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学者姓名:侯予
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Abstract :
High-speed centrifugal pumps with low specific speed have the characteristics of a small flowrate, a high head, and being compact and light weight, making them promising candidates for applications in the thermal management of aerospace and electronic devices. The energy loss in the low specific speed pump is critical and complex due to the large impeller diameter, the narrow and long flow channel, and the small outlet width. In this paper, an analysis method based on an energy loss model and computational fluid dynamics simulations (ELM/CFD) is proposed to analyze the performance of the low specific speed pump with a fully sealed structure. Experiments were carried out under variable water flowrates. The results show that the empirical correlation method failed to accurately predict the performance of high-speed centrifugal pumps, because the bearing clearance leakage and motor channel leakage are ignored. Moreover, the volume loss and hydraulic loss are calculated based on the empirical parameters of commonly used pumps that are different from the high-speed pump with the low specific speed in the complex flow channel structure. The ELM/CFD method calculates various loss power based on the simulation results and can predict the head and efficiency with deviations less than 2% and 5%, respectively. ELM/CFD can accurately analyze the optimization direction of the pump. The hydraulic loss and the volume loss of the impeller are the dominant factors that restrict the pump efficiency under the lower flowrates, while the hydraulic loss of subsequent flow channels becomes important under the larger flowrates.
Keyword :
centrifugal pump CFD simulation energy loss model low specific speed
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GB/T 7714 | Xue, Rong , Lin, Xinyi , Zhang, Beile et al. CFD and Energy Loss Model Analysis of High-Speed Centrifugal Pump with Low Specific Speed [J]. | APPLIED SCIENCES-BASEL , 2022 , 12 (15) . |
MLA | Xue, Rong et al. "CFD and Energy Loss Model Analysis of High-Speed Centrifugal Pump with Low Specific Speed" . | APPLIED SCIENCES-BASEL 12 . 15 (2022) . |
APA | Xue, Rong , Lin, Xinyi , Zhang, Beile , Zhou, Hong , Lai, Tianwei , Hou, Yu . CFD and Energy Loss Model Analysis of High-Speed Centrifugal Pump with Low Specific Speed . | APPLIED SCIENCES-BASEL , 2022 , 12 (15) . |
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As a requirement for sustainable development, air-cycle refrigeration has received wide attention as a candidate for environmentally friendly air conditioning technology. In this study, the thermodynamic performance of air refrigeration cycles is investigated in compartment air conditioning. The effects of compressor efficiency, expander efficiency, ambient humidity, all-fresh-air supply and ambient pressure on the cycle performance are presented. The effects of compressor arrangement in the high-pressure cycle and the low-pressure cycle are compared. An open-loop high-pressure cycle has a larger COP than that of an open-loop low-pressure cycle but requires larger heat exchange. The performance of air refrigeration cycles with full fresh air is studied, and the influence of fresh air is discussed. Schemes for condensed water recirculation with wet compression are proposed, which can improve the COPs of open-loop low-pressure cycles by 44.7%, 48.8% and 48.4%. In the air conditioning of plateau trains, open-loop high-pressure cycles have slightly lower COPs, but they can supply air with elevated pressure and oxygen concentration.
Keyword :
air cycle COP fresh air conditioner reverse Brayton refrigerator
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GB/T 7714 | Yang, Xiaoling , Wang, Zhefeng , Zhang, Ze et al. Thermodynamic Analysis of Air-Cycle Refrigeration Systems with Expansion Work Recovery for Compartment Air Conditioning [J]. | APPLIED SCIENCES-BASEL , 2022 , 12 (10) . |
MLA | Yang, Xiaoling et al. "Thermodynamic Analysis of Air-Cycle Refrigeration Systems with Expansion Work Recovery for Compartment Air Conditioning" . | APPLIED SCIENCES-BASEL 12 . 10 (2022) . |
APA | Yang, Xiaoling , Wang, Zhefeng , Zhang, Ze , Chen, Shuangtao , Hou, Yu , Chen, Liang . Thermodynamic Analysis of Air-Cycle Refrigeration Systems with Expansion Work Recovery for Compartment Air Conditioning . | APPLIED SCIENCES-BASEL , 2022 , 12 (10) . |
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Abstract :
The liquefaction of hydrogen is considered to be a crucial process in the large-scale utilization of hydrogen energy. In hydrogen liquefaction, hydrogen turbo-expander is a key refrigerating machine for high liquefaction efficiency. Performance of the turbo-expander is directly affected by the hydrogen gas bearings. To obtain a deep understanding of the performance characteristics of hydrogen gas bearings, the static and dynamic characteristics of herringbone grooved journal bearings under hydrogen and other lubricating gases were numerically calculated and compared. The bearing load capacity and critical mass of hydrogen gas bearings were slightly lower than those of helium-, air- and nitrogen-lubricated bearings. To improve the performance of the hydrogen gas bearings used in high-speed turbo-machinery, the influence of working conditions was analyzed. It is found that the load capacity of hydrogen gas bearings can be improved by increasing the ambient pressure, reducing the gas film clearance, and raising the bearing eccentricity ratio. Meanwhile, the critical mass increases, and the bearing dynamic stability is enhanced.
Keyword :
bearing performance herringbone grooved journal bearing hydrogen energy hydrogen lubrication
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GB/T 7714 | Qiang, Mingchen , Zhao, Qi , Yan, Shaohang et al. Performance Prediction of High-Speed Hydrogen Gas-Lubricated Herringbone Grooved Journal Bearing [J]. | APPLIED SCIENCES-BASEL , 2022 , 12 (13) . |
MLA | Qiang, Mingchen et al. "Performance Prediction of High-Speed Hydrogen Gas-Lubricated Herringbone Grooved Journal Bearing" . | APPLIED SCIENCES-BASEL 12 . 13 (2022) . |
APA | Qiang, Mingchen , Zhao, Qi , Yan, Shaohang , Liu, Xue , Hou, Yu , Lai, Tianwei . Performance Prediction of High-Speed Hydrogen Gas-Lubricated Herringbone Grooved Journal Bearing . | APPLIED SCIENCES-BASEL , 2022 , 12 (13) . |
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Abstract :
Frost usually grows on the cooling surface of heat transfer equipment, which often operates under different working pressures. In such conditions, one of the fundamental influencing factors of frosting, the diffusion coefficient of water vapor around the cooling surface, is different from that in the normal atmosphere pressure. In order to investigate the pressure effect on frosting, a test rig for frosting visualization is designed. The role of working pressure around the cooling surface on the frost crystal morphologies and frost layer characteristics is evaluated under different air parameters and temperatures of cooling surface. The vertical growth and lateral distribution of frost crystals are strongly related to working pressure around the cooling surface. More frost crystal morphologies and faster growth rate of frost layer are presented at a lower pressure. The frost thickness, frost accumulation and density reduce with higher pressure. The dimensionless correlation of frost thickness is proposed considering working pressure around the cooling surface, humid air parameters, and temperature of cooling surface.
Keyword :
correlation frost crystal morphology frosting frost layer characteristic pressure
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GB/T 7714 | Lai, Tianwei , Liu, Xue , Dong, Xiaojun et al. Experimental Study on Frost Crystal Morphologies and Frosting Characteristics under Different Working Pressures [J]. | APPLIED SCIENCES-BASEL , 2022 , 12 (8) . |
MLA | Lai, Tianwei et al. "Experimental Study on Frost Crystal Morphologies and Frosting Characteristics under Different Working Pressures" . | APPLIED SCIENCES-BASEL 12 . 8 (2022) . |
APA | Lai, Tianwei , Liu, Xue , Dong, Xiaojun , Qiang, Mingchen , Yan, Shaohang , Hou, Yu . Experimental Study on Frost Crystal Morphologies and Frosting Characteristics under Different Working Pressures . | APPLIED SCIENCES-BASEL , 2022 , 12 (8) . |
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Abstract :
The multi-nozzle spray cooling with liquid nitrogen can achieve high heat transfer rate and uniform temperature for a large-scale environmental simulation system. The understanding of the flow characteristics is crucial to the accurate control of the mass flow rates and the temperature distribution in a cryogenic system. This article combines the experimental and numerical approach to reveal the external and internal flow characteristics of the multi-nozzle spray with liquid nitrogen. It is found that a higher injection pressure is followed by an increasing mass flow rate under a given nozzle combination. The number and position of the low-temperature region in the downstream field correspond to the number and the arrangement of spraying nozzles under each combination. The pressure differences have little effect on the spray cone angle of a single-nozzle. The flow swirl is induced by the slotted swirl in the nozzle chamber and the cavitation is caused by the abrupt change structure at the orifice. In the absence of the friction and the resistance, the ratio of the mass flow rate in the multi-nozzles to that in the single-nozzle is basically equal to the ratio of the nozzle numbers. And the nearly equal amount of liquid nitrogen flows into each single nozzle of a multi-nozzle array under the varied injection pressure and inlet temperature conditions. The experimental research and the theoretical analysis are to provide insights on the practical engineering application of the multi-nozzle spray cooling in a cryogenic environmental simulation system. © 2021
Keyword :
Cooling Liquefied gases Liquid nitrogen Mass transfer Spray nozzles Spray steelmaking Temperature
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GB/T 7714 | Xue, Rong , Ruan, Yixiao , Liu, Xiufang et al. Internal and external flow characteristics of multi-nozzle spray with liquid nitrogen [J]. | Cryogenics , 2021 , 114 . |
MLA | Xue, Rong et al. "Internal and external flow characteristics of multi-nozzle spray with liquid nitrogen" . | Cryogenics 114 (2021) . |
APA | Xue, Rong , Ruan, Yixiao , Liu, Xiufang , Zhong, Xin , Chen, Liang , Hou, Yu . Internal and external flow characteristics of multi-nozzle spray with liquid nitrogen . | Cryogenics , 2021 , 114 . |
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Abstract :
Cavitation is likely to occur in micron clearance, which affects the efficiency and reliability of the fluid machinery. Due to the confinement effect and high-speed shearing, evolution process of cavitation bubbles takes on new characteristics in the confined clearance. In this paper, a visualized experimental apparatus was developed based on the structural characteristics of micron clearance. The cavitation characteristics and bubble dynamics of R134a in divergent and convergent flow path are captured in the high-speed visualization experiment. For the single cavitation bubble, the growth, deformation and fragmentation processes are investigated under different subcooling degrees and clearance heights. The shape and growth process of single-bubble is captured during experiment. The fitting curves are obtained based on the flow and the single-bubble morphology in the micron clearance. The occurrence probability of single-bubble and bubble cluster varies with subcooling degree, clearance height and pressure difference.
Keyword :
Bubble dynamics Cavitation Confinement effect High speed shearing Micron clearance
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GB/T 7714 | Lai, Tianwei , Yan, Shaohang , Wang, Yanwu et al. Experimental study on vaporous cavitation of R134a in micron clearance [J]. | EXPERIMENTAL THERMAL AND FLUID SCIENCE , 2021 , 129 . |
MLA | Lai, Tianwei et al. "Experimental study on vaporous cavitation of R134a in micron clearance" . | EXPERIMENTAL THERMAL AND FLUID SCIENCE 129 (2021) . |
APA | Lai, Tianwei , Yan, Shaohang , Wang, Yanwu , Liu, Xue , Yang, Shenyin , Ding, Pei et al. Experimental study on vaporous cavitation of R134a in micron clearance . | EXPERIMENTAL THERMAL AND FLUID SCIENCE , 2021 , 129 . |
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Abstract :
Gas foil bearing has been widely used in high-speed turbo machinery due to its oil-free, wide temperature range, low cost, high adaptability, high stability and environmental friendliness. In this paper, state-of-the-art investigations of gas foil bearings are reviewed, mainly on the development of the high-speed turbo machinery in China. After decades of development, progress has been achieved in the field of gas foil bearing in China. Small-scale applications of gas foil bearing have been realized in a variety of high-speed turbo machinery. The prospects and markets of high-speed turbo machinery are very broad. Various high-speed turbomachines with gas foil bearings have been developed. Due to the different application occasions, higher reliability requirements are imposed on the foil bearing technology. Therefore, its design principle, theory, and manufacturing technology should be adaptive to new application occasions before mass production. Thus, there are still a number of inherent challenges that must be addressed, for example, thermal management, rotor-dynamic stability and wear-resistant coatings.
Keyword :
foil bearing gas bearing industrial application turbo machinery
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GB/T 7714 | Hou, Yu , Zhao, Qi , Guo, Yu et al. Application of Gas Foil Bearings in China [J]. | APPLIED SCIENCES-BASEL , 2021 , 11 (13) . |
MLA | Hou, Yu et al. "Application of Gas Foil Bearings in China" . | APPLIED SCIENCES-BASEL 11 . 13 (2021) . |
APA | Hou, Yu , Zhao, Qi , Guo, Yu , Ren, Xionghao , Lai, Tianwei , Chen, Shuangtao . Application of Gas Foil Bearings in China . | APPLIED SCIENCES-BASEL , 2021 , 11 (13) . |
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Abstract :
Protective structure, acted as a substructure of internal insulation system in cryogenic wind tunnel, is in possession of such advantages of isolating insulation unit from cryogenic medium and reducing cold energy loss. However, the protective structure is continuously subjected to alternating pressure during the operation of cryogenic wind tunnel. Thus, the type selection and strength check on connecting fastener, acted as weak bearing component in protective structure, are investigated. Firstly, according to the composition of protective structure, three key connecting positions are determined and the corresponding connecting fasteners are selected. Then, according to the cryogenic wind tunnel working condition, the theoretical mechanical models of connecting fasteners are built under different working conditions. Finally, involving the force and moment balance, mechanics analysis and strength check are conducted on connecting fasteners. The obtained results show that the selected fasteners are conformed to the strength requirement of cryogenic wind tunnel in service, which paves the way for building the cryogenic wind tunnel in the future. © 2020 Published under licence by IOP Publishing Ltd.
Keyword :
Artificial intelligence Cryogenics Energy dissipation Fasteners Internet of things Wind tunnels
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GB/T 7714 | Yuan-Jia, Song , Huan, Lai , Wan-Hua, Chen et al. Selection and strength check on fasteners of protective structure in cryogenic wind tunnel [C] . 2020 . |
MLA | Yuan-Jia, Song et al. "Selection and strength check on fasteners of protective structure in cryogenic wind tunnel" . (2020) . |
APA | Yuan-Jia, Song , Huan, Lai , Wan-Hua, Chen , Wei, Zhang , Yu, Hou . Selection and strength check on fasteners of protective structure in cryogenic wind tunnel . (2020) . |
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Abstract :
Cryo-compressed hydrogen storage has potential applications in fuel-cell vehicles due to its large storing density and thermal endurance. The dormancy of storage can be extended when considering the endothermic conversion of para-to-ortho hydrogen. In present study, a thermodynamic model is established to analyze the effect of the conversion in a cryogenic pressure vessel. The influence of the parameters such as the filling density, initial temperature and initial ortho hydrogen fraction is studied. It is demonstrated that different 'transition pressures' for the vessels exist for different filling densities. The conversion can carry out sufficiently and the dormancy can be extended significantly when the designed release pressure of the vessel matches with the transition pressure. The heat of absorption increases with the initial o-H2 fraction, whereas the peak of conversion rate occurs earlier for the vessel with a large initial o-H2 fraction. The dormancy can be extended by 163% for the vessel with filling density of 70 kg/m3. The investigations on the effect of the para-to-ortho hydrogen conversion can provide useful guideline for the design of cryo-compressed hydrogen vessels. © 2020 Hydrogen Energy Publications LLC
Keyword :
Filling Fuel cells Hydrogen storage Thermoanalysis Thermodynamic properties
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GB/T 7714 | Chen, Liang , Xiao, Runfeng , Cheng, Cheng et al. Thermodynamic analysis of the para-to-ortho hydrogen conversion in cryo-compressed hydrogen vessels for automotive applications [J]. | International Journal of Hydrogen Energy , 2020 , 45 (46) : 24928-24937 . |
MLA | Chen, Liang et al. "Thermodynamic analysis of the para-to-ortho hydrogen conversion in cryo-compressed hydrogen vessels for automotive applications" . | International Journal of Hydrogen Energy 45 . 46 (2020) : 24928-24937 . |
APA | Chen, Liang , Xiao, Runfeng , Cheng, Cheng , Tian, Gui , Chen, Shuangtao , Hou, Yu . Thermodynamic analysis of the para-to-ortho hydrogen conversion in cryo-compressed hydrogen vessels for automotive applications . | International Journal of Hydrogen Energy , 2020 , 45 (46) , 24928-24937 . |
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Abstract :
Cryogenic two-phase turbo-expander becomes a prevalent option in process design of high efficiency cryogenic liquefaction system, especially in modern air separation system and helium system. Computational code of turbine off-design performance prediction in overheated expansion and non-equilibrium condensation module are well established in our former works, and the mechanism of nucleation and droplet growth in spontaneous condensation is revealed. However, the analysis between single and two-phase expansion as well as wetness influence on turbine performance is not conducted yet. In this study, we investigate a turbo-expander performance analysis in a wide temperature range (Tin = 118 K ~ 98 K), and present the wetness loss assessment and quantitative calculation in two-phase expansion process. By referring to the previous off-design performance of overheated expansion, the two-phase expansion performance under different pressure ratio and rotational speed is obtained and compared. According to the continuous inlet temperature drop process, the expansion is categorized into three types and their zone boundaries are divided. The transitional feature of unexpected change is frequently figured out on the expansion zone boundary, and the reaction ratio and pressure ratio in diffuser during the continuous inlet temperature drop process are analyzed detailed, which shows the unique and significant role of wetness effect in two-phase expansion. Based on the experimental wetness loss assessment method established by Baumann in wet steam turbine, two numerical assessments by using overheated expansion and equilibrium condensation model as reference expansion are analyzed. To quantitatively analyze the wetness loss influence, the efficiency drop caused by wetness and the relative wetness loss are calculated by eliminating other component losses in turbine, and the relative wetness loss is fitted with outlet liquid mass fraction mathematically to assist future design of cryogenic two-phase turbo-expanders. © 2020 Elsevier Ltd
Keyword :
Condensation Cryogenics Drops Efficiency Numerical methods Steam condensers Turboexpanders
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GB/T 7714 | Niu, Lu , Zhong, Zhigang , Hong, Xingfu et al. Numerical study on two-phase expansion performance and quantitative analysis of wetness loss in cryogenic turbo-expander [J]. | Cryogenics , 2020 , 110 . |
MLA | Niu, Lu et al. "Numerical study on two-phase expansion performance and quantitative analysis of wetness loss in cryogenic turbo-expander" . | Cryogenics 110 (2020) . |
APA | Niu, Lu , Zhong, Zhigang , Hong, Xingfu , Chen, Shuangtao , Hou, Yu . Numerical study on two-phase expansion performance and quantitative analysis of wetness loss in cryogenic turbo-expander . | Cryogenics , 2020 , 110 . |
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