检索结果-内蒙古大学图书馆

A Study of Optimal Refrigerant Charge Amount Determination for Air-Conditioning heat Pump System in Electric Vehicles

引用

ENERGIES 2020年第3期13卷 657-657页

作者： Li, Kang Yu, Jun Liu, Mingkang Xu, Dan Su, Lin Fang, Yidong Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Key Lab Multiphase Flow & Heat Transfer Shanghai Shanghai 200093 Peoples R China

With regard to concerns about an electric vehicle's driving range extension in a cold climate, an air-conditioning heat pump (ACHP) shows considerable advantage over thermoelectric heaters for battery energy conservation. The effect of refrigerant charge amount for cooling and heating performance of the ACHP system is significant. The optimal charge, realizing the optimal system performance, is usually determined by experiments of cooling and heating performance. In this paper, the optimal charge determination process based on a newly designed ACHP applied in electric vehicles was introduced. Relationships of characteristics with charge in two modes were investigated by experimental and theoretical methods. Firstly, the performance of the ACHP system was respectively investigated at different charge amounts in cooling and heating operating conditions according to key parameters of system cycles. Secondly, the intersection platforms of subcooling and superheat variation curves with refrigerant charge amount were obtained for determining optimal charge amount of the system further by comprehensive analysis. Finally, the theoretical calculation of charge with three instructive and classical void friction correlation models were applied for better comparisons. It was found that charge amount calculated by the Hughmark model proved to be most consistent with the comprehensive experimental results.

关键词： cooling and heating performance optimum refrigerant charge charge determination modelling void fraction correlation

来源：评论

学校读者我要写书评

暂无评论

Effects on the Various Aluminum Foam Fenders of a Tripod Offshore Wind Turbine Collision Due to a Ship

引用

MARINE TECHNOLOGY SOCIETY JOURNAL 2020年第1期54卷 79-96页

作者： Han, Zhiwei Zhao, Xinlei Li, Chun Ding, Qinwei Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 20093 Peoples R China Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai Peoples R China

The interest in offshore wind energy is growing all over the world. Increasingly, offshore wind turbines (OWTs) are being installed close to shipping lanes, which puts them at risk of potential collisions with ships during their service period. This article aims to investigate the structural dynamic response of OWTs to a ship collision. Considering the structure size of the fender as well as the nonlinear characteristics of the structural materials, a finite element model of a 5,000-ton ship colliding with a 4-MW tripod OWT has been developed using the explicit finite element code LS-DYNA. By observing the collision energy conversion, contact force, fender performance, Von Mises stress on the tripod, shear stress, and dynamic response of a nacelle in differently sized fender collision scenarios, it was observed that when the thickness of the fender surpasses 1.1 m, it can protect the OWT from a collision more effectively than with no fender case. Otherwise, the local contact force is cushioned by aluminum foam materials, whose contact force leads to a whole movement of the bearing tripod. The tripod with the aforementioned 1.1-m fender generates a contact force, Von Mises stress, and a shear stress, as well as the anticollision characteristics of a fender and the dynamic responses of a nacelle in 15 scenarios. Therefore, the structural design of the fender is essential in the safety of a tripod foundation in a collision. This article will provide a better understanding of the collision characteristics of the fender in the future.

关键词： offshore wind turbine structural dynamic response tripod aluminum foam fender

来源：评论

学校读者我要写书评

暂无评论

PLIF thermometry using OH origin from photo dissociation of water 6

PLIF thermometry using OH origin from photo dissociation of ...

引用

6th International Symposium on Laser Interaction with Matter

作者： Li, Guohua Ye, Jingfeng Zhang, Zhenrong Wang, Sheng Shao, Jun Hu, Zhiyun Wang, Jinhua Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China State Key Laboratory of Laser Interaction with Matter Northwest Institute of Nuclear Technology Xi’an China Shanghai Jiao Tong University Sichuan Research Institute Chengdu China

ISBN: (纸本)9781510660236

A technique that expands the OH-LIF thermometry range is developed. The PLIF of OH from dissociation of water in gas phase is used for temperature measurement both in flame and room air. The thermometry results from photo-fragmentation laser induced fluorescence(PF-PLIF) at time delay from 200ns to 1ms after dissociation agree well with results from PLIF of OH from burning which are calibrated by CARS thermometry. And the results in room air agree with environment temperature at time delay from 50ns to 0.2ms. These two results validate the PF-PLIF thermometry method both in flame and room temperature, which allowing thermometry at low temperature or non-reaction region. At last the PF-PLIF was applied in a jet flow, and the temperature results from PF-PLIF, PLIF and CARS at different height of jet were compared. © 2022 SPIE.

关键词： Dissociation

来源：评论

学校读者我要写书评

暂无评论

Effect of enhancement in metal foam pore density on heat transfer of phase-change materials

引用

INTERNATIONAL COMMUNICATIONS IN heat AND MASS transfer 2023年第1期144卷

作者： Wang, Zilong Sun, Xiangxin Zhu, Mengshuai Zhu, Liucan Zhang, Hua Dou, Binlin Wu, Weidong Szymczak, Piotr Wu, Rui Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Univ Warsaw Inst Theoret Phys Fac Phys Pasteura 5 PL-02093 Warsaw Poland Shanghai Jiao Tong Univ Dept Mech Engn Shanghai 200240 Peoples R China

To explore the effect of metal foam(MF)pore density on the melting and heat transfer of phase-change materials (PCMs), a semi-cylindrical visualization experimental setup was established to experimentally study copper MFs with different pore densities coupled with paraffin wax. The results showed that as pore density increases, the melting time of the composite PCMs decreases compared to that of pure paraffin wax by 11.5%, 16.2% and 18.1% for pore densities of 5, 20, and 30 PPI, respectively. Composite PCMs with a pore density of 30 PPI exhibited fastest melting and lowest maximum temperature difference during melting. Considering the relative thermal energy storage(TES) capacity and relative TES rate, composite PCMs with a pore density of 30 PPI exhibited optimal overall thermal storage performance. Furthermore, heat conduction was the primary means of thermal transmission during the melting of the bottom paraffin. However, the melting of the upper paraffin was nevertheless influenced by natural convection, Hence, as pore size decreased, the influence on the weakening of natural convection became more significant. The results of the study provide guidance for the optimal design of latent heat storage devices for semi-cylinders.

关键词： Copper foam Phase change materials Pore density Enhancement of heat transfer Thermal storage performance

来源：评论

学校读者我要写书评

暂无评论

Molecular dynamics simulations on dissociation of CO2 hydrate in the presence of inhibitor

引用

CHEMICAL PHYSICS 2020年 538卷 110894-110894页

作者： Liu, Ni Zhou, Jiali Hong, Chunfang Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

The dissociation kinetics of CO2 hydrate are investigated by molecular dynamics (MD) simulation in the presence of thermodynamic inhibitor glycine (5 wt%, 10 wt%, 15 wt%, 20 wt%) and kinetic inhibitor glucose (1.2 wt%, 2.0 wt%, 3.8 wt%). The molecular dynamics simulations are performed at 273.15 K and 3 MPa under the isothermal-isobaric (NPT) ensemble. The configuration, radial distribution functions, mean square displacement, and density are analyzed respectively. It is found that the dissociation rate of CO2 hydrate is increased in the presence of two inhibitors. The optimal concentration of glycine is 10 wt% and that is 1.2 wt% for glucose. The results indicate different mechanisms for two inhibitors. Glycine accumulates on the solid-liquid surface of the initial structure, and the clathrate hydrate structure is destroyed due to the aggregation of hydroxyl (-OH) and amidogen (-NH2) with water hydrogen bond in the hydrate structure. While glucose accelerates the dissociation of hydrates because of the synergistic effect of steric hindrance, owing to its ring-shaped structure and the disruption of functional groups.

关键词： CO2 hydrate Molecular dynamic simulation Dissociation Inhibitor

来源：评论

学校读者我要写书评

暂无评论

Pressure fluctuation of steam on the disc in a triple eccentric butterfly valve

引用

SN APPLIED SCIENCES 2020年第7期2卷 1193页

作者： Haimin, Wang Feng, Hu Xiangshuai, Kong Si, Chen Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

The triple eccentric butterfly valve has an excellent structure for sealing fluid and can also produce additional torque to assist in opening or closing the valve. However, flow separation and vortex shedding often occur because of the rugged surface of the valve disc. Pressure fluctuation on the disc induces vibration and can severely damage the valve and pipeline. To investigate the pressure fluctuations due to steam, the CFD method is used to simulate the 3D unsteady flow inside the valve and to obtain the transient pressure and velocity at key points in the five typical sections in the fully open state. The discrete Fourier transform method is adopted to analyze the spectrum parameters. The Strouhal numbers for vortex shedding are also obtained. Finally, an experimental modal analysis is conducted to test the natural frequency of the disc-stem assembly. The tested natural frequency is much higher than the highest steam pressure fluctuation frequency in the case of the maximum flow rate. Moreover, pressure fluctuations caused by fluid force do not induce resonance of the disc-stem assembly and there no lock-in phenomenon occurs.

关键词： Pressure fluctuation Triple eccentric butterfly valve Disc-stem assembly High-temperature steam

来源：评论

学校读者我要写书评

暂无评论

Numerical study on a novel flapping-foil energy harvester with 2D vortex generator

引用

OCEAN engineering 2022年第Part2期266卷

作者： Huang, Shengxian Wang, Jiayue Hou, Longfeng Wang, Ying Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Natl Key Lab Sci & Technol Aerodynam Design & Res Xian 710072 Peoples R China

This research presents a passive control energy capture device with two-dimensional (2D) vortex generator on the surface of flapping foil. When Reynolds number equals to 13800, based on the dynamic grid technique, the effects of the key parameters such as the position size as well as shape of 2D vortex generator on the efficiency of flapping foil are simulated, and the results are showed as following: (1) Compared with the original flapping foil, the passive control flapping foil with 2D vortex generator not only can effectively increase the energy exchange of boundary layer on the surface of flapping foil, but also can increase the force consistent with the direction of flapping foil movement and the pressure difference between the pressure surface and the suction surface, so as to improve the energy harvesting efficiency of the flapping foil. (2) The 2D vortex generator with triangle shape at 30% of chord length has an optimal size, which can improve the energy efficiency of the flapping foil energy harvesting device by 6.2% compared with the original (ORI) model. (3) The 2D vortex generator designed in this research does not generate new vortex, while only interfering with the vortex generated at the leading edge of the airfoil, so as to realize the function similar to the traditional vortex generator. The results of this research are of great significance to improve the design of flapping foil, and can provide some guidance for engineering practice.

关键词： 2D vortex generator Flapping foil Numerical simulation Energy acquisition

来源：评论

学校读者我要写书评

暂无评论

Suppressing condensation frosting using micropatterned ice walls

引用

APPLIED THERMAL engineering 2023年第1期224卷

作者： Zuo, Zichao Zhao, Yugang Li, Kang Zhang, Hua Yang, Chun Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China China Aerodynam Res & Dev Ctr Key Lab Icing & Anti Deicing Mianyang 621000 Sichuan Peoples R China Nanyang Technol Univ Sch Mech & Aerosp Engn Singapore 639798 Singapore

Condensation frosting is encountered ubiquitously in our daily life and numerous industrial applications, rooting many detrimental consequences in heat transfer and mechanical stabilities. In latest decades, both active de-frosting and passive anti-frosting methods have been developed. In this work, we adopt the concept of three-dimensional overlapping dry zones by patterning microscopic ice walls on a smooth substrate, engendering a sustainable frost coverage of less than 13 %. Patterned ice walls prevent vapor deposition on the substrate base by absorbing all incoming moisture on upper sidewalls, leaving the substrate base free of contaminates from both frost and condensate. To ensure vapor preferentially depositing on upper sidewalls, a critical ice wall height exists, below which fine ice grains initiate in the adjacent of the substrate base and grow substantially faster, compromising the anti-frosting performance. The proposed surface shows reasonable durability when exposed to varying substrate supercooling, and frost coverage may increase due to covering and fracturing of the out-of-plane growth of feather-like ice clusters at large substrate supercooling. Our findings provide an effective anti-frosting surface design that doesn't require any chemical or mechanical modifications on the targeted surfaces, showing great advantages compared to conventional icephobic surface designs.

关键词： Anti-frosting Microscopic patterns Dendrite growth Frost coverage

来源：评论

学校读者我要写书评

暂无评论

Enhancing biochar oxidation reaction with the mediator of Fe²⁺/Fe³⁺ or NO₂^-/NO₃^- for efficient hydrogen production through biochar-assisted water electrolysis

引用

ENERGY CONVERSION AND MANAGEMENT 2021年 244卷 114523-114523页

作者： Ying, Zhi Geng, Zhen Zheng, Xiaoyuan Dou, Binlin Cui, Guomin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

The biochar-assisted water electrolysis (BAWE) is a promising method for clean biomass utilization and hydrogen production. But it is limited by the slow anode biochar oxidation reaction (BOR). To enhance the BOR, the mediator of Fe2+/Fe3+ or NO2-/NO3- was added to the pyrolytic biochar (PB) and tested using electrochemical methods. Both Fe2+ and NO2- showed stronger oxidation activity than Fe3+ and NO3-, and thereby presented more significant enhanced role on BOR, including the reduction in onset potential and the enlargement of current density. Fe2+/Fe3+ existence resulted in the five-step mechanism such as adsorption, redox reaction in solution, oxidation at electrode surface, and passive films formation on the biochar surface. 0.5 mol/L or less of Fe2+/Fe3+ was suggestable, while the lower acid concentration was necessary to avoid side reaction with NO2- existence. The Fe2+/Fe3+ acted as catalysts due to the almost unchanged total iron ions during continuous BAWE process, whereas a high consumption of NO2- occurred. The cathode hydrogen production was less influenced by mediator and showed comparable with the theoretical value of Faraday's law. In addition, the activation energy of BOR was significantly reduced with Fe2+ and NO2- mediation. The present work provides a favorable strategy for improving BOR and energy-saving production of hydrogen via BAWE process.

关键词： Hydrogen Biochar-assisted water electrolysis (BAWE) Biochar oxidation reaction (BOR) Ions mediator Kinetics

来源：评论

学校读者我要写书评

暂无评论

Aerodynamic analysis of a novel pitch control strategy and parameter combination for vertical axis wind turbines

引用

RENEWABLE ENERGY 2023年第1期216卷

作者： Zhang, Qiang Bashir, Musa Miao, Weipao Liu, Qingsong Li, Chun Yue, Minnan Wang, Peilin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Liverpool John Moores Univ Offshore & Marine LOOM Res Inst Liverpool Logist Byrom St Liverpool L3 3AF England

The performance of a vertical axis wind turbine (VAWT) deteriorates at low tip speed ratios (TSR) and it is mainly characterized by flow separation and dynamic stall. Several mitigating techniques have been developed recently based on flow separation and dynamic stall research activities. One of such techniques is the use of blade pitch angle control, which shows very promising optimal performance in VAWTs. However, its adaptation for periodic variation of the angle of attack remains an important issue that needs to be addressed urgently. Therefore, this paper proposes a novel pitch control strategy based on the VAWT-shape pitch motion to achieve blade dynamic pitch with the rotational parameters (TSR and azimuth angle). The pitch scale factor (& mu;) is introduced to proportionally vary the angle of attack. High accuracy computational fluid dynamics (CFD) methods are used to simulate dynamic changes in pitch angle, flow field and vortex shedding vorticity, with the turbulence modelled using the SST k-& omega;model. The results show that a 146% increase in power coefficient can be achieved using a & mu;of 0.3 at TSR of 1.25. Additionally, the use of dual pitch scale factors (dpsf) in the windward and leeward regions causes intense transient torque fluctuations at 0 & DEG;(360 & DEG;) and 180 & DEG;azimuths due to a breaking distance in pitch angular velocity at these azimuths. Adding a weight function into the fitting process of the dpsf pitch curve effectively minimize these fluctuations.

关键词： Vertical axis wind turbines Pitch control strategy Pitch angular velocity Aerodynamic analysis

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：