Vol.16, No.3, 2020-Table of Contents
  • Development and Application of a Production Data Analysis Model for a Shale Gas Production Well
  • Abstract This paper presents the development and application of a production data analysis software that can analyze and forecast the production performance and reservoir properties of shale gas wells. The theories used in the study were based on the analytical and empirical approaches. Its reliability has been con- firmed through comparisons with a commercial software. Using transient data relating to multi-stage hydraulic fractured horizontal wells, it was confirmed that the accuracy of the modified hyperbolic method showed an error of approximately 4% compared to the actual estimated ultimate recovery (EUR). On the basis of the developed model, reliable productivity forecasts have… More
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  • Experimental Investigation on the Pressure Propagation Mechanism of Tight Reservoirs
  • Abstract Low permeability tight sandstone reservoirs have a high filtrational resistance and a very low fluid flow rate. As a result, the propagation speed of the formation pressure is low and fluid flow behaves as a non-Darcy flow, which typically displays a highly non-linear behavior. In this paper, the characteristics and mechanism of pressure propagation in this kind of reservoir are revealed through a laboratory pressure propagation experiment and through data from an actual tight reservoir development. The main performance mechanism is as follows: A new pressure cage concept is proposed based on the pressure variation characteristics of the laboratory experiments.… More
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  • Impacts of Heat Flux Distribution, Sloping Magnetic Field and Magnetic Nanoparticles on the Natural Convective Flow Contained in a Square Cavity
  • Abstract In the present paper, the effect of the heat flux distribution on the natural convective flow inside a square cavity in the presence of a sloping magnetic field and magnetic nanoparticles is explored numerically. The nondimensional governing equations are solved in the framework of a finite element method implemented using the Galerkin approach. The role played by numerous model parameters in influencing the emerging thermal and concentration fields is examined; among them are: the location of the heat source and its lengthH*, the magnitude of the thermal Rayleigh number, the nanoparticles shape and volume fraction, and the Hartmann number. It… More
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  • A Numerical Investigation into the Influence of Electrode-Related Parameters on Electroosmotic Mixing and Related Mechanisms
  • Abstract Electroosmosis is an effective method for liquid mixing. It is associated with the motion of a liquid in a microchannel induced by an applied electric field. In this manuscript, a numerical model is elaborated and implemented for the case of a straight channel with a single electrode pair. In particular, the Navier-Stokes equation combined with the Convection-diffusion and Helmholtz-Smoluchowski equation are used to simulate the resulting flow field. The influence of various electrode parameters on the mixing efficiency and the related mechanisms are investigated. The numerical results show that a pair of eddies are produced alternately by the changing electric… More
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  • Effect of the Inclination Angle on Slippage Loss in Gas-Liquid Two-Phase Flow
  • Abstract The lifting efficiency and stability of gas lift well are affected by the socalled slippage-loss effect in gas-liquid two-phase flow. The existing studies on this subject have generally been based on vertical and horizontal wells. Only a few of them have considered inclined pipes. In the present work a new focused study is presented along these lines. More specifically, we use the non-slip pressure drop model with Flanigan’s fluctuation correction coefficient formula (together with the parameters of slippage density, slippage pressure drop and slippage ratio) to analyze the influence of the inclination angle on slippage loss for different conditions (different… More
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  • Experimental Analysis of the Performances of Unit Refrigeration Systems Based on Parallel Compressors with Consideration of the Volumetric and Isentropic Efficiency
  • Abstract The performances of a refrigeration unit relying on compressors working in parallel have been investigated considering the influence of the compressor volumetric efficiency and isentropic efficiency on the compression ratio. Moreover, the following influential factors have been taken into account: evaporation temperature, condensation temperature and compressor suction-exhaust pressure ratio for different opening conditions of the compressor. The following quantities have been selected as the unit performance measurement indicators: refrigeration capacity, energy efficiency ratio (COP), compressor power consumption, and refrigerant flow rate. The experimental results indicate that the system refrigeration capacity and COP decrease with a decrease in evaporation temperature, increase… More
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  • Influence of Logging Instrument Drag on Temperature Distribution in Horizontal Gas Wells
  • Abstract In order to clarify the influence of the instrument’s own drag on the temperature distribution in the horizontal gas wellbore in temperature logging. By constructing an indoor gas-liquid two-phase horizontal tube flow platform, the effects of the drag speed of the instrument on the temperature distribution in the wellbore were studied in the single-phase gas and gas-liquid two phases. In addition, during the process of instrument dragging, the influence of different perforation cluster opening methods and wellbore inclination on temperature distribution was also studied. The results show that the temperature fluctuation is reduced at higher drag speeds; Under a certain… More
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  • Sliding Mode Control of Hydraulic Pressure in Electro-Hydraulic Brake System Based on the Linearization of Higher-Order Model
  • Abstract The possibility to enhance the stability and robustness of electrohydraulic brake (EHB) systems is considered a subject of great importance in the automotive field. In such a context, the present study focuses on an actuator with a four-way sliding valve and a hydraulic cylinder. A 4-order nonlinear mathematical model is introduced accordingly. Through the linearization of the feedback law of the high order EHB model, a sliding mode control method is proposed for the hydraulic pressure. The hydraulic pressure tracking controls are simulated and analyzed by MATLAB/Simulink soft considering separately different conditions, i.e., a sine wave, a square wave and… More
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  • Analysis of Water Transport inside a Plant Xylem Vessel with Pitted Thickening
  • Abstract In this article, computational fluid dynamics (CFD) are used to explore the dynamics of water transport inside the pitted thickening of a plant xylem vessel. A pitted thickening model combined with the Bernoulli equation is used to analyze the influence of various factors (namely, the inner diameter, thickening width, thickening height, thickening spacing, number of laps and adjacent pit axial rotation). The pressure drop and the flow resistance coefficient are the variable parameters for our analysis. The results show that these two parameters are proportional to the thickening height and thickening width, and inversely proportional to the inner diameter, thickening… More
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  • Large Eddy Simulation of Gasoline-Air Mixture Explosion in Long Duct with Branch Structure
  • Abstract Gas explosion is a process involving complex hydrodynamics and chemical reactions. In order to investigate the interaction between the flame behavior and the dynamic overpressure resulting from the explosion of a premixed gasoline-air mixture in a confined space, a large eddy simulation (LES) strategy coupled with sub-grid combustion model has been implemented. The considered confined space consists of a long duct and four branches symmetrically distributed on both sides of the long duct. Comparisons between the simulated and experimental results have been considered with regard to the flame structure, flame speed and overpressure characteristics. It is shown that the explosion… More
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  • Simulation of the Thermal Environment and Velocity Distribution in a Lecture Hall
  • Abstract The rational design of heating ventilation and air conditioning systems is an important means to achieve energy conservation and sustainable development. The simulation of air-conditioning systems with finite element methods has gradually become an important auxiliary means of complex airspace design. In this paper, a k-ε turbulence model is used to conduct 3D simulations and optimize the summer air conditioning system of a lecture hall. Various conditions are considered in terms of fresh air temperature and flow rate towards the end to improve comfort. The approach used in this paper could also be used in the future as an auxiliary… More
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  • RANS Simulation for the Maneuvering and Control of a Suboff Submarine Model
  • Abstract Submarine maneuverability has been analyzed by means of computational fluid dynamics (CFD). This approach provides an alternative, accurate, and cost-effective method for simulating actual flow. The numerical results show that the numerical simulation of the viscous flow related to a moving submarine based on the RANS equation with a relevant turbulence model can not only provide rich flow field details such as flow separation, but also accurately predict its hydrodynamic performance. The present study indicates that CFD can be used to forecast the submarine’s maneuverability in the initial design stage. The present results will be used in the future as… More
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  • Numerical Simulation of Axial Inflow Characteristics and Aerodynamic Noise in a Large-Scale Adjustable-Blade Fan
  • Abstract Numerical simulation are conducted to explore the characteristics of the axial inflow and related aerodynamic noise for a large-scale adjustable fan with the installation angle changing from −12° to 12°. In such a range the maximum static (gauge) pressure at the inlet changes from −2280 Pa to 382 Pa, and the minimum static pressure decreases from −3389 Pa to −8000 Pa. As for the axial intermediate flow surface, one low pressure zone is located at the junction of the suction surface and the hub, another is located at the suction surface close to the casing position. At the outlet boundary,… More
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  • Numerical Study of High-Temperature Nonequilibrium Flow around Reentry Vehicle Coupled with Thermal Radiation
  • Abstract Accurate aerodynamic heating prediction is of great significance to current manned space flight and deep space exploration missions. The temperature in the shock layer surrounding the reentry vehicle can reach up to 10,000 K and result in remarkable thermochemical nonequilibrium, as well as considerable radiative heat transfer. In general, high-temperature flow simulations coupled with thermal radiation require appropriate numerical schemes and physical models. In this paper, the equations governing hypersonic nonequilibrium flow, based on a three-temperature model combined with a thermal radiation solving approach, are used to investigate the radiation effects in the reentry shock layer. An axisymmetric spherical case… More
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  • Influence of Steam and Sulfide on High Temperature Selective Catalytic Reduction
  • Abstract The influences of steam and sulfide on the efficiency of NOx reduction using ammonia (NH3) over the nanometer-class V-W/Ti catalyst in conditions of high temperature is experimentally investigated using a steady-flow reactor. The results showed that selective catalytic reduction (SCR) is inhibited by H2O at low temperature, but higher NO conversion efficiency is achieved at high temperature since the reaction of NH3 oxidized by O2 to NOx is inhibited by H2O. The activity of SCR is promoted by SO2 in the temperature range of 200~500° C, the NO conversion efficiency was improved to 98% from 94% by adding SO2. SCR… More
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  • CFD-Based Optimization of Hot Primary-Air Pipe Networks in Power Plant Milling Systems
  • Abstract A hot primary-air pipe system is the bridge connecting an air-preheater with a coal mill in power generation stations. The effective geometrical configuration of the pipe network greatly affects the air flow distribution and consequently influences the safe and economic operation of milling systems in power stations. In order to improve the properties of the air flow, in the present work the SIMPLEC method is used to simulate numerically the flow field for the original layout of the system. As a result, the internal mechanisms influencing the uneven pressure drop in each branch are explored and three optimization schemes are… More
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  • Numerical Investigations on the Impact of Turbulent Prandtl Number and Schmidt Number on Supersonic Combustion
  • Abstract The flow field inside the combustor of a scramjet is highly complicated and the related turbulent Prandtl and Schmidt numbers have a significant impact on the effective numerical prediction of such dynamics. As in many cases researchers set these parameters on the basis of purely empirical laws, assessing their impact (via parametric numerical simulations) is a subject of great importance. In the present work, in particular, two test cases with different characteristics are selected for further evaluation of the role played by these non-dimensional numbers: Burrows-Kurkov case and DLR case. The numerical results indicate that these parameters influence ignition location.… More
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  • Study on Buildings CCHP System Based on SOFC
  • Abstract The relationship among the working temperature, pressure and current density of a Solid oxide fuel cell (SOFC) and its output power and efficiency are analyzed in the framework of a theoretical model able to provide, among other things, the volt ampere characteristic curve. In particular, following the principle of temperature matching and cascade utilization, we consider a gas turbine (GT) and a LiBr absorption chiller to recycle the high-grade exhaust heat produced by the considered SOFC. This distributed total energy system is set up with the intent to meet typical needs of buildings for cooling, heating and power (CCHP). The… More
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