scholarly journals Real-gas Effect Accounted for by the Principle of Extended Corresponding States in Modeling Supersonic Kerosene Jet

2018 ◽  
Author(s):  
Ye Wang ◽  
Wei Yao ◽  
Xuejun Fan
Keyword(s):  
Corresponding States ◽  
Real Gas ◽  
Real Gas Effect ◽  
Extended Corresponding States ◽  
Gas Effect

Real Gas Effect on Gas Slippage Phenomenon in Shale

2021 ◽  
Author(s):  
Yufei Chen ◽  
Juliana Y. Leung ◽  
Changbao Jiang ◽  
Andrew K. Wojtanowicz
Keyword(s):  
Pore Size ◽  
Free Path ◽  
Mean Free Path ◽  
Real Gas ◽  
The Real ◽  
Gas Slippage ◽  
Real Gas Effect ◽  
Shale Reservoirs ◽  
Low Pressures ◽  
Gas Effect

Abstract The past decade has seen the rapid development of shale gas across the world, as the record-breaking success and on-going surge of commercial shale gas production in such unconventional reservoirs pose a tremendous potential to meet the global energy supply. However, questions have been raised about the intricate gas transport mechanisms in the shale matrix, of which the gas slippage phenomenon is one of the key mechanisms for enhancing the fluid transport capacity and, therefore, the overall gas production. Given that shale reservoirs are often naturally deposited in the deep underground formations at high pressure and temperature conditions (much deeper than most typical conventional deposits), the real gas effect cannot be ignored as gas properties may vary significantly under such conditions. The purpose of this study is thus to investigate the real gas effect on the gas slippage phenomenon in shale by taking into account the gas compressibility factor (Z) and Knudsen number (Kn). This study begins with a specific determination of Z for natural gas at various pressures and temperatures under the real gas effect, followed by several calculations of the gas molecular mean free path at in-situ conditions. Following this, the real gas effect on gas slippage phenomenon in shale is specifically analyzed by examining the change in Knudsen number. Also discussed are the permeability deviation from Darcy flux (non-Darcy flow) due to the combination of gas slippage and real gas effect and the specific range of pressure and pore size for gas slippage phenomenon in shale reservoirs. The results show that the gas molecular mean free path generally increases with decreasing pressure, especially at relatively low pressures (< 20 MPa). And, increasing temperature will cause the gas molecular mean free path to rise, also at low pressures. Knudsen number of an ideal gas is greater than that of a real gas; while lower than that of a real gas as pressure continues to rise. That is, the real gas effect suppresses the gas slippage phenomenon at low pressures, while enhancing it at high pressures. Also, Darcy’s law starts deviating when Kn > 0.01 and becomes invalid at high Knudsen numbers, and this deviation increases with decreasing pore size. No matter how pore size varies, this deviation increases with decreasing pressure, meaning that the gas slippage effect is significant at low pressures. Finally, slip flow dominates in the various gas transport mechanisms given the typical range of pressure and pore size in shale reservoirs (1 MPa < P < 80 MPa; 3 nm < d < 3000 nm). Gas transport in shale is predominantly controlled by the slippage effect that mostly occurs in micro- or meso-pores (10 to 200 nm). Moreover, considering the real gas effect would improve the accuracy for determining the specific pressure range of the gas slippage phenomenon in shale.

The performance of spiral groove dry gas seal under choked flow condition considering the real gas effect

2019 ◽  
Vol 234 (4) ◽  
pp. 554-566
Author(s):  
Hengjie Xu ◽  
Pengyun Song ◽  
Wenyuan Mao ◽  
Qiangguo Deng
Keyword(s):  
Carbon Dioxide ◽  
Flow Condition ◽  
Ideal Gas ◽  
Leakage Rate ◽  
Spiral Groove ◽  
Real Gas ◽  
Dry Gas Seal ◽  
Choked Flow ◽  
Real Gas Effect ◽  
Gas Effect

By taking carbon dioxide and hydrogen as lubricating gas, respectively, this paper presents an analysis on the pressure characteristics and temperature distribution of spiral groove dry gas seal which influenced by real gas effect under choked flow condition. Numerical results show that the deviation between real gas and ideal gas, which expressed by the deviation degree between compressibility factor Z and 1, is the main reason for real gas effect affecting sealing performance. Compared with ideal gas model, real gas effect raises exit pressure, opening force, leakage rate, Mach number in dam region, and temperature for carbon dioxide ( Z < 1), while it decreases those characteristics for hydrogen ( Z > 1) under the same operating conditions. In addition, choked flow effect increases opening force and reduces leakage rate and temperature-drop between entrance and exit of sealing clearance. Meanwhile, it may cause an unstable behavior for the seal.

Real Gas Effect on Unsteady Flow of Natural Gases in Shock Tubes

2011 ◽  
Vol 361-363 ◽  
pp. 603-606
Author(s):  
Yu Qiang Dai ◽  
Jiu Peng Zou ◽  
Che Zhu ◽  
Jin Tao Wu ◽  
Da Peng Hu
Keyword(s):  
Unsteady Flow ◽  
Flow Analysis ◽  
Shock Tubes ◽  
Wave Rotor ◽  
Real Gas ◽  
Natural Gases ◽  
Reflection And Refraction ◽  
Real Gas Effect ◽  
Unsteady Flow Analysis ◽  
Gas Effect

The unsteady flow behaviors in devices like gas wave machines, wave rotor refrigerators and so on are complex due to real gas effect at high operational pressure and low temperature. In this work, a detail computational model for unsteady flow analysis of real natural gases is established. The real effect on unsteady behaviors of natural gases in shock tubes have been studied extensively. Results show that the non-classical flow of the gases will not exist. The discipline of reflection and refraction of various gas waves or discontinuities remain unchanged for natural gases. Attention should be paid only to the deviations between perfect gas model and real gas model for gasdynamic waves.

1601 Numerical Simulation of Supersonic Nozzle Flow Considering Real Gas Effect

2011 ◽  
Vol 2011.24 (0) ◽  
pp. 513-514
Author(s):  
Tsubasa OHSHIMA ◽  
Hirotoshi YANAGI ◽  
Yasuhide OKAZAKI ◽  
Koji MORINISHI
Keyword(s):  
Numerical Simulation ◽  
Supersonic Nozzle ◽  
Nozzle Flow ◽  
Real Gas ◽  
Real Gas Effect ◽  
Gas Effect

Real gas effect in a laser heated thruster

AIAA Journal ◽  
1976 ◽  
Vol 14 (12) ◽  
pp. 1766-1768 ◽  
Author(s):  
Peter K. Wu
Keyword(s):  
Real Gas ◽  
Real Gas Effect ◽  
Laser Heated ◽  
Gas Effect

scholarly journals A Model for the Apparent Gas Permeability of Shale Matrix Organic Nanopore Considering Multiple Physical Phenomena

2022 ◽  
Vol 9 ◽  
Author(s):  
Wei Guo ◽  
Xiaowei Zhang ◽  
Rongze Yu ◽  
Lixia Kang ◽  
Jinliang Gao ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Pore Radius ◽  
Knudsen Diffusion ◽  
Stress Sensitivity ◽  
Confinement Effect ◽  
Apparent Permeability ◽  
Real Gas ◽  
Real Gas Effect ◽  
Physical Phenomena ◽  
Gas Effect

The flow of shale gas in nano scale pores is affected by multiple physical phenomena. At present, the influence of multiple physical phenomena on the transport mechanism of gas in nano-pores is not clear, and a unified mathematical model to describe these multiple physical phenomena is still not available. In this paper, an apparent permeability model was established, after comprehensively considering three gas flow mechanisms in shale matrix organic pores, including viscous slippage Flow, Knudsen diffusion and surface diffusion of adsorbed gas, and real gas effect and confinement effect, and at the same time considering the effects of matrix shrinkage, stress sensitivity, adsorption layer thinning, confinement effect and real gas effect on pore radius. The contribution of three flow mechanisms to apparent permeability under different pore pressure and pore size is analyzed. The effects of adsorption layer thinning, stress sensitivity, matrix shrinkage effect, real gas effect and confinement effect on apparent permeability were also systematically analyzed. The results show that the apparent permeability first decreases and then increases with the decrease of pore pressure. With the decrease of pore pressure, matrix shrinkage, Knudsen diffusion, slippage effect and surface diffusion effect increase gradually. These four effects will not only make up for the permeability loss caused by stress sensitivity and adsorption layer, but also significantly increase the permeability. With the decrease of pore radius, the contribution of slippage flow decreases, and the contributions of Knudsen diffusion and surface diffusion increase gradually. With the decrease of pore radius and the increase of pore pressure, the influence of real gas effect and confinement effect on permeability increases significantly. Considering real gas and confinement effect, the apparent permeability of pores with radius of 5 nm is increased by 13.2%, and the apparent permeability of pores with radius of 1 nm is increased by 61.3%. The apparent permeability model obtained in this paper can provide a theoretical basis for more accurate measurement of permeability of shale matrix and accurate evaluation of productivity of shale gas horizontal wells.

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