International Journal of Thermodynamics

The purpose and scope of the International Journal of Thermodynamics is to provide a forum for the publication of original theoretical and applied work in the field of thermodynamics as it relates to systems, states, processes, and both non-equilibrium and equilibrium phenomena at all temporal and spatial scales. The journal, thus, provides a multidisciplinary and international platform for the dissemination to academia and industry of both scientific and engineering contributions, which touch upon a broad class of disciplines that are foundationally linked to thermodynamics and the methods and analyses derived there from. A common thread throughout is that of assessing how both the first and particularly the second laws of thermodynamics touch upon these disciplines.



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Vol 17, No 2: June 2014

Table of Contents

Regular Original Research Article

Non-equilibrium Thermodynamic Extension of the Phenomenological Theories of First-order Phase Transitions PDF
Shutao Ai, Yuanzhen Cai 53-59
Because the phenomenological theories of phase transitions which are based on the equilibrium thermodynamics cannot describe the first-order phase transition processes accurately, the non-equilibrium thermodynamics was applied to extending the existing phenomenological theories of first-order phase transitions. First, the internal interactions of system at a first-order phase transition were considered. The nominal stress, the nominal volume force, the internal electric field and the internal magnetic field were introduced to characterize them. Then, the most general Gibbs equation except the factor of chemical reactions was established. Based on the conservation of energy and the transformation between internal energy and kinetic energy, the rate of local entropy production was deduced. Then based on the principle of minimum entropy production and the generalized Onsager reciprocal relations, the local, evolving characteristics of a first-order phase transition (e.g. a first-order ferroelectric phase transition) were described well. It makes up the inadequateness of the older phenomenological theories.
Thermodynamics of protein unfolding-refolding transition PDF
Jeanfils Joseph, Anakkar Abdelkader, Buisine Jean-Marc 61-69
A phenomenological thermodynamic model is developed to investigate, in more detail than usual, the pressure-temperature phase diagram of proteins. Indeed, in the whole of previous studies the specific heat difference deltaCP is treated as pressure and temperature independent. This assumption is wrong, as confirmed by Yamaguchi et al (1995) which reported pressure dependence of deltaCP in the case of ribonuclease A. In this work, assuming that the chemical potential has a Taylor series expansion and having an additional thermodynamic piece of information, the analysis shows that it is possible to obtain a complete description of the unfolding-refolding transition of protein, to deduce the volumes, entropies, enthalpies versus transition temperatures and transition pressures and, for the first time, to deduce the specific heat changes versus transition temperatures and transition pressures. Special attention is given to the elliptical shape of the pressure-temperature phase diagram. A quantitative description of the phase transitions in the protein of Zn-Cytochrome c is given.
A review on thermodynamic optimization of irreversible refrigerator and verification with transcritical CO2 system PDF
Jahar Sarkar 71-79
The transcritical vapor compression refrigeration cycle consists of isothermal heat addition process and isobaric non-isothermal heat rejection process with highly variable heat capacity unlike to the subcritical cycle. Hence, it is quite interesting whether the analysis and optimization results of irreversible Carnot-like refrigerator are applicable for this case. The present study consists of two parts: the detailed review on theoretical analysis and analytical optimizations of irreversible Carnot-like refrigerator with both infinite and finite capacity heat reservoirs, and verification of analytical results with the results obtained from a more elaborate numerical simulation of transcritical CO2 refrigeration system. Considered objective parameters are cooling load or COP and overall heat transfer surface area, and optimizing parameters are cold and hot side working fluid temperatures, ratio of residence times for heat addition and heat rejection, and heat transfer surface area ratio. Reasonably fair agreement has been obtained between analytical and numerical model predictions.
Modeling the Solubility of Dihydroxybenzoic Acid and Methylbenzoic Acid Isomers in Supercritical Carbon Dioxide PDF
loubna nasri, salima bensaad, zouhir bensetiti 81-85
In this work, we propose to correlate and predict the solubility in supercritical CO2 of disubstituted aromatic isomers of hydroxybenzoic acid and methylbenzoic acid with a new methodology based on the expanded liquid theory, in which the solid–fluid equilibrium is modeled using the local composition model of UNIQUAC in which the interaction parameters are related to the solvent reduced density with an empiric exponential form equations. The experimental solubility of hydroxybenzoic acid isomers, methylbenzoic acid isomers and mixed isomers (m-hydroxybenzoic acid+p-hydroxybenzoic acid) are used for evaluating the correlation and prediction capabilities of this new methodology. The results obtained using the proposed model show good agreement with the experimental data used.
Modeling of a pressurized entrained-flow coal gasifier for power plant simulation PDF
Michael Krüger 87-95
Now and in the mid-term future, coal remains an important energy source for electricity generation for reasons of energy supply security and economics. The expectation to get low CO2-emissions and high plant efficiencies, particularly independently of coal quality, makes coal gasification an essential part of numerous innovative power plant concepts. For that reason, simplified and flexible models for coal gasifiers are needed, which can be implemented easily in complex power plant system simulations. A model for an entrained-flow coal gasifier, the Prenflo coal gasification process, based on an equilibrium approach is developed. The created model is validated with operation data published in literature of a demonstration plant in Fürstenhausen (Germany). For all published plant parameters, the calculated values of the model reproduce the operating data fairly precisely. Parametric study for the target application in a hybrid power plant including high temperature fuel cells regarding the gasification temperature and pressure as well as the mass flow ratios of the gasifying agent to coal is presented. Influences of these parameters on product gas composition and efficiency of gasification are investigated. By means of these, the model of the coal gasifier is qualified for implementation in system models such as those of integrated gasification combined cycle and hybrid power plants including high temperature fuel cells.
Energetic and Exergetic Performance Analyses of Solar Dish Based CO2 Combined Cycle PDF
Soumitra Mukhopadhyay, Sudip Ghosh 97-105
This paper presents a conceptual configuration of a solar dish based combined cycle power plant with a topping gas turbine block and a bottoming steam turbine cycle coupled through a heat recovery steam generator (HRSG). Carbon dioxide has been considered as the working fluid for the topping cycle and it has been considered in gaseous state all through the cycle. Two-stage compression has been proposed for the carbon dioxide cycle. The conventional GT combustion chamber is replaced by a high-temperature directly irradiated annular pressurized receiver (DIAPR) consisting of cavity and tubular sections. Detail thermodynamic study has been performed for varying second stage pressure ratio and for varying gas turbine inlet temperature for the combined cycle keeping first stage pressure ratio fixed at 3.The gas turbine inlet temperature has been varied from 625 to 900 degree C. The study reveals that work output of the combined cycle is maximum when the pressure ratio of the second stage compression is 2. Parametric exergetic analysis has also been performed for the components like dish, solar receiver and stack. The exergy analysis shows that the solar receiver contributes to maximum exergy destruction.
Vehicle Level Tip-to-Tail Modeling of an Aircraft PDF
Rory A Roberts, Scott M Eastbourn 107-115
A system-level multidisciplinary aircraft model has been developed exclusively in MATLAB/Simulink. Aircraft subsystem models representing the air vehicle system, propulsion system, robust electrical power system, thermal management systems, actuation system and their associated controllers were integrated to investigate the thermal management issues of a long range strike platform. The aircraft model coined tip-to-tail modeling and simulation tool (T2T M&S) allows conceptual design trade studies of various subsystems and can quantify performance gains across the aircraft. As a result, the thermal and power challenges that face modern aircraft can be addressed, potentially increasing the performance capabilities of future aircraft. Preliminary simulation results are discussed with a specific focus on thermal management during mission segments of high thermal demands.

ISSN: 2146-1511
©  International Journal of Thermodynamics