检索结果-内蒙古大学图书馆

Investigation and prediction of severe slugging frequency in pipeline-riser systems

CHEMICAL engineering SCIENCE 2018年 184卷 72-84页

作者： Zhou, Hongliang Guo, Liejin Yan, Han Kuang, Shicai Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Severe slugging is one of the flow assurance concerns in oil and gas industry because of the undesired fluctuations of pressure and flow rates in the system. Knowledge of severe slugging frequency is essential for the receiving facility design. However, unlike the considerable investigations of normal slug frequency in horizontal and inclined pipes, little work has been done to predict severe slugging frequency. In this work, an experimental study of air-water two-phase flow was conducted in a long pipeline-riser system. According to the riser pressure drop signals and the power spectral density (PSD) distributions, flow patterns were classified into classical severe slugging, transitional severe slugging, oscillating flow and stable flow. The effect of riser-top choking on classical and transitional severe slugging frequency were analyzed. Based on a broad range experimental database from ten flow loops, the effect of dimensionless pipeline length on severe slugging frequency was analyzed and an empirical correlation was developed to predict severe slugging frequency. Good matches with literature data demonstrated the validation of the empirical correlation. The severe slugging frequency correlation was applied to predict severe slugging length and derive a new transition criterion between classical severe slugging and transitional severe slugging in the flow pattern map. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Severe slugging frequency Riser-top choking Empirical correlation Transition criterion

来源：评论

学校读者我要写书评

暂无评论

Dynamic modeling and operation optimization for the cold end system of thermal power plants during transient processes

引用

ENERGY 2018年 145卷 734-746页

作者： Wang, Chaoyang Liu, Ming Zhao, Yongliang Qiao, Yongqiang Chong, Daotong Yan, Junjie Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

This paper focuses on the dynamic modeling of the cold end system of a thermal power plant and its operation optimization during cycling load processes. A revised logarithm mean temperature difference is recommended to calculate the heat transfer quantity between exhaust steam and condenser tubes. With this method, a condenser model is developed with a maximum relative error limited within 3%. Coupled with a turbo-generator, a condenser, water pumps, and a cooling tower, a closed cooling system model is established. The total power supply (TPS) during cycling load is calculated and analyzed to optimize the operation during transient processes. A method for obtaining the maximum value of TPS is provided and used to calculate the optimal operating load rate points for switching pumps (OPSP). OPSP increases with the cycling load rate (V-e) during loading up processes decreases with V-e during loading down processes. When V-e is identical, OPSP declines with the ambient temperature for the loading up and down processes. TPS during transient processes is relevant with the switching pump load rate. The maximum value of difference in TPS with different switching pump periods is 691.4 (kW h) for switching pump numbers from 3 to 2 during loading down processes. (C) 2017 Elsevier Ltd. All rights reserved.

关键词： Thermal power plant Cold end system Dynamic modeling Cycling operation Energy consumption

来源：评论

学校读者我要写书评

暂无评论

Parametric effect investigation on surface heat transfer performances during cryogen spray cooling

引用

APPLIED THERMAL engineering 2018年 143卷 767-776页

作者： Tian, Jia-Meng Chen, Bin Zhou, Zhi-Fu Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Cryogen spray cooling (CSC) has been a widely used auxiliary tool in laser dermatology such as port wine stain to prevent unspecific thermal injury due to laser energy absorption by the melanin in the epidermis. The present paper presents an experimental research on the effect of ambient temperature, relative humidity, and initial substrate temperature on heat transfer performances during R134a spray cooling. Results demonstrated that the cooling capability of R134a spray cooling can be obtained with small ambient temperature (T-a = 10 degrees C) and relative humidity (RH = 25%). Further investigation of cooling mechanism was conducted by studying the temporal and radial heat transfer distributions with different spray distances and nozzles. The heat transfer distribution presented large non-uniformity along radial locations. Two uniform cooling sub-regions of 0 <= r < 2 mm and 6 mm <= r < 10 mm were found under the spray distance of 30 mm and nozzle with an inner diameter of 1.0 mm. The heat transfer barrier was produced due to indirect contact between cold droplets and the substrate surface caused by bubbles and heat transfer is weakened by the low thermal conductivity of these bubbles.

关键词： Cryogen spray cooling Surface heat transfer Ambient temperature Relative humidity 2D filter solution

来源：评论

学校读者我要写书评

暂无评论

Atomization and surface heat transfer characteristics of cryogen spray cooling with expansion-chambered nozzles

引用

INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 2018年 121卷 15-27页

作者： Wang, Xin-Sheng Chen, Bin Zhou, Zhi-Fu Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Cryogen spray cooling (CSC) is commonly applied in laser dermatology to protect the epidermis from thermal damage. Many efforts have attempted to improve the cooling capacity of CSC, among which the use of expansion-chambered nozzles is an effectively simple method with considerable potential. This study examined the influences of the expansion-chambered nozzle structure, including the ratios of inlet nozzle diameter to discharge nozzle diameter and of chamber diameter to discharge nozzle diameter on R134a and R404A spray cooling. Fifteen transparent expansion-chambered nozzles with the expansion chamber aspect ratio of 1.0, chamber diameter to discharge nozzle diameter ratios of 5.0-10.0, and inlet nozzle diameter to discharge nozzle diameter ratios of 0.6-1.4 were tested. The internal flow pattern inside the expansion chamber, external spray pattern, and surface heat transfer characteristics of cryogen spray using different nozzles, including the straight-tube nozzle, were investigated. The structure of the expansion chamber was found to have an important effect on the spray patterns and cooling characteristics. The spray radius obviously decreased when the expansion-chambered nozzles were used, and the spray pattern became narrower as the ratio of chamber diameter to discharge nozzle diameter increased. By contrast, the increase in ratio of two nozzle diameters enlarged the spray radius. Surface temperature and heat flux with different nozzles and cryogens showed a similarity, and correlations of surface temperature and heat flux were proposed. The introduction of expansion chambered nozzles could effectively improve the spray cooling capacity. The minimum average surface temperature during the fully developed spray period could be reached for both R134a spray and R404A spray by an expansion-chambered nozzle with a chamber diameter to discharge nozzle diameter ratio of roughly 5.0 and an inlet nozzle diameter to discharge nozzle diameter ratio of roughly 0.6. (C)

关键词： Cryogen spray cooling Cooling capacity Expansion-chambered nozzle R134a R404A flow visualization

来源：评论

学校读者我要写书评

暂无评论

Experimental investigation on effect of surface strengthening process and roughness on water droplet erosion behavior in turbomachinery

引用

TRIBOLOGY INTERNATIONAL 2021年 153卷 106647-106647页

作者： Di, Juan Wang, Shun-sen Yan, Xiao-jiang Cai, Liu-xi Xie, Yong-hui Taiyuan Univ Sci & Technol Coll Mech Engn 66 Waliu Rd Taiyuan 030024 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Inst Turbomachinery 28 Xianning West Rd Xian 710049 Peoples R China Xi An Jiao Tong Univ Sch Chem Engn & Technol 28 Xianning West Rd Xian 710049 Peoples R China

In this paper, the water droplet erosion (WDE) performance of a typical martensitic blade material 17-4 PH (0Cr17Ni4Cu4Nb), surface strengthened laser cladding stellite and brazed stellite alloy is studied based on high-speed water jet test system. The WDE resistances from high to low are the brazed stellite alloy, laser cladding stellite alloy and 17-4 PH. For the same material, the greater the initial roughness of the target surface, the more severe is the WDE damage. Improving the surface finish of the target is conducive to the diversion and expansion of the liquid flow, prolonging the incubation period, and thus enhancing the WDE resistance.

关键词： Water droplet erosion Surface roughness Stellite alloy Eroded micro-morphologies

来源：评论

学校读者我要写书评

暂无评论

Experimental investigation on effect of ethanol and di-ethyl ether addition on the spray characteristics of diesel/biodiesel blends under high injection pressure

引用

FUEL 2018年 218卷 1-11页

作者： Zhan, Cheng Feng, Zehao Ma, Wen'an Zhang, Mingzhi Tang, Chenglong Huang, Zuohua Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

In this work, a comprehensive experimental investigation on spray characteristics of four blended fuels, including diesel (D100), diesel-biodiesel (DB), diesel-biodiesel-ethanol (DBE), and diesel-biodiesel-diethyl ether (DBDE) has been conducted by using high pressure common rail injection system (up to 200 MPa). The transient spray behavior under various conditions was recorded by high speed photography with scattering light illumination. It is shown that higher injection pressure significantly accelerates the spray tip penetration (STP) evolution due to increased inertia of spray while increase in ambient pressure reduces the STP evolution due to higher gas resistance. With the addition of diethyl ether (DEE) into biodiesel, the STP of blended fuel tends to go down and corresponding projected area increases a lot when compared to DB. By means of particle droplet image analysis (PDIA) optical diagnostic method, spray microscopic parameters such as Sauter Mean Diameter (SMD), droplet diameter distribution probability curve, cumulative volume curve and characteristic diameter have been investigated. Results show that both the injection pressure and ambient pressure have significant influence on the spray microscopic characteristics. In addition, for fixed injection pressure and ambient pressure, when DEE is added into DB blends, the number fraction of smaller droplets increases, though the statistic diameter with peak probability is fixed at a certain value. Furthermore, SMD of the four tested fuels decreases sequentially in the order of DB, D100, DBE, and DBDE, indicating that DEE addition favors the atomization process.

关键词： Diesel Biodiesel DEE Atomization STP SMD

来源：评论

学校读者我要写书评

暂无评论

Mass transfer characteristics of pipeline leak-before-break in a nuclear power station

引用

APPLIED THERMAL engineering 2018年 142卷 194-202页

作者： Yin, Songtao Weng, Yu Song, Zichen Cheng, Bo Gu, Hongfang Wang, Haijun Yao, Jianan Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

This paper aims to develop a correlation for pressure undershoot and revises the hypotheses of nucleation inception in the two-phase critical flow model. The theories of rapid depressurization and isothermal bubble growth were used to construct a modified two-phase critical flow model for leak-before-break analysis. The modified model predictions exhibit strong similarities with the experimental values compared with the Moody and Henry-Fauske models, with prediction deviations of less than 8.9% in the inter-granular stress corrosion crack. The effects of the inlet conditions on the nucleation inception point, as well as the distribution characteristics of the mass quality and void fraction along the channel, were investigated to explore the mass transfer process.

关键词： Leak-before-break Two-phase critical flow Nucleation inception point Mass transfer Rapid depressurization

来源：评论

学校读者我要写书评

暂无评论

Study on identification method of heat transfer deterioration of supercritical fluids in vertically heated tubes

引用

INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 2018年第PartB期127卷 674-686页

作者： Zhang, Qian Li, Huixiong Lei, Xianliang Zhang, Jun Kong, Xiangfei Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Prediction of the heat transfer of supercritical fluids (SCFs), especially for heat transfer deterioration (HTD), is highly significant to the design and safe operation of supercritical boilers and advanced nuclear systems. To achieve higher predictive accuracy, heat transfer datasets of SCFs are usually classified as HTD cases and non-HTD cases using certain HTD identification methods, and prediction models, including empirical correlations and criteria of HTD occurrence, have been separately developed for HTD cases and non-HTD cases. Therefore, the rationality of HTD identification methods are crucial to the data classification and further development of high-precision prediction models but is seldom discussed in research. This paper first summarizes the existing identification methods of HTD to SCFs, and respective heat transfer datasets of supercritical water (SCW) and CO2 (SCCO2) are compiled. Based on these data sets, the accuracy of existing methods in identifying HTD cases and non-HTD cases is evaluated. The results show that, the most common identification method (Nu/Nu(db) < 0.3) can mistake typical nonHTD case for HTD case and cannot reflect the actual location where HTD occurs. The Lokshin et al. method and Zhang et al. method (htc/ht(co) < 1.0) can accurately recognize HTD cases but are prone to error in detecting non-HTD cases. It is believed that the reference value representing normal heat transfer is the key to judging the heat transfer state of SCFs, and should be considered specifically in the pseudo phase -change influenced region. Finally, an improved identification method of HTD suitable for SCW and SCCO2 is proposed. Compared with previous methods, the new method shows favorable accuracy in discerning both HTD cases and non-HTD cases, and is helpful for classifying heat transfer cases and developing precise heat transfer correlations and HTD criteria of SCFs. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Definition of heat transfer deterioration Identification method of heat transfer deterioration Criterion of heat transfer deterioration Pseudo-critical region Supercritical fluids

来源：评论

学校读者我要写书评

暂无评论

Energy and exergy analyses of circulatory flash evaporation of aqueous NaCl solution

引用

DESALINATION 2018年 436卷 81-90页

作者： Wang, Yu He, Qi Yang, Qingzhong Zhang, Dan Liu, Ming Yan, Junjie Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

In present study, an experimental system for circulatory flash evaporation was designed and built. Energy and exergy analyses of circulatory flash process were carried out. Basing on the first law of thermodynamics, the gained output ratio of circulatory flash evaporation (GOR(CFE)) was defined as an energy ratio between latent heat carried away by flash steam and input excess energy of working fluids. The performance ratio of circulatory flash evaporation (PRCFE) was defined as the mass flow rate divided by exergy destruction rate. The Effects of main factors, namely, superheat degree, circulating flow rates, equilibrium pressure, initial water level and salinity on GOR(CFE) and PRCFE were studied. Results suggested that GOR(CFE) decreased rapidly at the initial stage, then increased with the increase of superheat degree and became flat eventually. The optimal superheat degree was determined wherein the maximum performance ratio was reached. According to the comparison of gained output ratio and performance ratio, the maximum performance ratio was obtained when gained output ratio was great enough and temperature difference was minimal.

关键词： Circulatory flash evaporation Exergy analysis Performance ratio Gained output ratio Aqueous NaCl solution

来源：评论

学校读者我要写书评

暂无评论

Ethylene production via photocatalytic dehydrogenation of ethane using LaMn1-xCuxO3

引用

NATURE ENERGY 2024年第6期9卷 750-760页

作者： Song, Rui Zhao, Guanshu Restrepo-Florez, Juan Manuel Perez, Camilo J. Viasus Chen, Zhijie Ai, Chaoqian Wang, Andrew Jing, Dengwei Tountas, Athanasios A. Guo, Jiuli Mao, Chengliang Li, Chaoran Shen, Jiahui Cai, Guangming Qiu, Chenyue Ye, Jessica Fu, Yubin Maravelias, Chistos T. Wang, Lu Sun, Junchuan Xu, Yang-Fan Li, Zhao Loh, Joel Yi Yang Nguyen, Nhat Truong He, Le Zhang, Xiaohong Ozin, Geoffrey A. Soochow Univ Inst Funct Nano & Soft Mat FUNSOM Suzhou Peoples R China Univ Toronto Dept Chem Solar Fuels Grp Toronto ON Canada Soochow Univ Jiangsu Key Lab Adv Negat Carbon Technol Suzhou Peoples R China Univ Wisconsin Dept Chem & Biol Engn Madison WI USA Univ Florida Dept Chem Engn Gainesville FL USA Xi An Jiao Tong Univ Int Res Ctr Renewable Energy State Key Lab Multiphase Flow Power Engn Xian Peoples R China Univ Toronto Dept Chem Engn & Appl Chem Toronto ON Canada Soochow Univ Jiangsu Key Lab Carbon Based Funct Mat & Devices Suzhou Peoples R China Univ Toronto Dept Mat Sci & Engn Toronto ON Canada Max Planck Inst Microstruct Phys Halle Germany Princeton Univ Dept Chem & Biol Engn Princeton NJ USA Princeton Univ Andlinger Ctr Energy & Environm Princeton NJ USA Chinese Univ Hong Kong Shenzhen Sch Sci & Engn Shenzhen Peoples R China Concordia Univ Gina Cody Sch Engn & Comp Sci Dept Chem & Mat Engn Montreal PQ Canada

Industrial-scale ethylene production occurs primarily by fossil-powered steam cracking of ethane-a high-temperature, high-energy process. An alternative, photochemical, pathway powered by sunlight and operating under ambient conditions could potentially mitigate some of the associated greenhouse gas emissions. Here we report the photocatalytic dehydrogenation of ethane to ethylene and hydrogen using LaMn1-xCuxO3. This perovskite oxide possesses redox-active Lewis acid sites, comprising Mn(III) and Mn(IV), and Lewis base sites, comprising O(-II) and OH(-I), collectively dubbed surface-frustrated Lewis pairs. We find that tuning the relative proportions of these sites optimizes the activity, selectivity and yield for ethane dehydrogenation. The highest ethylene production rate and ethane conversion achieved were around 1.1 mmol g(-1) h(-1) and 4.9%, respectively. We show a simple outdoor prototype to demonstrate the viability of a solar ethylene process. In addition, techno-economic analysis revealed the economic potential of an industrial-scale solar ethylene production from ethane.

关键词： Ethane

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：