scholarly journals Saturated-liquid heat capacity: New polynomial models and review of the literature experimental data

2003 ◽  
Vol 68 (6) ◽  
pp. 479-495 ◽  
Author(s):  
Jovan Jovanovic ◽  
Dusan Grozdanic
Keyword(s):  
Experimental Data ◽  
Heat Capacity ◽  
Heat Capacities ◽  
Review Of The Literature ◽  
Saturated Liquid ◽  
Correlation Models ◽  
Polynomial Models ◽  
Liquid Heat

In this paper a review of selected literature experimental data for saturated-liquid heat capacities was presented. Two-, three- and four-parameter polynomial correlation models are tested on those data. Obtained results lead to the conclusion that correlation quality depends on the number of parameters, and slightly on the type of models. The best two three- and four-parameter models were proposed.

scholarly journals Saturated-liquid heat capacity of organic compounds: New empirical correlation model

2004 ◽  
Vol 69 (3) ◽  
pp. 233-237 ◽  
Author(s):  
Jovan Jovanovic ◽  
Dusan Grozdanic
Keyword(s):  
Heat Capacity ◽  
Critical Point ◽  
Organic Compounds ◽  
Correlation Model ◽  
Saturated Liquid ◽  
Experimental Heat ◽  
Capacity Model ◽  
Polynomial Models ◽  
Liquid Heat ◽  
Capacity Data

A new saturated-liquid heat capacity model is recommended. This model is tested and compared with the known polynomial and quasi-polynomial models on 39 sets with 1453 experimental heat capacity data. The obtained results indicate that the new model is better then the existing models, especially near the critical point.

scholarly journals Calculation of the Isobaric Heat Capacities of the Liquid and Solid Phase of Organic Compounds at 298.15K by Means of the Group-Additivity Method

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1147
Author(s):  
Rudolf Naef
Keyword(s):  
Experimental Data ◽  
Heat Capacity ◽  
Goodness Of Fit ◽  
Cross Validation ◽  
Solid Phase ◽  
Linear Equations ◽  
Heat Capacities ◽  
Molecular Volume ◽  
Complementary Method ◽  
Standard Deviations

The calculation of the isobaric heat capacities of the liquid and solid phase of molecules at 298.15 K is presented, applying a universal computer algorithm based on the atom-groups additivity method, using refined atom groups. The atom groups are defined as the molecules’ constituting atoms and their immediate neighbourhood. In addition, the hydroxy group of alcohols are further subdivided to take account of the different intermolecular interactions of primary, secondary, and tertiary alcohols. The evaluation of the groups’ contributions has been carried out by solving a matrix of simultaneous linear equations by means of the iterative Gauss–Seidel balancing calculus using experimental data from literature. Plausibility has been tested immediately after each fitting calculation using a 10-fold cross-validation procedure. For the heat capacity of liquids, the respective goodness of fit of the direct (r2) and the cross-validation calculations (q2) of 0.998 and 0.9975, and the respective standard deviations of 8.24 and 9.19 J/mol/K, together with a mean absolute percentage deviation (MAPD) of 2.66%, based on the experimental data of 1111 compounds, proves the excellent predictive applicability of the present method. The statistical values for the heat capacity of solids are only slightly inferior: for r2 and q2, the respective values are 0.9915 and 0.9874, the respective standard deviations are 12.21 and 14.23 J/mol/K, and the MAPD is 4.74%, based on 734 solids. The predicted heat capacities for a series of liquid and solid compounds have been directly compared to those received by a complementary method based on the "true" molecular volume and their deviations have been elucidated.

scholarly journals A New Four-Parameter Cubic Equation of State for Predicting Fluid Phase Behavior

2019 ◽  
Author(s):  
zhiren he
Keyword(s):  
Heat Capacity ◽  
Equation Of State ◽  
Vapor Pressure ◽  
Saturated Vapor ◽  
Liquid Density ◽  
Saturated Liquid ◽  
Cubic Equation ◽  
Liquid Heat ◽  
Entropy Of Vaporization ◽  
Saturated Liquid Density

<p>A new four-parameter cubic equation of state (EoS) is generated by incorporating the critical compressibility factor (Z<sub>c</sub>) apart from the critical pressure (P<sub>c</sub>) and temperature (T<sub>c</sub>). One free parameter in the denominator of the attractive term and two parameters in the alpha function are adjusted using the experimental data of saturated liquid density, vapor pressure, and isobaric liquid heat capacity of 48 components including hydrocarbons and non-hydrocarbons. Applying this equation of state, saturated liquid density, saturated vapor density, and vapor pressure of pure components are accurately reproduced compared with experimental values. Furthermore, the predicted properties including derivatives of alpha function, such as enthalpy of vaporization, entropy of vaporization and isobaric heat capacity of liquid, also have decent accuracy. The global average absolute relative deviation (AAD) of saturated liquid density, saturated vapor density, saturated vapor pressure, enthalpy of vaporization, entropy of vaporization, and isobaric heat capacity of liquid in a wide reduced temperature (Tr) range of subcritical region reproduced by this work are 4.33%, 4.18%, 3.19%, 2.26%, 2.27%, and 5.82%, respectively. Substantial improvement has been achieved for the isobaric liquid heat capacity calculation.</p>

The heat capacities of certain liquids

1957 ◽  
Vol 239 (1217) ◽  
pp. 230-246 ◽  
Keyword(s):  
Heat Capacity ◽  
Carbon Tetrachloride ◽  
Carbon Disulphide ◽  
Heat Capacities ◽  
Constant Volume ◽  
Pressure Data ◽  
Different Temperatures ◽  
Structural Contribution ◽  
Liquid Heat ◽  
Total Heat Capacity

The heat capacities and adiabatic compressibilities of carbon tetrachloride, chloroform, methylene dibromide and m ethyl iodide have been measured between about — 30 and 30° C. The heat capacities at constant volume have been derived, and it is emphasized th a t these quantities apply to particular volumes existing at different temperatures. An isotherm for liquids, based on high-pressure data, has been used to obtain an expression for the effect of change of volume on the heat capacity at constant volume. This relation has been applied to mercury, carbon disulphide, carbon tetrachloride, chloroform and water. Satisfactory agreement has been obtained with the results found in other ways by Bridgman (1911, 1912) on mercury and water and by Gibson & Loeffler (1941) on carbon tetrachloride and water. From the results found in this work on the resolution of the various energy contributions to the liquid heat capacities of polyatomic molecules other than water, it is concluded that the concept of molecular rotation about a preferred axis can explain most of the facts established. There remains, however, a structural contribution to the total heat capacity which is approximately R cal mole -1 deg. -1 .

scholarly journals Mean-field parameters of some PrxTb(1-x)Al2 compounds found via searching for the best magnetic heat capacity fitting

2021 ◽  
Vol 2090 (1) ◽  
pp. 012081
Author(s):  
J. C. G. Tedesco ◽  
V.J. Monteiro ◽  
A. M. G. Carvalho ◽  
L.P. Cardoso ◽  
A. A. Coelho
Keyword(s):  
Experimental Data ◽  
Heat Capacity ◽  
Magnetocaloric Effect ◽  
Mean Field ◽  
Heat Capacities ◽  
Field Approach ◽  
Physical Limitations ◽  
The Mean ◽  
Good Agreement

Abstract Simulations of the magnetic heat capacity of some (Pr, Tb)Al2 compounds were performed using the mean-field approach. The developed routine aims to optimize the set of mean-field parameters. The proposed algorithm calculates the sum of squared differences between the experimental points and the simulated curve and then changes the parameters in order to minimize this sum. This searching leads to consistent values that can reproduce the experimental data. The parameters found in this work reproduced the heat capacities curves of the PrxTb(1−x)Al2 compounds, x=0.25, x=0.50 and x=0.75, with good agreement. The physical limitations of the mean-field approach do not preclude analysing the results. These parameters are important because they can help to understand and calculate the magnetocaloric effect these materials can present.

scholarly journals Calorimetric Research into the Heat Capacity of Novel Nano-Sized Cobalt(Nickelite)-Cuprate-Manganites of LaBaMeIICuMnO6 (MeII = Co, Ni) and their Thermodynamic Properties

2020 ◽  
Vol 22 (1) ◽  
pp. 27
Author(s):  
B.K. Kassenov ◽  
Sh.B. Kassenova ◽  
Zh.I. Sagintaeva ◽  
E.E. Kuanyshbekov ◽  
M.O. Turtubaeva
Keyword(s):  
Experimental Data ◽  
Heat Capacity ◽  
Calculated Data ◽  
Heat Capacities ◽  
Fundamental Constants ◽  
Debye Theory ◽  
Standard Heat ◽  
Standard Heat Capacity ◽  
Dynamic Calorimetry ◽  
Temperature Dependences

The isobaric heat capacities of novel nano-sized cobalt-cuprate-manganite of lanthanum and barium LaBaCoCuMnO6 and nickel-cuprate-manganite of lanthanum and barium LaBaNiCuMnO6 were investigated by dynamic calorimetry over the temperature range of 298.15‒673 K. It is found that a λ-shaped effect is observed on the curve of the heat capacity dependence on temperature of LaBaCoCuMnO6 at 523 K, while LaBaNiCuMnO6 also has a similar effect at 473 K. Equations for the temperature dependence of the heat capacity of cobalt(nickelite)-cuprate-manganite of lanthanum and barium are derived with allowance for the temperatures of phase transitions. Based on the experimental data, the fundamental constants ‒ the standard heat capacities of the compounds under study were found. Irrespective of the experimental data, we also calculated the standard heat capacities of the mentioned compounds using the Debye theory using the characteristic temperatures of the elements, their melting points, the Koref and Nernst-Lindemann equations. The obtained calculated data on C0p (298.15) of the compounds were in satisfactory agreement with the experimental data on the standard heat capacity. The standard entropies of LaBaCoCuMnO6 and LaBaNiCuMnO6 were calculated by the ion increment method. We calculated the temperature dependences of the enthalpy Ho(T)- Ho(298.15), entropy ΔSo(T), and the reduced thermodynamic potential ΔФ**(Т).

scholarly journals A New Four-Parameter Cubic Equation of State for Predicting Fluid Phase Behavior

2019 ◽  
Author(s):  
zhiren he
Keyword(s):  
Heat Capacity ◽  
Equation Of State ◽  
Vapor Pressure ◽  
Saturated Vapor ◽  
Liquid Density ◽  
Saturated Liquid ◽  
Cubic Equation ◽  
Liquid Heat ◽  
Entropy Of Vaporization ◽  
Saturated Liquid Density

<p>A new four-parameter cubic equation of state (EoS) is generated by incorporating the critical compressibility factor (Z<sub>c</sub>) apart from the critical pressure (P<sub>c</sub>) and temperature (T<sub>c</sub>). One free parameter in the denominator of the attractive term and two parameters in the alpha function are adjusted using the experimental data of saturated liquid density, vapor pressure, and isobaric liquid heat capacity of 48 components including hydrocarbons and non-hydrocarbons. Applying this equation of state, saturated liquid density, saturated vapor density, and vapor pressure of pure components are accurately reproduced compared with experimental values. Furthermore, the predicted properties including derivatives of alpha function, such as enthalpy of vaporization, entropy of vaporization and isobaric heat capacity of liquid, also have decent accuracy. The global average absolute relative deviation (AAD) of saturated liquid density, saturated vapor density, saturated vapor pressure, enthalpy of vaporization, entropy of vaporization, and isobaric heat capacity of liquid in a wide reduced temperature (Tr) range of subcritical region reproduced by this work are 4.33%, 4.18%, 3.19%, 2.26%, 2.27%, and 5.82%, respectively. Substantial improvement has been achieved for the isobaric liquid heat capacity calculation.</p>

Heat Capacity of the Rb3LnCl6 Compounds with Ln = La, Ce, Pr, Nd

1999 ◽  
Vol 54 (6-7) ◽  
pp. 397-403 ◽  
Author(s):  
L. Rycerz ◽  
M. Gaune-Escard
Keyword(s):  
Experimental Data ◽  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Liquid Phase ◽  
Formation Enthalpy ◽  
Heat Capacities ◽  
Small Decrease ◽  
Scanning Calorimetry ◽  
Increasing Temperature

Abstract The heat capacities of the solid and liquid Rb3LnCl6 compounds, where Ln = La, Ce, Pr, Nd, have been determined by differential scanning calorimetry (DSC) in the temperature range 300 -1100 K. The heat capacity shows a small decrease with increasing temperature from the temperature of phase transition up to 150 -200 K above this transition for the Rb3CeCl6, Rb3PrCl6 and Rb3NdCl6 compounds. The measured heat capacities were used to calculate the formation enthalpy of the liquid phase. The results obtained compare satisfactorily with the known experimental data.

Heat Capacity of K3LnCl6 Compounds with Ln = La, Ce, Pr, Nd

1999 ◽  
Vol 54 (3-4) ◽  
pp. 229-235 ◽  
Author(s):  
M. Gaune-Escard ◽  
L. Rycerz
Keyword(s):  
Experimental Data ◽  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Phase Transitions ◽  
Liquid Phase ◽  
Temperature Dependence ◽  
Heat Capacities ◽  
Scanning Calorimetry ◽  
The Enthalpy Of Formation

The heat capacities of the solid and liquid K3LnCl6 compounds (Ln = La, Ce, Pr, Nd) have been determined by differential scanning calorimetry (DSC) in the temperature range 300 -1100 K. Their temperature dependence is discussed in terms of the phase transitions of these compounds as reported in literature. The heat capacity increases and decreases strongly in the vicinity of a phase transition but else varies smoothly. The Cp data were fitted by an equation which provides a satisfactory representation up to the temperatures of Cp discontinuity. The measured heat capacities were checked for consistency by calculating the enthalpy of formation of the liquid phase, which had been previously measured. The results obtained compare satisfactorily with these experimental data.

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