due to the usage of latent heat. R1.33zd(E), an environmentally friendly refrigerant (GWP=1. ODP=0) with a freezing point of -1.7°C, is a potential working fluid in phase-change heat sinks for geographical applications. Nevertheless, the poor boiling performance of R1.33zd(E) on plain surface due to the limitation in thermophysical properties must be enhanced. Moreover, conventional heat sinks are mostly copper-based, which are inconvenient for transportation and installation, and costly for production as well. In this work, micro pin fins in the range of 1.0-500 μm are fabricated on the aluminum surface to enhance the pool boiling of R1.33zd(E). Moreover, the influence of their size and saturation pressure on the bubble behavior, critical heat flux (CHF) and heat transfer coefficient (HTC) is experimentally and theoretically investigated. The results show that the increase of pressure, as well as the ensuing various nucleation site and capillary effect to rewet the evaporation region, can lead to an increase in the CHF and HTC. Notably, the 1.0-200 μm micro pin-finned surfaces reaches the highest CHF and 1.0 μm one owns the highest HTC, which is 21.% and 383% higher than that of plain surface, respectively. BY considering the balance of capillary effect and bubble convolution effect, a model of CHF is proposed to reveal the mechanism of optimum size of the micro pin fins. The predicted CHFs have an inaccuracy of less than ±20% comparing to experimental values. This paper makes up for the lack of basic experimental data on pool boiling of R1.33zd(E) on aluminum surface, which thus provides guidance for

关键词： Heat flux

Experiments and predictions for severe slugging of gas-liquid two-phase flows in a long-distance pipeline-riser system

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Ocean engineering 2024年 301卷

作者： Chang, Yingjie Xu, Qiang Zou, Suifeng Zhao, Xiangyuan Wu, Quanhong Wang, Yechun Thévenin, Dominique Guo, Liejin Shaanxi Key Laboratory of New Transportation Energy and Automotive Energy Saving Chang'an University Xi'an710064 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Laboratory of Fluid Dynamics and Technical Flows Otto-von-Guericke-Universität Magdeburg Magdeburg39106 Germany

Experiments concerning the flow regimes observed in gas-liquid two-phase flows in a long-distance pipeline-riser system were carried out and analyzed in this paper. The test loop with 0.075 m inner diameter consisted of a 31. m horizontal pipeline, followed by a 25 m downward-inclined pipe, and finally a 21.5 m riser pipe. An industrial-scale global flow regime map including 5 flow regimes was derived from differential pressure measurements in the riser and was used as a reference for improvements. Electrical capacitance volume tomography installed in the horizontal section was used to reconstruct the phase interface and calculate the average gas void fraction (GVF). An appropriate model for this system was selected by comparing the experimental GVF with different, widely used models. The occurrence of severe slugging flow (SS) can be predicted accurately using an improved model involving additional corrections that consider pipeline length, accurate GVF calculation, and gas density. This study supports the development of a suitable SS prediction model enabling safe design, operation, and control of practical systems. © 2024 Elsevier Ltd

关键词： Pipelines

Preparation, improvement, and application of metal–organic framework-based sensing materials for gas leakage and emission: A review

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Nano Materials Science 2025年

作者： Liu, Manyi Wang, Liang Ren, Shan Bai, Bofeng Chai, Shouning He, Chi Zheng, Chunli Yin, Xitao Li, Fengguang College of Materials Science and Engineering Chongqing University Chongqing400044 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China School of Physics and Optoelectronic Engineering Ludong University Yantai264000 China School of Materials Science and Engineering Hubei University of Automotive Technology Shiyan442002 China

Industrial gas leaks and flue gas emissions pose significant threats to the safety of industrial operations and the atmospheric ecological environment. Traditional gas sensing materials often struggle to meet the challenges posed by complex industrial environments. Recently, metal-organic framework (MOF)-based gas sensing materials have garnered significant attention in industrial gas detection due to their high sensitivity, selectivity, and tunable properties. The exponential increase in related publications highlights the growing research interest in this field. This paper presents a comprehensive review of the advantages of various types of metal-organic frameworks and their derivatives for detecting industrial gas leaks and flue gas emissions, alongside an introduction of representative MOF synthesis methods. Furthermore, the primary sensing mechanisms of MOF-based gas sensing materials and strategies for enhancing the sensing performance are summarized. The current state of MOF-based gas sensing materials in industrial gas detection is also discussed. Finally, the potential limitations, existing challenges, and future directions of MOF-based industrial gas sensing materials are systematically analyzed, with suggestions for addressing these challenges to advance industrial gas detection technologies. © 2025 Chongqing University

关键词： Application Improvement Industrial gas detection MOF-Based sensing materials Preparation

Numerical and Experimental Investigation of Proton Exchange Membrane Fuel Cell with Perpendicular Gas Supply Through the Ridge

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SSRN 2023年

作者： Zhang, Yan Lu, Xinyu Su, Jinzhan School of International Trade and Economics China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering School of Energy & Power Engineering Xi’an Jiaotong University Xi’an710049 China

The structural design of the cathode flow field in proton exchange membrane fuel cell (PEMFC) is essential for efficient gas supply and effective water removal. For investigating the mechanism behind the effect of gas flow direction on improving the performance of PEMFC, a novel modified serpentine flow channel with vertical inlets through the ridge for PEMFC was proposed and investigated by numerical and experimental methods. Under the operating voltage of 0.4 V, the vertical air supply mode exhibits a 7% higher current density compared to the parallel air supply mode. Compared with conventional air supply mode through the serpentine flow channel, vertical air supply mode modified serpentine through a tunnel inside the ridge exhibited higher oxygen uniformity and higher current density. Furthermore, we conducted research on the impact of physical parameters, including the porosity and thickness of the GDL, as well as the vertical gas supply pore density, on the performance of the PEMFC within the vertical gas supply mode. At an operating voltage of 0.4 V, the current density of PEMFC with a GDL thickness of 0.28 mm is 1.0009 A/cm2, which is 3.02% and 6.1.% higher than that of PEMFC with vertical inlets with GDL thickness of 0.38 and 0.48 mm, respectively. With a porosity of 0.6, the current density of PEMFC reaches 1.0395 A/cm2, surpassing that of PEMFCs with porosities of 0.2 and 0.4 by approximately 24.8% and 6.6%, respectively. Moreover, higher vertical inlet densities lead to improved PEMFC performance. Simulation and experimental results demonstrate that this modified flow field effectively addresses uneven current density distribution and enhances power output at low voltage. © 2023, The Authors. All rights reserved.

关键词： Porosity

From Lab to Industry: Scaling-Up Fe-Ni Bimetallic Nano Oxygen Carrier for Mid-Temperature Methane Chemical Looping Reforming

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SSRN 2024年

作者： Tang, Sanli Gai, Zhongrui Li, Yang Liu, Yunlian Liu, Mingkai Pan, Ying Jin, Hongguang Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China University of Chinese Academy of Sciences Beijing100049 China

Chemical looping methane reforming has emerged as a promising avenue to produce blue hydrogen. Currently, the satisfactory CH4 conversion and H2 productivity are usually seen under temperatures above 800 °C. Such temperature requirement poses challenges for industrial reactor design and product gas separation. Investigated widely in chemical looping, bimetallic oxygen carrier has both catalytic and oxygen releasing functions, thus expected to realize both lower reaction temperature and high performance. In this study, we present a nanoscale Fe-Ni bimetallic oxygen carrier for mid-temperature chemical looping methane reforming which can be implemented at large scale. By virtue of a synergy from nanoscale Fe-Ni dispersion, all oxygen carriers from lab-scale to 1.-kg scale can operate at 500-600 °C. The lab-scale oxygen carrier was found to convert >90% CH4, produce 3.5 H2 per CH4 molecule with 80-82% overall H2 purity at 575-600 °C. Following the proposed large-scale synthesis workflow, we acquired the 1.-kg scale oxygen carrier powder with 70% with 2.8 H2 from per CH4 molecule. The 1.-kg powders and beads both persisted phase, morphology and redox stability over 1.0 cycles. Further explorations revealed the similarity in structure and reaction performance between the lab-scale and 1.-kg scale powders, and differences in reaction dynamics between the 1.-kg powder and beads. These findings contribute to the mid-temperature chemical looping methane reforming by bridging {1. practices and industrial application. © 2024, The Authors. All rights reserved.

关键词： Powders

金属原子诱导的微环境调控在聚合氮化碳光催化析氢中的研究

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Science China Materials 2024年第6期67卷 1765-1779页

作者：赵大明杨雨骁 Vasileios Binas 沈少华 School of Advanced Energy Shenzhen Campus of Sun Yat-sen UniversityShenzhen 518107China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China Institute of Electronic Structure and Laser(IESL) Vasilika VoutonHeraklion GR-71110Greece Physical Chemistry Laboratory Chemistry DepartmentAristotle University of ThessalonikiThessaloniki 54124Greece

开发高效稳定的半导体光催化剂对光催化技术迈向实际应用至关重要.聚合物氮化碳(CN)因其优异的物理化学性质而被视为最具发展前景的制氢光催化剂之一.在过去几十年中,从热力学或动力学角度开发的一系列改性策略已经显著提升了CN的光催... 详细信息

开发高效稳定的半导体光催化剂对光催化技术迈向实际应用至关重要.聚合物氮化碳(CN)因其优异的物理化学性质而被视为最具发展前景的制氢光催化剂之一.在过去几十年中,从热力学或动力学角度开发的一系列改性策略已经显著提升了CN的光催化制氢性能.近期,金属原子修饰策略为CN改性提供了一条新途径,这种策略可以精确调控CN的微环境.本文全面回顾了金属原子修饰的CN光催化剂在光催化分解水制氢领域的最新研究进展,包括金属单原子修饰的CN、金属双原子修饰的CN、金属单原子与团簇共修饰的CN,重点阐述了金属原子对提升光催化性能的关键作用.此外,本文还全面总结了发展先进的金属原子修饰的CN光催化剂所面临的挑战与机遇.

关键词： metal atom polymeric carbon nitride hydrogen evolution photocatalysis solar energy conversion

Data Mining-Assisted Multi-Objective Optimization of Blade Angle Distributions for Efficiency and Stability Enhancement of a Free-Form Centrifugal Impeller

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SSRN 2024年

作者： Chen, Zhikai Chen, Ziying Sun, Jieshuai Guo, Yi Spence, Stephen Peng, Xueyuan Feng, Jianmei School of Energy and Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Mechanical Manufacturing and Biomedical Engineering Trinity College Dublin Dublin 2 Ireland State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China

The design optimization process for a centrifugal compressors faces significant trade-offs between efficiency, pressure ratio, and stable operating range. To address this challenge, a data mining assisted-optimization combining machine learning modelling method and non-dominated sorting genetic algorithm III (NSGA-III) has been proposed to enhance efficiency and pressure ratio while considering expansion of operational stability. A validated CFD numerical model was established for data generation. A Light-GBM model with Bayesian hyperparameter tuning and a deep feedforward neural network (DNN) model were constructed, and the better one was selected for performance prediction. Data mining techniques, including Sobol sensitivity analysis and SHAP, were employed to identify the key sensitive parameters and their interactions. Finally, a NSGA-III-based multi-objective optimization was conducted to determine the optimal geometry of the free-form surface impeller. Results showed that the blade angle distributions at the leading edge of mid-span and shroud profile were the most sensitive parameters affecting isentropic efficiency at the design point, with their recommended ranges identified. The optimized impeller has an increase in total pressure ratio of 2.98% and isentropic efficiency of 0.67% at the design point, especially exhibiting excellent aerodynamic performance at higher mass {1. rate conditions. The maximum improvements of total pressure ratio and isentropic efficiency were 1..91. and 9.53%, respectively, corresponding to the near choke mass {1. rate at the design speed. Additionally, operating stability was expanded with a 1.22% increase in total pressure ratio at near surge mass {1. rate at the design speed, which contributed to a delay in the onset of surge. © 2024, The Authors. All rights reserved.

关键词： Sensitivity analysis

An Operation Optimization of Cooling System for Reactor Shutdown in Pebble Bed Gas-Cooled Reactor

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SSRN 2024年

作者： Liu, Junfeng Wang, Chenglong Qiu, Suizheng Wang, Boyuan Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology Shaanxi Engineering Research Center of Advanced Nuclear Energy Xi’an Jiaotong University Xi’an710049 China Xi’an Thermal Power Research Institute Co. Ltd Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering China

For the emergency shutdown of a high temperature gas-cooled reactor pebble-bed module (HTR-PM) in its operation conditions, in the current design method with a low-flow auxiliary steam cooling technical solution, there are some security and economic issues, i.e. high thermal shock, long cooling time, and temperature drop rate exceeding the limit. To solve these problems, an optimized design method for the shutdown cooling system is presented. Through a simulation model of the shutdown cooling system based on Matlab/Simulink, the dynamic characteristics of the shutdown cooling system in its operation conditions are obtained, involving shutdown, low flow cooling, and water supply start-up stages. The results showed that with the optimized design method, the safety of the core and steam generator can both be ensured during the cooling process, and the cooling rate is significantly improved. Therefore, the optimized design method is feasible and advanced. © 2024, The Authors. All rights reserved.

关键词： Cooling

Effects of Inherent Aaems on Catalytic Gasification of Biomass with Large Particle Size Under Oxygen-Steam Atmosphere

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SSRN 2023年

作者： Ren, Jiyun Li, Yuhang Li, Yang Huang, Xiaole Jin, Xiaoling Yang, Chenglong Zhao, Hanchen 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 Xi’an Thermal Power Research Institue Co. Ltd. Xi’an710032 China

Oxygen-steam gasification of biomass is a promising technology because of its ability to improve syngas quality and reduce energy consumption. In this study, a fixed-bed reactor is employed to assess the effects of inherent alkali and alkaline earth metals (AAEMs) on the catalytic gasification of candlenut wood with large particle size under oxygen-stream atmosphere. The results show that the acid-washing would remarkably remove the inherent AAEMs in biomass, which is affected by the grain direction. In terms of the gasified chars derived from acid-washed biomass, AAEMs content gradually decreases along the end surface and radial direction, which could also be observed from the 3D reconstruction of X-ray CT images. A large number of mesopores (20-30 μm) align along the grain direction in the biomass sample. Numerous micropores (1.-20 μm), mesopores (20-30 μm), and macropores (30-50 μm) are present in the gasified char derived from the biomass sample. Micropores (1.-20 μm) prevail in the gasified char from the acid-washed biomass sample. Inherent AAEMs facilitate an augmentation in char yield as well as BET and total pore volume of gasified char. AAEMs and grain direction have a slight effect on functional groups of gasified char. The tar component is remarkably affected by the grain direction. Acid-washing pretreatment augments the content and organic species of M2-M4 compounds (containing 2-4 benzene rings) in the tar. It also leads to a decrement in concentrations of H2, CH4, and CO2 by 1..49% and 1..35%, 0.51. and 0.89%, 2.32% and 1.37% in syngas for two-grain direction, respectively. But it raises the CO concentration by 1..1. and 1..1.%, resulting in a reduction of 4.09% and 1.53% in syngas calorific value. A decrement in the volume fraction of CnHx induced from AAEMs is significantly affected by the grain direction. © 2023, The Authors. All rights reserved.

关键词： Biomass