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Numerical study on oxy-fuel co-combustion of semi-coke and coal in utility boiler: Insight into NOx emission and combustion efficiency 7

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Numerical study on oxy-fuel co-combustion of semi-coke and c...

7th International Conference on power engineering, ICOPE 2019

作者： Feng, Qinqin Wang, Chang'an Lv, Qiang Zhao, Lin Du, Yongbo Wang, Pengqian Zhang, Jingwen Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China

Oxy-fuel combustion is clean and efficient combustion technology, which not only benefits the large-scale capture of CO2 but also reduces NOx emission, and then promotes the efficient and clean utilization of carbon-based solid fuels. This study mainly aimed at the oxy-fuel co-combustion of semi-coke and coal in utility boiler with special insight into NOx emission and combustion efficiency. The simulation results showed that when the blending ratio of semi-coke was 45%, the NOx concentration at the furnace outlet under oxy-fuel condition was increased with the oxygen content. The flue gas circulation modes ("dry" versus "wet") had insignificant impact on the NOx emission when the initial oxygen concentration was set as 24% and 27%. When the blending ratio of semi-coke was 70%, the differences of NOx emission between "dry" and "wet" flue gas circulation modes were enlarged with rise in oxygen content under oxy-fuel condition. For oxy-fuel cases, despite of the growth of burnout ratio, the carbon content in fly ash first increased and then decreased with the rise of oxygen content. With the oxygen concentration increased to 30%, lower carbon content in fly ash and higher burnout ratio could be observed in comparison to the cases under air condition. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Fly ash

Numerical Simulation for Non-Uniform Ptco Catalyst Degradation Under Constant Voltage Condition and its Impact on Pemfc Performance

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SSRN 2023年

作者： Yang, Yunjie Bai, Minli Zhou, Zhifu Wu, Wei-Tao Hu, Chengzhi Gao, Linsong Li, Yang Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116023 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China

PtCo alloys are commonly utilized as catalysts in proton exchange membrane fuel cell (PEMFC) to reduce Pt loading and to achieve higher oxygen reduction reaction (ORR) activity. However, long-time operation can result in a reduction in electrochemical surface area (ECSA) in PEMFC. Meanwhile, the dissolved Co2+ may also contribute to additional local oxygen transport resistance. In this study, catalyst aging model and Co2+ transport and its effect on oxygen transport model have been integrated with the 3D single phase PEMFC performance model to develop a long-term performance model for investigating the impact of non-uniform catalyst degradation and Co2+ contamination on PEMFC performance during constant voltage operation. The results show that Co2+ contamination causes additional mass transfer losses and reduces the peak power of PEMFC. And it is found that the non-uniform degradation of catalyst and Co2+ contamination eventually affects the current density distribution in aged PEMFCs. In addition, the model is also applied to study a 50 cm2 PEMFC under long time constant voltage operation. The predicted ECSA loss is 73.1% and 62.0%, and output power reduction is 55.9% and 43.0% after 80,000 hours at a constant voltage of 0.75 V and 0.65 V, respectively. © 2023, The Authors. All rights reserved.

关键词： Numerical models

A Comprehensive Review on Multi-Dimensional Heat Conduction of Multi-Layer and Composite Structures:Analytical Solutions

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Journal of Thermal Science 2021年第6期30卷 1875-1907页

作者： AMIRI DELOUEI Amin EMAMIAN Amin SAJJADI Hasan ATASHAFROOZ Meysam LI Yueming WANG Lian-Ping JING Dengwei XIE Gongnan Department of Mechanical Engineering University of BojnordBojnordIran Mechanical Engineering Department Shahrood University of TechnologyShahroodIran Department of Mechanical Engineering Siijan University of TechnologySiijanIran School of Aerospace Engineering Xi’an Jiaotong UniversityXi’an 710049China Guangdong Provincial Key Laboratory of Turbulence Research and Applications Center for Complex Flows and Soft Matter Research and Department of Mechanics and Aerospace EngineeringSouthern University of Science and TechnologyShenzhen 518055China Department of Mechanical Engineering University of DelawareNewarkDelaware19711USA International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China Department of Mechanical and Power Engineering Northwestern Polytechnical UniversityXi'an 710072China

Heat conduction in multi-layer and composite materials is one of the fundamental heat transfer problems in many industrial *** to different materials types,interface conditions,and various geometries of these laminates,the heat conduction mechanism is more complicated than that of one-layer isotropic *** solutions are the best ways to study and understand such problems in *** this study,different existing analytical solutions for heat conduction in multi-layer and composite materials are reviewed and classified in rectangular,cylindrical,spherical,and conical *** boundary conditions,internal heat source,and thermal contact resistance as the most critical parameters in the solution complexity investigated in the literature,are discussed and summarized in different *** types of multi-layer structures such as isotropic,anisotropic,orthotropic,and reinforced laminates are included in this *** is found that although more than half a century has passed since the beginning of the research on heat transfer in multi-layer composites,new researches that can help with a better understanding in this area are still being *** challenges and shortcomings in this area are also discussed to guide future researches.

关键词： multi-dimensional heat conduction composite laminates multi-layer structures analytical solutions interface contact resistance

Theoretical and experimental advances on heat transfer and flow characteristics of metal foams

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Science China(Technological Sciences) 2020年第5期63卷 705-718页

作者： WANG Hui GUO LieJin CHEN Kang School of Environmental Science and Engineering Donghua UniversityShanghai 201620China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China Institute of Solar Engineering Technology Northwest Engineering Corporation LimitedPowerChinaXi’an 710065China

Open cell metal foam can be applied to greatly improve thermal performance of heat sink and heat exchanger,so that it has been widely used in the fields of thermal(or heat)control system of aerospace vehicle and energy utilization system and become a very important topic for research in the aerospace thermophysics field,and more and more attentions have been *** optimal design of metal foam heat transfer devices is based on the understanding the flow and heat transfer characteristics in metal *** article reviews some recent progresses of theoretical and experimental researches on heat transfer enhancement and flow characteristics of metal *** found that the pore cell simplification models of metal foams generally fall into four categories,among which the most commonly used cell model is Kelivin *** exploratory works performed by the current authors are also introduced,such as the effect of boundary conditions on the heat transfer enhancement;the theoretical modelling of interfacial convective heat transfer taking into account heat conduction between foam ligaments;and the flow characteristics under relatively high *** analytical results show that the flow characteristics of metal foam at relatively high speed are completely different from those at low speed,a further thorough study of the heat transfer and flow characteristics of metal foam is necessarily *** this paper,two types of partial filling techniques are *** heat transfer performance of partially filled tubes was evaluated by both the performance evaluation criteria and the performance evaluation plot of enhanced heat transfer techniques oriented for *** results show that the filling type of metal foam have a significant impact on its heat transfer enhancement ***,the filling method of metal foam should be further studied,in order to optimize the thermophysical properties of heat transfer devices.

关键词： metal foam effective thermal conductivity interfacial convective heat transfer coefficient heat transfer enhancement thermal radiation

Study on the Flame Structure and flow Field of Hydrogen-Enriched Combustion in Array Micro-Tube

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SSRN 2024年

作者： Tian, Liang Feng, Wenbin Han, Xiao Liu, Yuzhi Liu, Hongfang Cai, Xiao School of Energy and Environmental Engineering Hebei University of Technology Tianjin300401 China National Key Laboratory of Science and Technology on Aero-Engine Aero thermodynamics Research Institute of Aero-Engine Collaborative Innovation Center for Advanced Aero-Engine Beihang University Beijing100191 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China

Addressing climate change and reducing greenhouse gas emissions are critical priorities. Utilizing hydrogen-rich methane or pure hydrogen as fuels within gas turbines, facilitated by array micro-tube premixed combustion technology, is anticipated to markedly accelerate the decarbonization process of the energy sector. In this study, the flame structure of the array micro-tube premixed burner under various fuel compositions was examined using OH-Planar Laser-Induced Fluorescence (OH-PLIF) and Particle Image Velocimetry (PIV) measurement techniques. The effects of the equivalence ratio (φ) and the hydrogen power ratio (HPR) on the characteristics of the flame front, including its curvature, density, volume, and the associated flow field properties, were discussed. As φ and HPR increase, the wrinkled structure of the flame front is significantly enhanced, with a more pronounced effect on smaller scales. This enhancement leads to the separation of the unburned pockets from the main flame. Concurrently, both the flame length and flame area decrease with the augmentation of φ and HPR, indicating a more concentrated combustion process and increased combustion intensity under hydrogen-enriched and pure hydrogen conditions. The study also observed a slight increase in both the negative and positive curvatures of the flame front, with a more notable increase in negative curvature. The increased negative curvature results in an elevated degree of wrinkling and a higher value of Σ (flame surface density), reaching a maximum of 0.876 mm-1 under the conditions where φ is 0.8 and (mean progress variable) is 0.5, resulting in the smallest observed flame volume of 100.6 mm3. Upon coupling the flame with the flow field, it was discovered that the exit flow field of the array micro-tube exhibits symmetry and a characteristic conical flame shape. The burning velocity of the side flame brushes increases, and the velocity peak shifts upstream. The above findings confirms that the additio

关键词： flow fields

Numerical Simulations on Hybrid Thermal Management of Mini-Channel Cold Plate and Pcm for Lithium-Ion Batteries

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SSRN 2024年

作者： Liu, Yang Zhou, Zhifu Wu, Wei-Tao Wei, Lei Li, Yang Liu, Xinyu Huang, Heng Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China

In this study, a novel battery thermal management system (BTMS), combining phase change material (PCM) and mini-channel cold plates (MCPs), was modeled and analyzed. First, the effects on single cell cooling using MCPs and PCM alone are investigated at different coolant rates, temperatures, and PCM thicknesses. Then, the hybrid thermal management system (HTMS) is developed with the aim of reducing the cooling load of the PCM through hybridization with MCPs and the optimal combination of them is investigated. At the end of this work, the thermal performance of a battery pack with a hybrid thermal management structure has been analyzed, where the cold plate can take away the heat from the PCM to restore its thermal storage capacity. The results show that the combination of 3 channel and 10 mm PCM with 0.1 m/s coolant velocity and 20°C coolant temperature is the quit suitable regarding the cooling performance. Under 2C discharging rate, this design reduces the maximum battery temperature to 40°C, which is 32.5% lower, and the average temperature to 35℃, which is 41% lower than it without cooling. The study's findings offer potential new strategies and predictions for hybrid thermal management that utilize MCPs and PCM. © 2024, The Authors. All rights reserved.

关键词： Lithium-ion batteries

Numerical Simulations for Comparison of Cold Plate Cooling and Hfe-7000 Immersion Cooling in Lithium-Ion Battery Thermal Management

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SSRN 2024年

作者： Liu, Xinyu Zhou, Zhifu Wu, Wei-Tao Wei, Lei Hu, Chengzhi Li, Yang Huang, Heng Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China

In this work, fluorinated liquids can be used as a new immersion coolant for effective battery thermal management (BTM) because of their insulating and non-flammable inert characteristics. In this research, the liquid chosen for immersion cooling is HFE-7000, characterized by a boiling point of 34°C. The analysis of bubble kinetics is employed to investigate the heat transfer mechanism in two-phase immersion cooling by examining the behavior of bubbles during the boiling process. The square ternary Li-ion batteries are subjected under loads of 2C and 3C cooled by immersion cooling and a mini-channel cold plate as a comparison. It turns out that immersion liquid cooling modules offer superior thermal performance. Under constant current (CC), the peak temperature is reduced by 4.89°C and 9.31°C compared with the mini-channel cold plate cooling (CPC). Under dynamic load conditions, the maximum temperature rise of the battery is reduced by 29.89% and 43.89% compared to CPC. As a passive heat dissipation method, two-phase immersion cooling reduces the design requirements for active control. Also, it delivers an efficient battery thermal management system (BTMS) designed for upcoming electric vehicles (EVs). © 2024, The Authors. All rights reserved.

关键词： Lithium-ion batteries

Thermal Management for the 18650 Lithium-Ion Battery Pack by Immersion Cooling with Fluorinated Liquid

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SSRN 2023年

作者： Li, Yang Bai, Minli Zhou, Zhifu Wu, Wei-Tao Hu, Chengzhi Gao, Linsong Liu, Xinyu Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116023 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China

In this work, a new battery thermal management system (BTMS) utilizing a SF33-based liquid immersion cooling (LIC) scheme has been proposed. Firstly, the comparative investigation focuses on the temperature response of the LIC and forced air cooling (FAC) modules in different scenarios. The results demonstrate that LIC module effectively mitigates heat accumulation, thereby presenting notable advantages in terms of temperature control and equalization, even though the LIC module works under the stage without phase change occurrence. During 2C and 3C charging, the highest temperatures of the LIC module are observed to be 10 °C and 19.1 °C only lower than those of the FAC module, respectively. Furthermore, the highest temperature differences of the LIC module are only 12.89% and 8.57% of the corresponding values exhibited by the FAC module. Moreover, the associated cooling energy consumption for the LIC module is greatly reduced, amounting to only 16.47% and 43.76% of that required by the FAC module. Subsequently, an active control scheme for the LIC is initially proposed, and the phase change process of the LIC under various discharging rates is recorded and analyzed using a high-speed camera. This study serves as a preliminary proof of concept for the feasibility of SF33-based LIC scheme in BTMS. © 2023, The Authors. All rights reserved.

关键词： Lithium-ion batteries

A review on thermal application of metal foam

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Science China(Technological Sciences) 2020年第12期63卷 2469-2490页

作者： CHEN Kang GUO LieJin WANG Hui State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China Institute of Solar Engineering Technology Northwest Engineering Corporation LimitedPowerChinaXi’an 710065China School of Environmental Science and Engineering Donghua UniversityShanghai 201620China

Heat exchangers embedded with metal foam are drawing increasing attention in the thermal application field,due to the performance of low density,large ratio of surface area to volume as well as high thermal conductivity. In these applications,compact heat exchanger,solar thermal facilities and thermal energy storage are the three core components. This paper focuses on the lasted advances in thermal applications,presenting a review of theoretical and experimental progress over metal foam in thermal application. The empirical and theoretical models for pressure drop,heat transfer coefficient and performance evaluation criteria of compact heat exchangers with metal foam are reviewed and discussed,especially different optimized *** is a trade-off between heat transfer enhancement and increase of pressure drop. Some exploratory work performed by present authors are also introduced. The manufacturing,heat transfer and flow characteristics of tube bundle wrapped with metal foam are taken into account for optimization of heat exchanger. It is confirmed that the conversion mechanism of heat transfer is carried out that heat conduction is the dominative term at high dimension permeability. The correlations of heat transfer rate and pressure drop for staggered and single row tube bundle wrapped with metal foam are concluded,respectively. The effects of different bonding methods are revealed for point-contact in metal foam and base tube. The powder-sintering method can provide a stable and minimum-thickness bonding layer. Various types of solar thermal facilities utilized metal foam to improve the energy conversion efficiency from solar radiant energy to thermal energy are also reviewed and discussed,including solar collector for intermediate-low temperature utilization and solar receiver for high temperature utilization. The Last but not least,existing and future metal foam thermal application stations are overviewed.

关键词： metal foam heat transfer enhancement solar thermal facilities thermal energy storage