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学者姓名:刘中良
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Abstract :
Non-equilibrium phase transition flow is prevalent and of great irreversible loss during the transonic mixing process of steam ejector, but its complex evolution law is thus far unclear. In this study, a considerate two-phase ejector model was developed to investigate the non-equilibrium phase transition flow characteristics by means of CFD numerical simulation, including how, where and to what extent the phase transition occurs. Additionally, the quantitative analysis of the operating parameters influences on the phase transition flow and ejector's entrainment performance were conducted. Results showed that the evolution law of condensate is highly consistent with the pressure fluctuation of shock wave. Non-equilibrium condensation is to be intensified as the primary fluid pressure increases, and the entrainment performance thus worsens. For raising the secondary fluid pressure, the case is opposite, the entrainment ratio w increases by 17.8 %. Superheating the working fluids can restrain the droplet development, and more small-sized droplets therefore emerge, but w only raises by a maximum of 3.53 %. However, it is hard to restrain the condensate generation in primary jet flow by superheating the secondary fluid, both suction pressure and w decrease. This study provides meaningful guidance for reducing the irreversibility loss from non-equilibrium phase transition flow.
Keyword :
Performance improvement Performance improvement Operating parameters analysis Operating parameters analysis Non-equilibrium phase transition flow Non-equilibrium phase transition flow Steam ejector Steam ejector difference difference Shock wave Shock wave
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GB/T 7714 | Tang, Yongzhi , Zhong, Zilong , Liu, Zhongliang et al. Study on evolution law of non-equilibrium phase transition flow and performance improvement of steam ejector for MED-TVC desalination system [J]. | ENERGY , 2025 , 316 . |
MLA | Tang, Yongzhi et al. "Study on evolution law of non-equilibrium phase transition flow and performance improvement of steam ejector for MED-TVC desalination system" . | ENERGY 316 (2025) . |
APA | Tang, Yongzhi , Zhong, Zilong , Liu, Zhongliang , Lu, Lin , Huang, Yichen , Wen, Chuang . Study on evolution law of non-equilibrium phase transition flow and performance improvement of steam ejector for MED-TVC desalination system . | ENERGY , 2025 , 316 . |
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Abstract :
针对平板热管均热器内部狭小空间存在着强烈的沸腾与凝结相互作用,以去离子水为工质,可视化实验研究了冷凝面上发生的凝结现象及其对相变腔传热性能的影响。通过分析冷凝面上液滴的形成、长大、汇聚成液膜、滴落,以及气液界面产生气泡随气流运动对冷凝液膜的冲刷作用,揭示了不同热流密度和充液率时相变腔冷凝面传热传质特性对沸腾-凝结共存相变传热影响的内在机理。实验结果表明:受重力影响,水蒸气在冷凝面上凝结有液滴和液膜共存并相互转化的特性,冷凝面热阻在相变腔总热阻中占比65%~88%,适宜的充液率有利于沸腾气泡冲刷冷凝壁面,加快冷凝液的回流,改善冷凝面及相变腔的传热性能;随着热流密度的增大,沸腾过程变得剧烈,冷凝面受沸腾气泡的冲刷频率提高,冷凝液回流速度加快,冷凝面热阻减小,传热性能得到提高。
Keyword :
凝结与沸腾共存 凝结与沸腾共存 冷凝液回流 冷凝液回流 气泡冲刷 气泡冲刷 充液率 充液率 可视化 可视化 相变腔 相变腔
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GB/T 7714 | 李艳霞 , 史壮壮 , 刘中良 . 相变腔冷凝现象对沸腾-凝结共存相变传热的影响 [J]. | 北京工业大学学报 , 2024 , (01) : 113-122 . |
MLA | 李艳霞 et al. "相变腔冷凝现象对沸腾-凝结共存相变传热的影响" . | 北京工业大学学报 01 (2024) : 113-122 . |
APA | 李艳霞 , 史壮壮 , 刘中良 . 相变腔冷凝现象对沸腾-凝结共存相变传热的影响 . | 北京工业大学学报 , 2024 , (01) , 113-122 . |
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Abstract :
The effects of cold surface temperature, wet air state (temperature and humidity) and original drop size on frost dendrites growth of two neighboring separate frozen water drops of same size under natural convection conditions were investigated by quantitative measurement. It was determined that for different cold plate surface temperature conditions, i.e., the ordinary-low temperature and the cryogenic temperature range, the frost formation mechanism is different. Under the conditions that the air temperature is not too high and absolute humidity is not too excessive, the influence of frozen water drop size on the longest dendrite of frost crystals becomes more and more obvious with the decrease in cold plate temperature. The changes in air temperature and relative humidity both change air absolute humidity, so they have similar effects on the growth of dendrites. However, the effect of wet air state on the growth of frost dendrites is not monotonous, which needs to be considered comprehensively in combination with heat and mass transfer and the existence of heavy phase layer. The thickness of 'the initial continuous frost layer' was measured and it was disclosed that the initial frost layer thickness is 1.7-3.0 times that of the height of the frozen water drop diameter. This value may be possibly used as initial frost layer thickness in heat and mass transfer-based frost layer growth prediction models, at least for ordinary-low temperature conditions.
Keyword :
initial frost layer thickness initial frost layer thickness dendrite growth dendrite growth frost crystal frost crystal cryogenic cold surface cryogenic cold surface
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GB/T 7714 | Yu, Fengjiao , Liu, Zhongliang , Li, Yanxia et al. Experimental Study of Frost Crystals Dendrite Growth on Two Neighboring Separate Frozen Water Drops on a Cryogenic Cold Surface under Natural Convection Conditions [J]. | ENERGIES , 2023 , 16 (4) . |
MLA | Yu, Fengjiao et al. "Experimental Study of Frost Crystals Dendrite Growth on Two Neighboring Separate Frozen Water Drops on a Cryogenic Cold Surface under Natural Convection Conditions" . | ENERGIES 16 . 4 (2023) . |
APA | Yu, Fengjiao , Liu, Zhongliang , Li, Yanxia , Chen, Yanling , Li, Yi . Experimental Study of Frost Crystals Dendrite Growth on Two Neighboring Separate Frozen Water Drops on a Cryogenic Cold Surface under Natural Convection Conditions . | ENERGIES , 2023 , 16 (4) . |
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Quantitative measurements were carried out of the dendrite frost crystal growth under natural convection conditions on a frozen water drop sitting on a cold surface whose temperature is as low as-190 degrees C to study the effects of cold surface temperature, wet air state and original water drop size. In order to classify the influences of different cold surface temperature regions, the frost crystal dendrite growth of both ordinary-low and cryogenic cold surface temperatures were investigated. It was found that the cold plate surface temperature has a direct influence on frost formation mechanism. Decreasing the cold surface temperature for ordinary-low cold surface temperatures will enhance and for cryogenic cold surface temperatures will suppress the frost crystal dendritic growth of the frozen water drop. The measurements disclosed that the length of the longest frost crystal dendrite grows almost linearly with time, esp. in the early stage. The effects of the water drop sizes on the longest frost crystal dendrite growth become more and more obvious as the cold surface temperature decreases. The influence of air relative humidity on the frost crystal dendrite growth is something similar to that of air temperature under given conditions, since their change both changes the absolute air humidity. A very peculiar phenomenon, i.e. the influence of wet air state on frost crystal dendrite growth is not monotonous, was observed. These findings are important for understanding and studying the frost formation and growth, especially the initial frost formation period, on low temperature surfaces.
Keyword :
Cryogenic cold surface Cryogenic cold surface Natural convection Natural convection Dendrite growth Dendrite growth Frost crystal Frost crystal
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GB/T 7714 | Yu, Fengjiao , Liu, Zhongliang , Li, Yanxia et al. Experimental study of frost crystal dendrite growth on a cryogenic cold surface under natural convection conditions [J]. | INTERNATIONAL JOURNAL OF REFRIGERATION , 2022 , 144 : 305-315 . |
MLA | Yu, Fengjiao et al. "Experimental study of frost crystal dendrite growth on a cryogenic cold surface under natural convection conditions" . | INTERNATIONAL JOURNAL OF REFRIGERATION 144 (2022) : 305-315 . |
APA | Yu, Fengjiao , Liu, Zhongliang , Li, Yanxia , Chen, Yanling , Li, Yi . Experimental study of frost crystal dendrite growth on a cryogenic cold surface under natural convection conditions . | INTERNATIONAL JOURNAL OF REFRIGERATION , 2022 , 144 , 305-315 . |
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Abstract :
Cost-effective and easy-to-operate optimization strategies are always crucial for accelerating the practical application of microbial fuel cells (MFCs). In this study, sodium citrate, a widely-used food and industrial additive with the properties of pH adjustment and microbial degradability, is applied as anolyte additive in MFCs to enhance the bioelectricity generation. The maximum power density and coulombic efficiency of MFC with 0.2 g L−1 sodium citrate addition (0.2-Cit MFC) is achieved as 784.05 mW m−2 and 56.17% respectively, increasing by 58.33% and 64.38% compared with that of the MFC without sodium citrate addition (0-Cit MFC). Electrochemical impedance spectroscopy, cyclic voltammetry and pH tests performed in each MFC cycle show that adding sodium citrate significantly improves the biocatalytic activity of anode, slows down the performance decline tendency and restrains the sharply-dropped pH as the operation cycle increases. Besides, microbial community analysis reveals that the electroactive biofilm in 0.2-Cit MFC has the obviously higher population abundance and diversity than that in 0-Cit MFC. This finding is important in that sodium citrate as the bi-functional and bio-degradable additive can help stimulate the activity of bioanode and regulate the pH in biofilm region simultaneously without causing secondary pollution. © 2020 Elsevier B.V.
Keyword :
Fuel additives Fuel additives Sodium compounds Sodium compounds Sodium metallography Sodium metallography Food additives Food additives Electrophysiology Electrophysiology Cyclic voltammetry Cyclic voltammetry Microbial fuel cells Microbial fuel cells Microorganisms Microorganisms Electrochemical impedance spectroscopy Electrochemical impedance spectroscopy Cost effectiveness Cost effectiveness Efficiency Efficiency Biofilms Biofilms
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GB/T 7714 | Chen, Wenwen , Liu, Zhongliang , Li, Yanxia et al. Improved electricity generation, coulombic efficiency and microbial community structure of microbial fuel cells using sodium citrate as an effective additive [J]. | Journal of Power Sources , 2021 , 482 . |
MLA | Chen, Wenwen et al. "Improved electricity generation, coulombic efficiency and microbial community structure of microbial fuel cells using sodium citrate as an effective additive" . | Journal of Power Sources 482 (2021) . |
APA | Chen, Wenwen , Liu, Zhongliang , Li, Yanxia , Xing, Xiaoye , Liao, Qiang , Zhu, Xun . Improved electricity generation, coulombic efficiency and microbial community structure of microbial fuel cells using sodium citrate as an effective additive . | Journal of Power Sources , 2021 , 482 . |
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Abstract :
There is pressing need to explore the fundamental link between the mixing efficiency and the entrainment performance for ensuring an efficient working of ejector in the associated energy systems. This study details where, how and to what extent the primary and entrained flows mix inside the steam ejector through a novel ejector model with species transport. The evolution laws of the mixing layer growth, the entrainment performance and the mass transfer of two streams are systematically discussed under various operational conditions. Further, their fundament links are clearly presented in a form of functional relation. The key findings emerged from this study: The mixing begins over a fluctuating mixing layer since the mixing chamber entrance. In the situation of critical operational models, the mixing layer experiences a fluctuating and exponential growth successively, but its development is severely obstructed under the subcritical models. Additionally, the entrainment ratio and the non-mixing length ratio are highly linear correlation with the mass transfer ratio. The variations of operational parameters essentially change the relative mass transfer capacity of the entrained flow. The more easily the entrained flow mixes into the primary jet flow, a faster mixing layer growth and higher entrainment performance are to be gained. © 2020 Elsevier Ltd
Keyword :
Mass transfer Mass transfer Ejectors (pumps) Ejectors (pumps) Mixing Mixing
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GB/T 7714 | Tang, Yongzhi , Liu, Zhongliang , Li, Yanxia et al. Study on fundamental link between mixing efficiency and entrainment performance of a steam ejector [J]. | Energy , 2021 , 215 . |
MLA | Tang, Yongzhi et al. "Study on fundamental link between mixing efficiency and entrainment performance of a steam ejector" . | Energy 215 (2021) . |
APA | Tang, Yongzhi , Liu, Zhongliang , Li, Yanxia , Huang, Zhifeng , Chua, Kian Jon . Study on fundamental link between mixing efficiency and entrainment performance of a steam ejector . | Energy , 2021 , 215 . |
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Abstract :
There is not a specific technical proposal to be able to achieve a clear presentation of the complex mixing process between the primary and entrained flows within the steam ejector. In this study, a novel ejector model with species transport is proposed that can clearly elucidate how, when, where and to what extent the two streams mix. Systematic quantitative analysis toward the mixing of two streams is performed from the perspectives of mass, momentum and energy transfer. Further, the similarities and differences of the mixing process among three analytical perspectives are clarified. Key results revealed that the mixing mainly occurs at the nearby of the local mixing layer, and there are still some distances from the homogenous mixing state after the mixing chamber process, only up to 80.6% the mixing uniformity phi obtains. Additionally, the mixing layer follows a similar growth trajectory, and phi increases as mixing continues regardless of an analytical perspective. However, a much faster mixing is observed from the mass transfer perspective. Specifically, phi(M) (80.6%) is significantly larger than phi(V) (60.7%) and phi(E) (59.6%) at the mixing chamber outlet. It can be concluded that the essential mass mixing laws of the two streams are not necessarily achieving a complete replication whether from the perspective of momentum or energy transfer. These key findings provide a more in-depth and comprehensive understanding of the mixing process inside the ejector.
Keyword :
Mass, momentum and energy transfers Mass, momentum and energy transfers Steam ejector Steam ejector Multi-perspective comparisons Multi-perspective comparisons Mixing process Mixing process Species transport Species transport
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GB/T 7714 | Tang, Yongzhi , Liu, Zhongliang , Li, Yanxia et al. Mixing process of two streams within a steam ejector from the perspectives of mass, momentum and energy transfer [J]. | APPLIED THERMAL ENGINEERING , 2021 , 185 . |
MLA | Tang, Yongzhi et al. "Mixing process of two streams within a steam ejector from the perspectives of mass, momentum and energy transfer" . | APPLIED THERMAL ENGINEERING 185 (2021) . |
APA | Tang, Yongzhi , Liu, Zhongliang , Li, Yanxia , Zhao, Fei , Fan, Pengyan , Chua, Kian Jon . Mixing process of two streams within a steam ejector from the perspectives of mass, momentum and energy transfer . | APPLIED THERMAL ENGINEERING , 2021 , 185 . |
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Microbial fuel cells (MFCs) are a promising biotechnology that realizes the transformation of wastewater treatment from an energy consumption to an electricity generation process. However, the tedious process and the large resources consuming in preparing powder ORR catalysts are still non-negligible limiting factors for application. This study aims at proposing an energy-efficient method for preparing three-dimensional binder-free air cathode for MFCs: non-noble composite catalysts based on graphene and MnO2 are synthesized directly on stainless steel fiber felt (SSFF) by pre-fixing and electro-reducing graphene oxide on SSFF (rGO-SSFF), and then in-situ depositing MnO2 nanocatalysts on rGO-SSFF (rGO@MnO2-SSFF). The experimental results show that the ORR ability of rGO@MnO2-SSFF cathode is greater than that of Pt/C-CC cathode, even if the performance of rGO@MnO2 powder catalyst is slightly lower than that of the traditional Pt/C catalyst. The excellent performance is found to be due to the three-dimensional framework-pore structure of SSFF which helps the prepared cathode possess larger electrochemical active area (8415.18 m(2) m(-3)) than Pt/C-CC cathode (7518.13 m(2) m(-3)). The proposed method provides a new way to reduce the cost (labor, materials and energy) of air cathode while ensuring the high electricity output of MFCs. (C) 2021 Elsevier Ltd. All rights reserved.
Keyword :
Stainless steel fiber felt Stainless steel fiber felt Air cathode Air cathode Microbial fuel cells Microbial fuel cells Oxygen reduction activity Oxygen reduction activity Preparation optimization Preparation optimization
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GB/T 7714 | Chen, Wenwen , Liu, Zhongliang , Li, Yanxia et al. High electricity generation achieved by depositing rGO@MnO2 composite catalysts on three-dimensional stainless steel fiber felt for preparing the energy-efficient air cathode in microbial fuel cells [J]. | ENERGY , 2021 , 222 . |
MLA | Chen, Wenwen et al. "High electricity generation achieved by depositing rGO@MnO2 composite catalysts on three-dimensional stainless steel fiber felt for preparing the energy-efficient air cathode in microbial fuel cells" . | ENERGY 222 (2021) . |
APA | Chen, Wenwen , Liu, Zhongliang , Li, Yanxia , Liao, Qiang , Zhu, Xun . High electricity generation achieved by depositing rGO@MnO2 composite catalysts on three-dimensional stainless steel fiber felt for preparing the energy-efficient air cathode in microbial fuel cells . | ENERGY , 2021 , 222 . |
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Flow and heat transfer characteristics of oil-based drilling cuttings in a screw-driving spiral heat exchanger were numerically simulated. The influence of spiral tube rotation speed, Reynolds number of oil-based drilling cuttings, cross-sectional shape on flow and heat transfer characteristics were studied. The results show that with rotation speed increases, the heat transfer coefficient and outlet temperature of oil-based drilling cuttings all increase. In addition, when Reynolds number is less than 250, Nusselt number increases rapidly with the increase of Reynolds number, and Reynolds number has little influence on Nusselt number when it is more than 250. Besides, Nusselt number increases with the increase of curvature ratio di=D. In order to facilitate engineering design, a correlation for heat transfer of oil-based drilling cuttings flowing in the shell side of the heat exchanger is obtained. © 2021, Science Press. All right reserved.
Keyword :
Infill drilling Infill drilling Reynolds number Reynolds number Heat exchangers Heat exchangers Screws Screws Nusselt number Nusselt number
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GB/T 7714 | Zhao, Fei , Li, Yan-Xia , Liu, Zhong-Liang et al. Flow and Heat Transfer Characteristics of Oil-based Drilling Cuttings in Screw-driving Spiral Heat Exchanger [J]. | Journal of Engineering Thermophysics , 2021 , 42 (4) : 959-965 . |
MLA | Zhao, Fei et al. "Flow and Heat Transfer Characteristics of Oil-based Drilling Cuttings in Screw-driving Spiral Heat Exchanger" . | Journal of Engineering Thermophysics 42 . 4 (2021) : 959-965 . |
APA | Zhao, Fei , Li, Yan-Xia , Liu, Zhong-Liang , Mi, Fu-Lin , Gao, Li-Qing , Li, Qing-Fang et al. Flow and Heat Transfer Characteristics of Oil-based Drilling Cuttings in Screw-driving Spiral Heat Exchanger . | Journal of Engineering Thermophysics , 2021 , 42 (4) , 959-965 . |
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Abstract :
为快速掌握区域内全部水泥企业的碳排放情况,在部分企业实际生产数据未知时,也能建立其生产碳排放清单,文中基于熟料生产特征,构建了可根据设备设计产能和运行时长两种参数来核算企业CO_2排放的数值模型。以京津冀地区59条典型水泥熟料生产线的生产数据作为统计样本,借助Eviews对生产线的实际产能、熟料烧成煤耗与设计产能间的关系进行回归分析,并引入了生产时间修正系数,完成了CO_2核算模型的建立。将其应用到京津冀地区全部106条水泥熟料生产线中,得出2018年度京津冀地区水泥熟料总产量,该核算值与数字水泥网发布的统计数据之间的相对误差均值为7.81%。通过核算,CO_2直接排放系数为0.93 t CO...
Keyword :
实际产能 实际产能 水泥熟料烧成煤耗 水泥熟料烧成煤耗 CO_2排放量核算 CO_2排放量核算 生产时长 生产时长 水泥熟料生产企业 水泥熟料生产企业 CO_2排放清单 CO_2排放清单
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GB/T 7714 | 杨楠 , 李艳霞 , 赵盟 et al. 水泥熟料生产企业CO_2直接排放核算模型的建立 [J]. | 气候变化研究进展 , 2021 , 17 (01) : 79-87 . |
MLA | 杨楠 et al. "水泥熟料生产企业CO_2直接排放核算模型的建立" . | 气候变化研究进展 17 . 01 (2021) : 79-87 . |
APA | 杨楠 , 李艳霞 , 赵盟 , 吕晨 , 刘中良 , 陈莎 . 水泥熟料生产企业CO_2直接排放核算模型的建立 . | 气候变化研究进展 , 2021 , 17 (01) , 79-87 . |
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