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A simple analytical model to predict liquid unloading in the horizontal gas well

Journal of Hydrodynamics 2021年第5期33卷 1056-1064页

作者： Zhi-bin Wang Jin-quan Ling Tian-li Sun Hong-yan Shi Guo Zhu State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChendu 610500China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China No 2 Gas Production PlantSouthwest Oil and Gas CompanySINOPECLangzhong 637400China Infrastructure Department Southwest Oil and Gas CompanySINOPECChengdu 610041China

An accurate prediction of the critical gas velocity for the liquid loading is of great importance for operators to select the tubing diameter for the newly drilled gas wells,or to optimize the production rate for production *** is clear from previous experimental studies of the liquid entrainment rate in the gas core that the liquid is mainly carried in the form of film under the critical condition of the liquid loading *** is more reasonable to establish a mathematical model based on the film reversal rather than based on the droplet *** our previous paper entitled“Prediction of the critical gas velocity of liquid unloading in the horizontal gas well”,a new analytical model was established based on the force balance between the gas-liquid interfacial friction force and the bottom film gravity,but the model is not very convenient to use because of the complexity of calculating the average film *** the present study,a new method is proposed to calculate the average film thickness from the bubble drift velocity in the mixture,so the new analytical model becomes much easier to *** new analytical model is evaluated against 103 sets of experimental data,the data in 124 vertical gas wells and one horizontal gas ***,the effect ofthe liquid loading on the production of the horizontal gas well is also analyzed.

关键词： Horizontal gas well inclined annular flow liquid-film thickness liquid unloading

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Electromagnetic Effects and Accurate Wall-Temperature Measurement Method Under Directly Electric Heating Mode

SSRN

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SSRN 2022年

作者： Lei, Xianliang Liu, Yunfan Liu, Shuhan Li, Debiao Gou, Lingtong Li, Yusheng State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

By directly imposed electrical energy on metal materials with low voltage but high current to generate Joule heat is an effective energy conversion method. The corresponding temperature will quickly reach the predetermined value. It is also an effective way to achieve homogeneous heating or local non-uniform heating in the heterogeneous conductive elements, thus directly electric heating is widely used in scientific experiments and industrial practices. However, different direct Electrical heating method (i.e., Direct-Current or Alternating Current heating) will lead to different power losses and the interference on the sensor, results in inconsistent temperature distribution or inaccurate temperature, even under the condition with Power frequency (f= 50 Hz or 60 Hz). In the present paper, the skin effect and eddy current in different metal materials with variable frequency and different section-shapes have been analyzed by electromagnetic coupling simulation. Meanwhile, two comparative experimental investigations on temperature measurement methods with DC and AC heating have been implemented. It is found that the measured temperature by AC heating is always lower than that of DC heating effected by skin effect and mutual inductance effect, the skin depth in four common used materials is: Iron © 2022, The Authors. All rights reserved.

关键词： Temperature measurement

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Front tracking simulation of droplet displacement on solid surfaces by soluble surfactant-driven flows

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Physical Review Fluids 2024年第1期9卷 014002-014002页

作者： Xinglong Shang Zhengyuan Luo Bofeng Bai Long He Guoqing Hu Hangzhou Institute of Technology Xidian University Hangzhou 311200 China Department of Engineering Mechanics and State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang University Hangzhou 310027 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China College of Mechanical and Electrical Engineering Shaanxi University of Science and Technology Xi'an 710021 China

We provide comprehensive numerical insights into the displacement of droplets subject to soluble surfactant-driven flows. The effects of soluble surfactants on the dynamics of moving contact lines are introduced by the surfactant-dependent generalized Navier boundary condition. We show that surfactant transport significantly influences the displacement patterns of droplets on solid surfaces, affecting both the equilibrium state of the sliding motion and the critical conditions for detachment. In particular, a linear increase in the displacement velocity of a droplet with the dimensionless adsorption depth K is observed. This rate of increase is more pronounced at higher elasticity numbers, as evidenced by a more significant increase in the advancing contact angle. The critical condition for droplet detachment depends on the surfactant's ability to swiftly adsorb from the bulk and replenish at interfaces, which is improved as the Biot number Bi or K increases. Adsorption is enhanced by an increase in Bi, resulting in a decrease in the required time td for droplet detachment. However, this enhancement effect becomes nonmonotonic at high Bi values. In contrast, consistently increasing the bulk Peclet number decreases td, eventually approaching the convection limit where the Marangoni-induced drag force ceases to increase. In addition, surfactant transfer near the moving contact line at a moderate Damköhler number restricts the motion of the advancing contact lines, promoting droplet detachment. For all detachment scenarios, we find that detachment necessitates a critical effective capillary number, and an increase in this number results in an exponential decline in td.

关键词： Contact line dynamics Drop & bubble phenomena Marangoni convection Surface tension effects

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A new strategy to produce calcium carbide-acetylene from integrated multi-level low carbon construction driven by biomass

A new strategy to produce calcium carbide-acetylene from int...

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作者： Wang, Hongxia Li, Xiaoli Wu, Zhen Shen, Wei Chen, Kai Hong, Bingqing Zhang, Zaoxiao School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow in Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi'an710049 China Co. Ltd Level 10-15 Block A Sunland International No.999 Zhouhai Road Pudong New Zone Shanghai200131 China

A highly efficient and clean biomass energy-based calcium carbide-acetylene production system, including low-carbon energy supply, solid waste recycling and cascade utilization of waste heat, has been developed for the conventional energy-intensive and highly polluting fossil fuel-dependent calcium carbide industry. This system supplies the carbide-acetylene production plant with energy from the gasification of biomass and converts the plant's solid waste carbide slag into the calcium feedstock required by the plant. The waste heat from the plant's high-temperature exhaust gases is recycled and used via the multi-stage heat exchange, so that the energy cascade conversion and utilization is achieved. A simulation model of the plant is created in Aspen Plus, and a mathematical model for the biomass gasification process and cycle compensation of the calcium source through the Fortran language is written and embedded. When calculating the carbon consumption and CO2e emissions of the system, it was found that the carbon consumption and CO2e emissions of the conventional process were 5.43 t Coal·t−1C2H2 and 2.25 t CO2e·t−1C2H2, respectively. However, the carbon consumption of the new process was reduced by 65.19%, and carbon emissions by 27.24% in comparison. The energy analysis shows that the energy efficiency of the system is 36.21% for the conventional process and 44.82% for the new processes. The exergy analysis of the effective energy shows that the exergy efficiency of the new process is 73.20%, which is 52.98% better than that of the conventional process. Introduction of an index, the levelized income of acetylene product (LIOA), to characterize the product income of the system. When the price of acetylene is between 2.23 $/kg and 4.19 $/kg, the LIOA for the conventional and the new processes are 1.41 $/kg to 3.38 $/kg and − 1.28 $/kg to 0.68 $/kg, respectively. It is worth noting that the critical price (PCC2H2) for products generating net revenue from the new pro

关键词： Biomass

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Effect of Mixer Structure on Liquid Film Formation and Nox Conversion Efficiency in Selective Catalytic Reduction System

SSRN

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SSRN 2022年

作者： Fu, Hang Huang, Zuohua Tang, Chenglong State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Selective Catalytic Reduction as an efficient technology to reduce NOx emission has been widely applied in exhaust aftertreatment system. However, the reductant injection causes inevitable impingement on the exhaust pipe and mixer surface and the liquid film will be generated. In this paper, the simulation of a double-blade mixer (Mixer 1) is verified by a bench test and other three kinds of mixer structures (baffle mixer: Mixer 2, blade-baffle mixer: Mixer 3, and blade mixer: Mixer 4) are simulated. The effect of the mixer structures on the liquid film formation, the pressure drop, the flow and temperature distribution after the mixers and ultimately the NOx conversion efficiency are investigated. Results show that the liquid film is prone to form and accumulate at the connection region between the mixer and exhaust pipe, and liquid film tends to develop with the flow direction. Mixer 2 and Mixer 4 shows smaller liquid film area about 15 cm2. The temperature distribution in four types of mixers shows negligible difference (within 4 °C). NH3 mass fraction distribution uniformity and pressure drop shows a trade-off relationship. For the vertical injection system, it is found Mixer 3 gets the worst NOx conversion efficiency, 57%, and Mixer 2 shows better NOx conversion efficiency, 78%. The paper are supportive to the SCR mixer selection and design. © 2022, The Authors. All rights reserved.

关键词： Computational fluid dynamics

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Experimental Study on Frost Crystal Morphologies and Frosting Characteristics Under Different Working Pressures

SSRN

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SSRN 2022年

作者： Lai, Tianwei Liu, Xue Dong, Xiaojun Qiang, Mingchen Yan, Shaohang Hou, Yu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

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 are evaluated under different air parameters and temperatures of cooling surface. The vertical growth and lateral distribution of frost crystals are related strongly 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. © 2022, The Authors. All rights reserved.

关键词： Working pressure

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Improving sampling depth of laser speckle imaging by topical optical clearing:A theoretical and in vivo study

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Journal of Innovative Optical Health Sciences 2020年第2期13卷 33-43页

作者： D.Li Y.Zhang B.Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049P.R.China

The effect of optical cleaning method combined with laser speckle imaging(LSI)was discussed to improve the detection depth of LSI due to high scattering characteristics of skin,which limit its clinical application.A double-layer skin tissue model embedded with a single blood vessel was established,and the Monte Carlo method was used to simulate photon propagation under the action of light-permeating agent.808 nm semiconductor and 632.8 nm He–Ne lasers were selected to study the e®ect of optical clearing agents(OCAs)on photon deposition in *** show that the photon energy deposition density in the epidermis increases with the amount of tissue°uid replaced by *** with glucose solution,polyethylene glycol 400(PEG 400)and glycerol can considerably increase the average penetration depth of photons in the skin tissue,thereby raising the sampling depth of the *** the action of glycerol,PEG 400,and glucose,the average photon penetration depth is increased by 51.78%,51.06%,and 21.51%for 808nm,68.93%,67.94%,and 26.67%for 632.8 nm lasers,*** vivo experiment by dorsal skin chamber proves that glycerol can cause a substantial decrease in blood°ow rate,whereas PEG 400 can signicantly improve the capability of light penetration without a®ecting blood velocity,which exhibits considerable potential in the monitoring of blood°ow in skin tissues.

关键词： Laser speckle image topical optical clearing imaging depth Monte-Carlo simulation dorsal skin experiment

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Improved filtered mesoscale interphase heat transfer model

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Particuology 2021年第4期19卷 176-186页

作者： Yu Li Yaxiong Yu Chi Zhang Zheqing Huang Qiang Zhou School of Chemical Engineering and Technology Xi’an Jiao Tong UniversityXi’an 710049China AVIC Xi’an Flight Automatic Control Research Institute Xi’an 710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiao Tong UniversityXi’an 710049China

Mesoscale structures that form in gas-solid flows considerably affect interphase heat transfer.A filtered interphase heat transfer model accounts for the effects of unresolved mesoscale structures is required in coarse-grid *** the literature,researchers obtain the filtered interphase heat transfer coefficient using a correction(Q)to the microscopic interphase heat transfer *** models are based on filtered data in the range 01 is *** percentage can reach approximately 20%when the dimensionless filter size is smaller than 1.028(66.7×the particle diameter).We proposed an improved filtered interphase heat transfer model by considering the data in the range Q<0 and Q>*** evaluated the predictive power of our model in an a priori *** model has much better performance than other models when the dimensionless filter size△<8.222.

关键词： Gas-solid flows Two-fluid model Interphase heat transfer Filtered model Mesoscale

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Numerical Investigation on the Radiation Performance of a Crisscross Liquid Droplet Radiator in Space Under Different Operating Conditions

SSRN

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SSRN 2022年

作者： Zhu, Maoguo Sha, Zhaoyang Zhao, Quanbin Chong, Daotong Chen, Weixiong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China

Crisscross liquid droplet radiator (LDR) is a promising solution for the heat dissipation of large-power space structures. In this study, a three-dimensional steady numerical simulation of the radiation performance of crisscross LDR in space under different operating conditions was conducted. Significantly, the radiation interaction between adjacent droplet planes was introduced into the radiation model to accurately compute the energy radiated by the crisscross droplet sheet. Simulation results indicated the radiation performance of crisscross droplet sheet deteriorated with an increase in the nonuniformity of droplet planes arrangement and hence droplet planes uniformly arranged were required for a good crisscross LDR. Moreover, there existed a critical droplet sheet angle of 72° where the pressure disturbance frequency almost had no influence on the radiation performance of crisscross LDR. For certain pressure disturbance frequency, decreasing the droplet sheet angle can expand the available operational pressure difference range. The radiation performance of crisscross LDR with high initial droplet temperature was more sensitive to the changes in droplet sheet angle than that with low initial droplet temperature. Finally, the optimal working medium collocation scheme and droplet sheet configuration for crisscross liquid metal LDR were proposed. Given the lightweight and efficiency of crisscross liquid metal LDR, the collocation scheme of working medium including tin and lithium can be adopted and the droplet sheet angle should be designed as 15°. The present work can provide significant guidance for selecting suitable operating conditions for droplet generators to optimize the thermal design of a crisscross LDR. © 2022, The Authors. All rights reserved.

关键词： Drops

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Experimental Investigation on Separation Characteristics of Gas-Liquid Two-Phase flow Around the Perforated Tube

SSRN

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SSRN 2022年

作者： Wang, Jinzhi Xie, Xiangdong Wang, Yechun Xu, Qiang Wang, Jiang Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

The flow around cylinder is widely used in industrial applications. In this study, the separation characteristics of gas-liquid two-phase flow around a perforated tube are investigated experimentally. The interface fluctuation process of the gas pocket and liquid slug periodic separation around the perforated tube is presented intuitively using a high-speed camera. The mean value and standard deviation of the void fraction in the wake region are independent of the inlet liquid flow rate. When the flow pattern is plug flow, the air separation efficiency first decreases and then increases with an increase in the inlet void fraction;the separation efficiency increases monotonically when the flow pattern is slug flow. The separation purity and total pressure drop increase with increasing inlet void fraction. Based on the principle of minimum kinetic energy, methods for predicting the void fraction in the wake region, separation purity, air separation efficiency and pressure drop have been developed. The new correlations are based on the Weber number and liquid-phase Reynolds number that are also controlling dimensionless group in determining the void fraction, separation efficiency and pressure drop. The prediction accuracies of the void fraction and separation purity are within ±10% and the prediction accuracies of the separation efficiency and pressure drop are within ±20%, which provides an accurate prediction of the separated flow around the perforated tube. © 2022, The Authors. All rights reserved.

关键词： Void fraction

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