Loci of maxima and minima of thermodynamic functions of a simple fluid

1976 ◽  
Vol 54 (12) ◽  
pp. 1282-1291 ◽  
Author(s):  
John Stephenson
Keyword(s):  
Specific Heat ◽  
Thermodynamic Functions ◽  
Speed Of Sound ◽  
Isothermal Compressibility ◽  
Constant Pressure ◽  
Van Der Waals ◽  
Experimental Results ◽  
Van Der Waals Equation ◽  
Simple Fluid ◽  
Fluid Argon

Some elementary properties of loci of extrema of thermodynamic functions are established and discussed in connection with maxima and minima of the constant volume specific heat, CV, the isothermal compressibility, χT, and the constant pressure specific heat, CP, along isotherms, and the extremum properties of the isobaric coefficient of expansion, αP, along isobars. Experimental results for fluid argon are used to construct the required loci of extrema. Van der Waals' equation is applied to obtain loci of extrema for χT, CP, and αP, for the speed of sound W, and for related inflexion loci.

Thermodynamic Functions at Isobaric Process of van der Waals Gases

2000 ◽  
Vol 55 (11-12) ◽  
pp. 851-855
Author(s):  
Akira Matsumoto
Keyword(s):  
Heat Capacity ◽  
Free Energy ◽  
Critical Point ◽  
Thermodynamic Functions ◽  
Isothermal Compressibility ◽  
Van Der Waals ◽  
Thermal Expansivity ◽  
Van Der Waals Equation ◽  
Reduced Temperature ◽  
Isobaric Process

Abstract The thermodynamic functions for the van der Waals equation are investigated at isobaric process. The Gibbs free energy is expressed as the sum of the Helmholtz free energy and PV, and the volume in this case is described as the implicit function of the cubic equation for V in the van der Waals equation. Furthermore, the Gibbs free energy is given as a function of the reduced temperature, pressure and volume, introducing a reduced equation of state. Volume, enthalpy, entropy, heat capacity, thermal expansivity, and isothermal compressibility are given as functions of the reduced temperature, pressure and volume, respectively. Some thermodynamic quantities are calculated numerically and drawn graphically. The heat capacity, thermal expansivity, and isothermal compressibility diverge to infinity at the critical point. This suggests that a second-order phase transition may occur at the critical point.

A Study of Fluid Argon via the Constant Volume Specific Heat, the Isothermal Compressibility, and the Speed of Sound and their Extremum Properties along Isotherms

1975 ◽  
Vol 53 (14) ◽  
pp. 1367-1384 ◽  
Author(s):  
John Stephenson
Keyword(s):  
Equation Of State ◽  
Specific Heat ◽  
Speed Of Sound ◽  
Isothermal Compressibility ◽  
Constant Volume ◽  
Liquid Region ◽  
Fluid Argon ◽  
Unified Description ◽  
Dense Liquid ◽  
Sound Data

The properties of fluid argon are investigated via the maxima and minima along isotherms of selected thermodynamic functions, the isothermal compressibility, χT, the constant volume specific heat, CV, and the speed of sound, W. Calculations are based on an equation of state due to Gosman, McCarty, and Hust and on speed of sound data compiled by Thoen, Vangeel, and Van Dael. The calculation of CV in the dense liquid region, from the equation of state and from the speed of sound, is discussed in detail. Also, the linear dependence of W on the density in the liquid region is reconciled with the behaviour of W at temperatures above critical to obtain a unified description of the variation of W along isotherms.

FALSIFICATIONS OF POISSON ADIABATE, HUGONIO ADIABATE, LAPLACE SOUND SPEEDS. MODERNIZATION OF FOUNDATIONS OF THERMODYNAMICS

2020 ◽  
Vol 5 (333) ◽  
pp. 58-67
Author(s):  
K.B. Jakupov ◽  
Keyword(s):  
Shock Wave ◽  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Speed Of Sound ◽  
Constant Pressure ◽  
Energy Balance Equation ◽  
Ideal Gas ◽  
Constant Volume ◽  
Capacity Coefficient

The inequality of the universal gas constant of the difference in the heat capacity of a gas at constant pressure with the heat capacity of a gas at a constant volume is proved. The falsifications of using the heat capacity of a gas at constant pressure, false enthalpy, Poisson adiabat, Laplace sound speed, Hugoniot adiabat, based on the use of the false equality of the universal gas constant difference in the heat capacity of a gas at constant pressure with the heat capacity of a gas at a constant volume, have been established. The dependence of pressure on temperature in an adiabatic gas with heat capacity at constant volume has been established. On the basis of the heat capacity of a gas at a constant volume, new formulas are derived: the adiabats of an ideal gas, the speed of sound, and the adiabats on a shock wave. The variability of pressure in the field of gravity is proved and it is indicated that the use of the specific coefficient of ideal gas at constant pressure in gas-dynamic formulas is pointless. It is shown that the false “basic formula of thermodynamics” implies the falseness of the equation with the specific heat capacity at constant pressure. New formulas are given for the adiabat of an ideal gas, adiabat on a shock wave, and the speed of sound, which, in principle, do not contain the coefficient of the specific heat capacity of a gas at constant pressure. It is shown that the well-known equation of heat conductivity with the gas heat capacity coefficient at constant pressure contradicts the basic energy balance equation with the gas heat capacity coefficient at constant volume.

scholarly journals (P,ρ,T) properties of 1-octyl-3-methylimidazolium tetrafluoroborate

2018 ◽  
Vol 83 (1) ◽  
pp. 61-73 ◽  
Author(s):  
Javid Safarov ◽  
Aygul Namazova ◽  
Astan Shahverdiyev ◽  
Egon Hassel
Keyword(s):  
Equation Of State ◽  
Speed Of Sound ◽  
Isothermal Compressibility ◽  
Constant Pressure ◽  
Pressure Coefficient ◽  
Heat Capacities ◽  
Thermal Pressure ◽  
Average Percent Deviation ◽  
Wide Range ◽  
Isentropic Exponent

(p,?,T) data of 1-octyl-3-methylimidazolium tetrafluoroborate [OMIM][BF4] over a wide range of temperatures, from 278.15 to 413.15 K, and pressures, p, up to 140 MPa are reported with an estimated ?0.01?0.08 % experimental relative average percent deviation (APD) in the density. The measurements were performed using an Anton Paar DMA HPM vibration tube densimeter. (p,?,T) Data for [OMIM][BF4] was fitted and the parameters of the applied equation were determined as a function of pressure and temperature. After a thorough analysis of literature values and validity of the used equation of state, various thermophysical properties, such as isothermal compressibility, isobaric thermal expansibility, differences in isobaric and isochoric heat capacities, thermal pressure coefficient, internal pressure, heat capacities at constant pressure and volume, speed of sound and isentropic exponent at temperatures in the range 278.15?413.15 K and pressures p up to 140 MPa were calculated.

Chapman-Jouguet Combustion Waves in Van Der Waals and Noble-Abel Gases

2018 ◽  
pp. 51-78
Author(s):  
Fernando S. Costa ◽  
César A. Q. Gonzáles
Keyword(s):  
Equation Of State ◽  
Van Der Waals ◽  
Experimental Results ◽  
Intermolecular Force ◽  
Jump Conditions ◽  
Combustion Waves ◽  
Van Der Waals Equation ◽  
One Dimensional ◽  
Hugoniot Curves ◽  
Theoretical Results

This chapter adopts the Chapman-Jouguet approach to derive jump conditions across combustion waves propagating in Van der Waals and Noble-Abel gases. The steady one-dimensional balance equations of mass, momentum and energy, assuming different properties of reactants and products, are applied to obtain the main properties of combustion waves, including velocities, Mach numbers, pressures and temperatures, in terms of the covolumes and intermolecular force parameters. In general, the effects of covolumes are more significant than the effects of the intermolecular attraction forces on Hugoniot curves and on properties of combustion waves. However, theoretical results using the Van der Waals equation of state matched more closely the experimental results for detonations of mixtures of propane and diluted air at high initial pressures.

The thermodynamic properties of fluid helium

1960 ◽  
Vol 252 (1013) ◽  
pp. 357-395 ◽  
Keyword(s):  
Thermodynamic Properties ◽  
Specific Heat ◽  
Internal Energy ◽  
Thermodynamic Functions ◽  
Single Phase ◽  
Constant Pressure ◽  
Pressure Coefficient ◽  
Differential Method ◽  
Constant Volume ◽  
Gibbs Function

Measurements have been made from which all the thermodynamic properties of fluid helium can be calculated in the temperature range from 3 to 20 °K and up to 100 atm pressure. The quantities measured were: (i) the specific heat at constant volume as a function of temperature and density, (ii) the pressure coefficient at constant volume ( also as a function of temperature and density, (iii) the pressure as a function of temperature at constant volume (isochores) for a range of densities. A particular feature of the experiments is that the important derivative ( )v, from which the changes of entropy and internal energy with volume at constant temperature are calculated, was measured directly by a differential method. Starting from the known entropy and internal energy of the liquid near its normal boiling point, these two quantities were calculated for all single phase states within the experimental range. From these, and using the equation of state data, the enthalpy, free energy, Gibbs function, and the specific heat at constant pressure have been deduced. The thermodynamic functions, together with some useful state properties, are tabulated as functions of temperature and either volume or pressure as relevant. The choice of the measured quantities was such that all the thermodynamic functions except the specific heat at constant pressure were obtained by integration of the experimental data; these functions therefore have the same accuracy as the measured quantities, about 1 %.

On the Constant Pressure Specific Heat CP of a Simple Fluid

1983 ◽  
Vol 13 (2) ◽  
pp. 81-90
Author(s):  
John Stephenson ◽  
Ken McGreer ◽  
Gordon Macleod
Keyword(s):  
Specific Heat ◽  
Constant Pressure ◽  
Simple Fluid

Thermodynamic properties of crystalline KCl

1989 ◽  
Vol 67 (7) ◽  
pp. 664-668 ◽  
Author(s):  
T. H. Kwon
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Thermodynamic Properties ◽  
Specific Heat ◽  
Thermal Expansion Coefficient ◽  
Thermodynamic Functions ◽  
Linear Thermal Expansion Coefficient ◽  
Constant Pressure ◽  
Linear Thermal Expansion ◽  
Adiabatic Compressibility

Thermodynamic functions of crystalline KCl have been evaluated using a localized model characterized by a pseudopotential and direct Brillouin zone sums. Numerical results are compared with available experimental data for adiabatic compressibility, the linear thermal expansion coefficient, specific heat at constant volume, and specific heat at constant pressure. Calculated results show excellent agreement with experimentally observed data.

Experimental Study on the Specific Heat Capacity Measurement of Water-Based Al2O3-Cu Hybrid Nanofluid by using Differential Thermal Analysis Method

2019 ◽  
Vol 15 ◽  
Author(s):  
Andaç Batur Çolak ◽  
Oğuzhan Yıldız ◽  
Mustafa Bayrak ◽  
Ali Celen ◽  
Ahmet Selim Dalkılıç ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Thermophysical Properties ◽  
Volume Concentration ◽  
Pure Water ◽  
Heat Capacity Measurement ◽  
Experimental Results ◽  
Hybrid Nanofluid ◽  
Capacity Measurement

Background: Researchers working in the field of nanofluid have done many studies on the thermophysical properties of nanofluids. Among these studies, the number of studies on specific heat are rather limited. In the study of the heat transfer performance of nanofluids, it is necessary to increase the number of specific heat studies, whose subject is one of the important thermophysical properties. Objective: The authors aimed to measure the specific heat values of Al2O3/water, Cu/water nanofluids and Al2O3-Cu/water hybrid nanofluids using the DTA method, and compare the results with those frequently used in the literature. In addition, this study focuses on the effect of temperature and volume concentration on specific heat. Method: The two-step method was used in the preparation of nanofluids. The pure water selected as the base fluid was mixed with the Al2O3 and Cu nanoparticles and Arabic Gum as the surfactant, firstly mixed in the magnetic stirrer for half an hour. It was then homogenized for 6 hours in the ultrasonic homogenizer. Results: After the experiments, the specific heat of nanofluids and hybrid nanofluid were compared and the temperature and volume concentration of specific heat were investigated. Then, the experimental results obtained for all three fluids were compared with the two frequently used correlations in the literature. Conclusion: Specific heat capacity increased with increasing temperature, and decreased with increasing volume concentration for three tested nanofluids. Cu/water has the lowest specific heat capacity among all tested fluids. Experimental specific heat capacity measurement results are compared by using the models developed by Pak and Cho and Xuan and Roetzel. According to experimental results, these correlations can predict experimental results within the range of ±1%.

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