Systems and states

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
Equation Of State ◽  
Ideal Gas ◽  
State Function ◽  
System State ◽  
Molecular Interpretation ◽  
Definition Of ◽  
Key Terms ◽  
Boyle’S Law ◽  
The Ideal

An introduction to thermodynamics, its scope, applications and importance. Definition and exploration of key terms such as system, state, surroundings, boundary, intensive state function, extensive state function, and change in state. Definition of a key intensive state function, pressure. Introduction of the concept of an equation-of-state, with Boyle’s law as an example. Introduction to the ideal gas. Molecular interpretation of pressure.

scholarly journals On definition of the ideal gas

1910 ◽  
Vol 6 (3) ◽  
pp. 409
Author(s):  
E. Buckingham
Keyword(s):  
Ideal Gas ◽  
Definition Of ◽  
The Ideal

Simple Predictions for the Sonic Conditions in a Real Gas

1977 ◽  
Vol 99 (1) ◽  
pp. 217-225 ◽  
Author(s):  
P. A. Thompson ◽  
D. A. Sullivan
Keyword(s):  
Equation Of State ◽  
Closed Form ◽  
Thermodynamic Parameters ◽  
Ideal Gas ◽  
Accurate Prediction ◽  
Bernoulli Equation ◽  
Real Gas ◽  
Similarity Principle ◽  
Isentropic Flow ◽  
The Ideal

The steady isentropic flow of a fluid which satisfies an arbitrary equation of state is treated, with emphasis on the prediction of pressure, density, velocity, and massflow at the sonic state. The isentrope P(v) is described by a limited number of thermodynamic parameters, the most important ones being the soundspeed c and fundamental derivative Γ. Using this description, an application of the Bernoulli equation and appropriate thermodynamic relations yields simple closed-form predictions for the sonic state. These predictions are recognizable as generalizations of well-known ideal gas formulas, but are applicable to fluids very far removed from the ideal gas state, even including liquids. Comparisons in several cases for which precise independent solutions are available suggest that the methods found here are accurate. A derived similarity principle allows the accurate prediction of sonic properties from any single given sonic property.

Ideal gas processes – and two ideal gas case studies too

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
Case Studies ◽  
Constant Pressure ◽  
Ideal Gas ◽  
Heat Capacities ◽  
Carnot Cycle ◽  
State Function ◽  
Ideal Gases ◽  
First Case ◽  
The Ideal

This chapter brings together, and builds on, the results from previous chapters to provide a succinct, and comprehensive, summary of all key relationships relating to ideal gases, including the heat and work associated with isothermal, adiabatic, isochoric and isobaric changes, and the properties of an ideal gas’s heat capacities at constant volume and constant pressure. The chapter also has two ‘case studies’ which use the ideal gas equations in broader, and more real, contexts, so showing how the equations can be used to tackle, successfully, more extensive systems. The first ‘case study’ is the Carnot cycle, and so covers all the fundamentals required for the proof of the existence of entropy as a state function; the second ‘case study’ is the ‘thermodynamic pendulum’ – a system in which a piston in an enclosed cylinder oscillates to and fro like a pendulum under gravity, in both the absence, and presence, of friction.

Extremes in Dependences of Enthalpy and Entropy of Saturated Vapour on Temperature

1997 ◽  
Vol 62 (5) ◽  
pp. 679-695
Author(s):  
Josef P. Novák ◽  
Anatol Malijevský ◽  
Jaroslav Dědek ◽  
Jiří Oldřich
Keyword(s):  
Heat Capacity ◽  
Equation Of State ◽  
Ideal Gas ◽  
Corresponding States ◽  
Saturated Vapour ◽  
Enthalpy And Entropy ◽  
The Ideal

It was proved that the enthalpy of saturated vapour as a function of temperature has a maximum for all substances. The dependence of the entropy of saturated vapour on temperature can be monotonous, has a minimum and a maximum, or has only a maximum. The thermodynamic relations were derived for the existence of the extremes which enable their computation from the knowledge of dependence of the ideal-gas heat capacity on temperature and an equation of state. A method based on the theorem of corresponding states was proposed for estimating the extremes, and its results were compared with literature data. The agreement between the literature and estimated temperatures corresponding to the extremes is very good. The procedure proposed can serve for giving precision to the H-p and T-S diagrams commonly used in applied thermodynamics.

A comparative study of thermodynamic models to describe the VLE of the ternary electrolytic mixture H2O–NH3–CO2

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Licianne P. S. Rosa ◽  
Natan Cruz ◽  
Glória M. N. Costa ◽  
Karen V. Pontes
Keyword(s):  
Experimental Data ◽  
Liquid Phase ◽  
Equation Of State ◽  
Activity Coefficient ◽  
Vapor Phase ◽  
Large Scale ◽  
Optimization Problems ◽  
Ideal Gas ◽  
Simultaneous Optimization ◽  
The Ideal

Abstract This study aims to ascertain the influence of the activity coefficient model and equation of state for predicting the vapor–liquid equilibrium (VLE) of the multi-electrolytic system H2O–NH3–CO2. The non-idealities of the liquid phase are described by the eUNIQUAC and eNRTL models. The vapor phase is modeled with the Nakamura equation, which is compared with the ideal gas assumption. The models are validated with experimental data from literature on total pressure and ammonia partial pressure. Results show that the models UNIQUAC and NRTL without dissociation can only reproduce the experimental conditions in the absence of CO2. When the electrolytic term is considered, the eUNIQUAC model is able to reproduce the experimental data with greater accuracy than the eNRTL. The equation of state which describes the vapor phase plays no major role in the accuracy of the VLE prediction in the operational conditions evaluated here. Indeed, the accuracy relies on the activity coefficient, therefore the ideal gas equation can be considered if the non-idealities of the liquid phase are described by a well-tuned model. These findings could be useful for equipment design, flowsheet simulations and large-scale simultaneous optimization problems.

scholarly journals Quantitative Mereology: An Essay to Derive Physics Laws from a Philosophical Concept

2019 ◽  
Author(s):  
Georg J. Schmitz
Keyword(s):  
Algebraic Equation ◽  
Basic Equation ◽  
Energy Levels ◽  
Lorentz Factor ◽  
Ideal Gas ◽  
Hypercomplex Numbers ◽  
Philosophical Concept ◽  
Definition Of ◽  
The Universe ◽  
The Ideal

Mereology stands for the philosophical concept of parthood and is based on a sound set of fundamental axioms and relations. One of these axioms relates to the existence of a universe as a thing having part all other things. The present article formulates this logical expression first as an algebraic inequality and eventually as an algebraic equation reading in words: The universe equals the sum of all things. “All things” here are quantified by a “number of things”. Eventually this algebraic equation is normalized leading to an expression The whole equals the sum of all fractions. This introduces “1” or “100%” as a quantitative – numerical - value describing the “whole”. The resulting “basic equation” can then be subjected to a number of algebraic operations. Especially squaring this equation leads to correlation terms between the things implying that the whole is more than just the sum of its parts. Multiplying the basic equation (or its square) by a scalar allows for the derivation of physics equations like the entropy equation, the ideal gas equation, an equation for the Lorentz-Factor, conservation laws for mass and energy, the energy-mass equivalence, the Boltzmann statistics, and the energy levels in a Hydrogen atom. It further allows deriving a “contrast equation” which may form the basis for the definition of a length and a time scale. Multiplying the basic equation with vectors, pseudovectors, pseudoscalars and eventually hypercomplex numbers opens up the realm of possibilities to generate many further equations.

scholarly journals CONCERNING THE EQUATION OF STATE FOR A PARTIALLY IONIZED SYSTEM

2009 ◽  
Vol 23 (20n21) ◽  
pp. 3968-3978
Author(s):  
GEORGE A. BAKER
Keyword(s):  
Equation Of State ◽  
Ideal Gas ◽  
Thermodynamic Quantities ◽  
Low Density ◽  
Cellular Model ◽  
Density Region ◽  
Cellular Models ◽  
Maxwell Construction ◽  
Actual Region ◽  
The Ideal

I will discuss the expansion of various thermodynamic quantities about the ideal gas in powers of the electric charge, and I will discuss some cellular models. The first type of cellular model is appropriate for hydrogen. The second type is for Z > 1. It has the independent electron approximation within the atoms. These models are cross compared and minimal regions of validity are determined. The actual region of validity is expected to be larger. In the cellular models, the phase boundaries for liquid-gas transitions are found. For the second type of cellular model, in the part of the low-temperature, low-density region where there is not much expectation of validity of these methods, a non-thermodynamic region is found. I have devised a construction, similar in spirit to the Maxwell construction, to bridge this region so as to leave a thermodynamically valid equation of state. The non-thermodynamic region does not occur in hydrogen and it seems to be due to the inadequacy of the aforementioned approximation in that region.

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