scholarly journals The effect of the spinodal curve condition on J T inversion curves for van der Waals real gas

2015 ◽  
Vol 10 (19) ◽  
pp. 610-614 ◽  
Author(s):  
Venetis J
Keyword(s):  
Van Der Waals ◽  
Real Gas ◽  
Spinodal Curve

scholarly journals Nonlinear Processes in Safety Systems for Substances with Parameters Close to a Critical State

2021 ◽  
Vol 17 (1) ◽  
pp. 119-138
Author(s):  
M. R. Koroleva ◽  
◽  
O. V. Mishchenkova ◽  
V. A. Tenenev ◽  
T. Raeder ◽  
...  
Keyword(s):  
Equation Of State ◽  
Critical State ◽  
Stokes Equations ◽  
Safety Valve ◽  
Van Der Waals ◽  
Local Approximation ◽  
Critical Conditions ◽  
Nonlinear Processes ◽  
Real Gas ◽  
Van Der Waals Equation

The paper presents a modification of the digital method by S. K. Godunov for calculating real gas flows under conditions close to a critical state. The method is generalized to the case of the Van der Waals equation of state using the local approximation algorithm. Test calculations of flows in a shock tube have shown the validity of this approach for the mathematical description of gas-dynamic processes in real gases with shock waves and contact discontinuity both in areas with classical and nonclassical behavior patterns. The modified digital scheme by Godunov with local approximation of the Van der Waals equation by a two-term equation of state was used for simulating a spatial flow of real gas based on Navier – Stokes equations in the area of a complex shape, which is characteristic of the internal space of a safety valve. We have demonstrated that, under near-critical conditions, areas of nonclassical gas behavior may appear, which affects the nature of flows. We have studied nonlinear processes in a safety valve arising from the movement of the shut-off element, which are also determined by the device design features and the gas flow conditions.

Analytical treatment of the critical properties of a generalized van der Waals equation

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Magdy E Amin
Keyword(s):  
Van Der Waals ◽  
Critical Properties ◽  
Analytical Treatment ◽  
Real Gas ◽  
Cubic Equation ◽  
Isobaric Expansion ◽  
Isobaric Expansion Coefficient ◽  
General Relations ◽  
Two Parameters ◽  
Two Parameter

Abstract The two-parameter van der Waals (vdW) equation of state is generalized, by adding another two parameters to the attractive term. General relations between thermodynamic functions of the generalized vdW equation and the hard sphere gas are derived. The cubic equation of the generalized vdW is solved and the critical points (P c , V c , T c ) are obtained for general k. The critical properties of the vdW real gas such as the isothermal compressibility K T , the isobaric expansion coefficient α and the isobaric heat capacity C P are calculated exactly. The temperature dependence of K T , α and C P is investigated close to the critical point on the critical isobar path P r = 1(P = P c ). Numerical calculations for K T and C P are presented above and below P r .

An Explanation of the pVm-p Curve of Real Gas by van der Waals Gas Equation

Daxue Huaxue ◽  
2016 ◽  
Vol 31 (3) ◽  
pp. 73-77
Author(s):  
Qi CUI ◽  
◽  
Guo-Liang LI ◽  
Ying-Hui ZHANG
Keyword(s):  
Van Der Waals ◽  
Van Der Waals Gas ◽  
Real Gas

Model and Simulaiton of Air Spring Stiffness Characteristics Based on van der Waals Equation

2013 ◽  
Vol 779-780 ◽  
pp. 380-383
Author(s):  
Li Qin Sun ◽  
Zhong Xing Li ◽  
Xu Feng Shen ◽  
Hua Wei Zhao
Keyword(s):  
Van Der Waals ◽  
Ideal Gas ◽  
Factor H ◽  
Spring Stiffness ◽  
Air Spring ◽  
Real Gas ◽  
Van Der Waals Equation ◽  
Working Temperature ◽  
Stiffness Model ◽  
Stiffness Characteristics

Air spring gas is generally regarded as an ideal gas in analysis , but this is not consistent with the actual work . Considerring influence of non-ideal gas to air spring stiffness ,and based on van der Waals equation which is closed to the real gas equation, stiffness characteristics model of air spring and air spring with auxiliary chamber are re-derived and established. Influence of non ideal gas correction factor H to air spring stiffness is analysed within the range of pressure 0.2MPa to 5 MPa and working temperature -50 °C to 50°C,and results show that , there are big errors in air spring stiffness model in the conditon of low temperature and high pressure based on ideal gas equation, and range of application of the stiffness model is expanded when H is introduced and amended.

scholarly journals The Equation of State of Biogas

2017 ◽  
Vol 65 (2) ◽  
pp. 537-543
Author(s):  
Petr Trávníček ◽  
Tomáš Vítěz ◽  
Tomáš Koutný
Keyword(s):  
Equation Of State ◽  
Theoretical Approach ◽  
Van Der Waals ◽  
Compressibility Factor ◽  
Calculated Data ◽  
State Behavior ◽  
Real Gas ◽  
Van Der Waals Equation ◽  
Geometric Average ◽  
Pure Substances

The presented work deals with a state behavior of real gas, biogas. Theoretical approach was utilized for processing of this work. Compressibility factor was calculated with help of two equation of state – Van der Waals equation and Redlich‑Kwong equation. Constants a and b of both equations were calculated using geometric average of the constants of pure substances. On the basis of calculated data charts showing the dependence of compressibility factor and the pressure were created. These charts were created for temperatures 20 °C and 40 °C. Statistical analyses of data were carried out. The results showed that compressibility factor reached value from 0.997 to 0.97 (20 °C) and from 0.997 to 0.974 (40 °C) in the case Van der Waals equation and in the range of pressure from 100 kPa to 1000 kPa. In the case of Redlich‑Kwong equation these values were from 0.997 to 0.967 (20 °C) and from 0.997 to 0.974 (40 °C) in the same range of pressures.

scholarly journals Dynamical analysis of an n−H−T cosmological quintessence real gas model with a general equation of state

2018 ◽  
Vol 33 (03) ◽  
pp. 1850025 ◽  
Author(s):  
Rossen I. Ivanov ◽  
Emil M. Prodanov
Keyword(s):  
Equation Of State ◽  
General Equation ◽  
Van Der Waals ◽  
Three Dimensional ◽  
Dynamical Analysis ◽  
Real Gas ◽  
Cyclic Universe ◽  
Closed Orbits ◽  
Stable Periodic ◽  
Dimensional Dynamical System

The cosmological dynamics of a quintessence model based on real gas with general equation of state is presented within the framework of a three-dimensional dynamical system describing the time evolution of the number density, the Hubble parameter and the temperature. Two global first integrals are found and examples for gas with virial expansion and van der Waals gas are presented. The van der Waals system is completely integrable. In addition to the unbounded trajectories, stemming from the presence of the conserved quantities, stable periodic solutions (closed orbits) also exist under certain conditions and these represent models of a cyclic Universe. The cyclic solutions exhibit regions characterized by inflation and deflation, while the open trajectories are characterized by inflation in a “fly-by” near an unstable critical point.

scholarly journals An Efficient Analytical Solution of Blast Wave Problem in Real Gas Flow under the Influence of Dust-Laden Particles

2020 ◽  
Vol 9 (3) ◽  
pp. 2490-2494
Keyword(s):  
Hyperbolic System ◽  
Gas Flow ◽  
Van Der Waals ◽  
Unsteady Motion ◽  
Ideal Gas ◽  
Blast Waves ◽  
Dust Particles ◽  
Van Der Waals Gas ◽  
Real Gas ◽  
Flow Parameters

In the present paper, we investigated the problem of the propagation of blast waves governed by a nonhomogeneous quasilinear hyperbolic system of partial differential equations (PDEs), describing one-dimensional unsteady motion with generalized geometries in a real gas flow (van der Waals gas) in which the influence of the dust particles is significant. An efficient analytical approach has been used to the governing hyperbolic system with respect to the Rankine-Hugoniot (RH) conditions to obtain an exact solution in terms of flow parameters density, velocity and the pressure, which exhibits space-time dependence. Further, an analytical expression for the total energy influenced by real gas effects (consisting of non-ideal gas and small solid dust-laden particles) is derived. The results obtained significantly explore the effect of dust-laden particles on the propagation of blast waves in a van der Waals gas.

Sign in / Sign up

Export Citation Format

Share Document