New method for equation-of-state calculations: Linear combinations of basis potentials

1982 ◽  
Vol 26 (6) ◽  
pp. 3633-3645 ◽  
Author(s):  
Yaakov Rosenfeld
Keyword(s):  
Equation Of State ◽  
New Method ◽  
Linear Combinations

Identification of Simultaneous Equation Model in Econometrics

2011 ◽  
Vol 58-60 ◽  
pp. 1944-1947
Author(s):  
Hou Xing Tang
Keyword(s):  
Econometric Model ◽  
Simultaneous Equation ◽  
Equation Model ◽  
New Method ◽  
Simultaneous Equation Model ◽  
Linear Combinations ◽  
Definition Of ◽  
Simultaneous Equation Models

Identification is an important topic on simultaneous equation econometric model. It determines that whether the coefficients of the simultaneous equation models can be estimated. From the definition of identification perspective, this article will provide a new method about identification based on the relation between identified equations and the linear combinations of all equations.

scholarly journals A New Method to Calculate the Pure Component Parameters of Any Two-Parameter Equation of State

2011 ◽  
Vol 2011 ◽  
pp. 1-6
Author(s):  
Isam H. Aljundi
Keyword(s):  
Equation Of State ◽  
Equations Of State ◽  
Saturated Vapor ◽  
Pure Component ◽  
New Method ◽  
Average Deviation ◽  
Cubic Equation ◽  
Parameter Equation ◽  
Temperature Dependences ◽  
Two Parameter

Reliable equations of state are very important in the design of refrigeration cycles, since thermodynamic properties can be calculated by simple differentiation. In this paper, a new method to calculate the parameters of any two-parameter equation of state is presented. The method is based on the use of Clapeyron equation and the experimental PVT data. This method was tested on a newly developed cubic equation of state and proved to be simple and fast. Results showed orders of magnitude enhancement in prediction of the saturated vapor pressure even near the critical region. The Percent Absolute Average Deviation (%AAD) was always less than 0.1 in the studied cases. It also showed that the parameters calculated using the original equation deviate strongly from the “experimental” values as the temperature decreases below the critical point. This method can be used to redefine the temperature dependences of these parameters and develop new mixing rules for the mixtures.

scholarly journals Optimization of the quintic equation of the state based model for the calculations of different thermodynamic properties

2008 ◽  
Vol 10 (1) ◽  
pp. 6-10 ◽  
Author(s):  
Antoni Kozioł ◽  
Radosław Wiśniewski
Keyword(s):  
Experimental Data ◽  
Equation Of State ◽  
Thermodynamic Properties ◽  
Saturation Pressure ◽  
The State ◽  
New Method ◽  
Original Form ◽  
Liquid Density ◽  
Temperature Dependent ◽  
Quintic Equation

Optimization of the quintic equation of the state based model for the calculations of different thermodynamic properties Different thermodynamic properties (the vapour density, the liquid density and the saturation pressure) were calculated by the model based on the Nakamura-Breedveld-Prausnitz equation of state (NBP EOS). Since the original form of the NBP EOS often generates inaccurate results for liquids, it was modified to describe this phase better. The calculations were realized in the subcritical region. So far, the temperature-dependent NBP EOS parameters have been obtained by special correlations. Their constants were fitted to a lot of experimental data. In this paper the equation of state temperature-dependent parameters were obtained by a new method which was based at piecewise cubic Hermite interpolating polynomials (PCHIPs). In the proposed method some experimental data (called the key ones) were used, thus reducing the experimental effort. Seven substances were chosen for the test calculations. Each of them is common in industry. The calculation results were compared with the experimental data. The new method has made an accurate description of vapour-liquid equilibrium for the considered pure substances over a wide temperature range possible.

scholarly journals A Two-Step Modified Explicit Hybrid Method with Step-Size-Dependent Parameters for Oscillatory Problems

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Faieza Samat ◽  
Eddie Shahril Ismail
Keyword(s):  
Differential Equations ◽  
Hybrid Method ◽  
Absolute Stability ◽  
Numerical Results ◽  
Sixth Order ◽  
New Method ◽  
Step Size ◽  
Linear Combinations ◽  
Size Dependent ◽  
Modified Formula

A new two-step modified explicit hybrid method with parameters depending on the step-size is constructed. This method is derived using the coefficients from a sixth-order explicit hybrid method with extended interval of absolute stability and then imposed each stage of the modified formula to exactly integrate the differential equations with solutions that can be expressed as linear combinations of sinwx and coswx, where w is the known frequency. Numerical results show the advantage of the new method for solving oscillatory problems.

Sign in / Sign up

Export Citation Format

Share Document