http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Mon, 29 Apr 2013 09:04:43 +0000 http://www.hindawi.com/journals/jtd/2013/353841/ Density, refractive index, speed of sound, and viscosity have been measured of binary mixture dimethylsulfoxide (DMSO) + isopropylbenzene (CUMENE) over the whole composition range at 298.15, 303.15, 308.15, and 313.15 K and atmospheric pressure. From these experimental measurements the excess molar volume, deviations in viscosity, molar refractivity, speed of sound, and isentropic compressibility have been calculated. These deviations have been correlated by a polynomial Redlich-Kister equation to derive the coefficients and standard error. The viscosities have furthermore been correlated with two or three parameter models, that is, herric correlation and McAllister model, respectively. Maninder Kumar and V. K. Rattan Copyright © 2013 Maninder Kumar and V. K. Rattan. All rights reserved. Mon, 15 Apr 2013 16:12:39 +0000 http://www.hindawi.com/journals/jtd/2013/828620/ The three-parameter Lennard-Jones potential function is proposed to calculate thermodynamic property (second virial coefficient) and transport properties (viscosity, thermal conductivity, and diffusion coefficient) of noble gases (He, Ne, Ar, Kr, and Xe) and their mixtures at low density. Empirical modification is made by introducing a reduced temperature-correction parameter to the Lennard-Jones potential function for this purpose. Potential parameters (, , and ) are determined individually for each species when the second virial coefficient and viscosity data are fitted together within the experimental uncertainties. Calculated thermodynamic and transport properties are compared with experimental data by using a single set of parameters. The present study yields parameter sets that have more physical significance than those of second virial coefficient methods and is more discriminative than the existing transport property methods in most cases of pure gases and of gas mixtures. In particular, the proposed model is proved with better results than those of the two-parameter Lennard-Jones potential, Kihara Potential with group contribution concepts, and other existing methods. Seung-Kyo Oh Copyright © 2013 Seung-Kyo Oh. All rights reserved. Mon, 25 Mar 2013 10:09:49 +0000 http://www.hindawi.com/journals/jtd/2013/285796/ Speeds of sound and density for binary mixtures of ethyl benzoate (EB) with N,N-dimethylformamide (NNDMF), N,N-dimethyl acetamide (NNDMAc), and N,N-dimethylaniline (NNDMA) were measured as a function of mole fraction at temperatures 303.15, 308.15 K, 313.15 K, and 318.15 K and atmospheric pressure. From the experimental data, adiabatic compressibility (), intermolecular free length (), and molar volume () have been computed. The excess values of the above parameters were also evaluated and discussed in light of molecular interactions. Deviation in adiabatic compressibilities and excess intermolecular free length () are found to be negative over the molefraction of ethyl benzoate indicating the presence of strong interactions between the molecules. The negative excess molar volume values are attributed to strong dipole-dipole interactions between unlike molecules in the mixtures. The binary data of , , and were correlated as a function of molefraction by using the Redlich-Kister equation. B. Nagarjun, A. V. Sarma, G. V. Rama Rao, and C. Rambabu Copyright © 2013 B. Nagarjun et al. All rights reserved. Mon, 25 Feb 2013 10:17:28 +0000 http://www.hindawi.com/journals/jtd/2013/909162/ This paper reports an analytical study of the second law in the case of gas absorption into a laminar falling viscous incompressible liquid film. Velocity, temperature, and concentration profiles are determined and used for the entropy generation calculation. Irreversibilities due to heat transfer, fluid friction, and coupling effects between heat and mass transfer are derived. The obtained results show that entropy generation is mainly due to coupling effects between heat and mass transfer near the gas-liquid interface. Total irreversibility is minimum at the diffusion film thickness. On approaching the liquid film thickness, entropy generation is mainly due to viscous irreversibility. Nejib Hidouri, Imen Chermiti, and Ammar Ben Brahim Copyright © 2013 Nejib Hidouri et al. All rights reserved. Thu, 20 Dec 2012 17:00:22 +0000 http://www.hindawi.com/journals/jtd/2012/246914/ We revisit the problem of optimal power extraction in four-step cycles (two adiabatic and two heat-transfer branches) when the finite-rate heat transfer obeys a linear law and the heat reservoirs have finite heat capacities. The heat-transfer branch follows a polytropic process in which the heat capacity of the working fluid stays constant. For the case of ideal gas as working fluid and a given switching time, it is shown that maximum work is obtained at Curzon-Ahlborn efficiency. Our expressions clearly show the dependence on the relative magnitudes of heat capacities of the fluid and the reservoirs. Many previous formulae, including infinite reservoirs, infinite-time cycles, and Carnot-like and non-Carnot-like cycles, are recovered as special cases of our model. Abhishek Khanna and Ramandeep S. Johal Copyright © 2012 Abhishek Khanna and Ramandeep S. Johal. All rights reserved. Tue, 11 Dec 2012 17:15:58 +0000 http://www.hindawi.com/journals/jtd/2012/580593/ CFD investigation was carried out to study the heat transfer enhancement characteristics of air flow inside a circular tube with a partially decaying and partly swirl flow. Four combinations of tube with twisted-tape inserts, the half-length upstream twisted-tape condition (HLUTT), the half-length downstream twisted-tape condition (HLDTT), the full-length twisted tape (FLTT), and the plain tube (PT) with three different twist parameters (, 0.27, and 0.38) have been investigated. 3D numerical simulation was performed for an analysis of heat transfer enhancement and fluid flow for turbulent regime. The results of CFD investigations of heat transfer and friction characteristics are presented for the FLTT, HLUTT, and the HLDTT in comparison with the PT case. R. J. Yadav and A. S. Padalkar Copyright © 2012 R. J. Yadav and A. S. Padalkar. All rights reserved. Sun, 09 Dec 2012 15:10:47 +0000 http://www.hindawi.com/journals/jtd/2012/892696/ The temperature dependence of the 501 cm−1 frequency of the vibrational mode is analyzed for SiO2-moganite. The experimental data for the heating and cooling cycles of moganite from the literature is used for our analysis. The coexistence of α-β moganite is obtained over a finite temperature interval, and the α-β moganite transition at around 570 K is studied, as observed experimentally. Mustafa Cem Lider and Hamit Yurtseven Copyright © 2012 Mustafa Cem Lider and Hamit Yurtseven. All rights reserved. Thu, 29 Nov 2012 10:56:08 +0000 http://www.hindawi.com/journals/jtd/2012/879390/ In the present study analytical solution for forced convection heat transfer in a circular duct with a special boundary condition has been presented, because the external wall temperature is a periodic function of axial direction. Local energy balance equation is written with reference to the fully developed regime. Also governing equations are two-dimensionally solved, and the effect of duct wall thickness has been considered. The temperature distribution of fluid and solid phases is assumed as a periodic function of axial direction and finally temperature distribution in the flow field, solid wall, and local Nusselt number, is obtained analytically. M. R. Astaraki and N. Ghiasi Tabari Copyright © 2012 M. R. Astaraki and N. Ghiasi Tabari. All rights reserved. Tue, 13 Nov 2012 17:14:17 +0000 http://www.hindawi.com/journals/jtd/2012/892913/ We examine here the validity of the Pippard relations close to the melting point in the premelting region of hexadecane. For this verification, we analyze the observed data for the thermal expansivity obtained for various pressures at constant temperatures of 302 and 325 K in this system. By calculating the isothermal compressibility and the specific heat in the same pressure region of the premelting region of hexadecane, we obtain that varies linearly with and also that varies linearly with for this system. This indicat es that some molecular organic compounds, such as solid hexadecane studied here, can exhibit -phase transitions prior to melting which are expected to verify the Pippard relations. Hamit Yurtseven, Özcan Tilki, and Mustafa Kurt Copyright © 2012 Hamit Yurtseven et al. All rights reserved. Sun, 11 Nov 2012 10:38:29 +0000 http://www.hindawi.com/journals/jtd/2012/109132/ The complexation reactions between aza-18-crown-6 (A18C6) and Co2+, Ni2+, Cu2+, and Zn2+ ions were studied conductometrically in different acetonitrile-methanol mixtures at various temperatures. The formation constants of the resulting 1 : 1 complexes were calculated from the computer fitting of the molar conductance-mole ratio data at different temperatures. Selectivity of A18C6 for Co2+, Ni2+, Cu2+, and Zn2+ cations is sensitive to the solvent composition. At 20°C and in acetonitrile solvent, the stability of the resulting complexes varied in the order but the order was reversed byadding 20% methanol. The enthalpy and entropy changes of the complexation reactions were evaluated from the temperature dependence of formation constants. It was found that the stability of the resulting complexes decreased with increasing methanol in the solvent mixture. The TΔS° versus ΔH° plot of thermodynamic data obtained shows a fairly good linear correlation indicating the existence of enthalpy-entropy compensation in the complexation reactions. In addition, binding energies of Ni2+, Cu2+, and Zn2+ complexes with A18C6 were calculated at B3LYP/6-31G level of theory. Mehdi Taghdiri, Mahmood Payehghadr, Reza Behjatmanesh-Ardakani, and Homa Gha'ari Copyright © 2012 Mehdi Taghdiri et al. All rights reserved. Mon, 05 Nov 2012 09:40:06 +0000 http://www.hindawi.com/journals/jtd/2012/318032/ In a previous paper (Ryazanov (2011)) with the joint statistical distribution for the energy and lifetime (time to achieve a given level of a stochastic process for energy of system) to derive thermodynamic relationships, clarifying similar expressions of extended irreversible thermodynamics we used an exponential distribution of lifetime. In this paper, we explore a more realistic expression for the distribution of time to achieve a given level of a stochastic process for energy of system (or relaxation times or lifetimes), and we analyse how such distribution affects the corresponding expressions of nonequilibrium entropy, temperature, and entropy production. V. V. Ryazanov Copyright © 2012 V. V. Ryazanov. All rights reserved. Wed, 10 Oct 2012 13:55:06 +0000 http://www.hindawi.com/journals/jtd/2012/641251/ Vapor-liquid equilibrium (VLE) data for the strongly associated ternary system methanol + water + ethanoic acid and the three constituent binary systems have been determined by the total pressure-temperature-liquid-phase composition-molar excess enthalpy of mixing of the liquid phase (, , , ) for the binary systems using a novel pump ebulliometer at 101.325 kPa. The vapor-phase compositions of these binary systems had been calculated from and based on the function of molar excess Gibbs energy through an indirect method. Moreover, the experimental , data are used to estimate nonrandom two-liquid (NRTL), Wilson, Margules, and van Laar model parameters, and these parameters in turn are used to calculate vapor-phase compositions. The activity coefficients of the solution were correlated with NRTL, Wilson, Margules, and van Laar models through fitting by least-squares method. The VLE data of the ternary system were well predicted from these binary interaction parameters of NRTL, Wilson, Margules, and van Laar model parameters without any additional adjustment to build the thermodynamic model of VLE for the ternary system and obtain the vapor-phase compositions and the calculated bubble points. Daming Gao, Hui Zhang, Peter Lücking, Hong Sun, Jingyu Si, Dechun Zhu, Hong Chen, and Jianjun Shi Copyright © 2012 Daming Gao et al. All rights reserved. Thu, 30 Aug 2012 10:11:04 +0000 http://www.hindawi.com/journals/jtd/2012/725142/ The problem of combined heat and mass transfer by natural convection over a sphere in a homogenous non-Darcian porous medium subjected to uniform magnetic field is numerically studied, taking Soret/Dufour effects into account. The coupled, steady, and laminar partial differential conservation equations of mass, momentum, energy, and species diffusion are normalized with appropriate transformations. The resulting well-posed two-point boundary value problem is solved using the well-tested, extensively validated Keller-Box implicit finite difference method, with physically realistic boundary conditions. A parametric study of the influence of Soret number (Sr), Dufour number (Du), Forchheimer parameter (Λ), Darcy parameter (Da), buoyancy ratio parameter (𝑁), Prandtl number (Pr), Schmidt number (Sc), magnetohydrodynamic body force parameter (𝑀), wall transpiration (𝑓𝑤) is the blowing/suction parameter, and streamwise variable (ξ) on velocity, temperature, and concentration function evolution in the boundary layer regime is presented. Shear stress, Nusselt number, and Sherwood number distributions are also computed. Applications of the study arise in hydromagnetic flow control of conducting transport in packed beds, magnetic materials processing, geophysical energy systems, and magnetohydrodynamic chromatography technology. B. Vasu, V. R. Prasad, and O. Anwar Bég Copyright © 2012 B. Vasu et al. All rights reserved. Mon, 30 Jul 2012 11:46:03 +0000 http://www.hindawi.com/journals/jtd/2012/432143/ Signal transduction inside and across the cells, also called cellular signaling, is key to most biological functions and is ultimately related with both life and death of the organisms. The processes giving rise to the propagation of biosignals are complex and extremely cooperative and occur in a far-from thermodynamic equilibrium regime. They are also driven by activation kinetics strongly dependent on local energetics. For these reasons, a nonequilibrium thermodynamical description, taking into account not just the activation of second messengers, but also transport processes and dissipation is desirable. Here we present a proposal for such a formalism, that considers cells as small thermodynamical systems and incorporates the role of fluctuations as intrinsic to the dynamics in a spirit guided by mesoscopic nonequilibrium thermodynamics. We present also a minimal model for cellular signaling that includes contributions from activation, transport, and intrinsic fluctuations. We finally illustrate its feasibility by considering the case of FAS signaling which is a vital signal transduction pathway that determines either cell survival or death by apoptosis. Enrique Hernández-Lemus Copyright © 2012 Enrique Hernández-Lemus. All rights reserved. Wed, 14 Mar 2012 11:40:44 +0000 http://www.hindawi.com/journals/jtd/2012/723052/ The compact thermodynamic approach to the systems containing calcium, magnesium, and carbonate species is referred to dissolution of dolomite, as an example of nonequilibrium ternary salt when introduced into aqueous media. The study of dolomite is based on all attainable physicochemical knowledge, involved in expressions for equilibrium constants, where the species of the system are interrelated. The species are also involved in charge and concentration balances, considered as constraints put on a closed system, separated from the environment by diathermal walls. The inferences are gained from calculations performed with use of an iterative computer program. The simulated quasistatic processes occurred under isothermal conditions, started at a preassumed pH0 value of the solution where dolomite was introduced, and are usually involved with formation of other solid phases. None simplifying assumptions in the calculations were made. Tadeusz Michalowski and Agustin G. Asuero Copyright © 2012 Tadeusz Michałowski and Agustin G. Asuero. All rights reserved. Thu, 08 Mar 2012 13:08:02 +0000 http://www.hindawi.com/journals/jtd/2012/125460/ Reactions associated with removal of oxygen from oxygenates (deoxygenation) are an important aspect of hydrocarbon fuels production process from biorenewable substrates. Here we report the equilibrium composition of methanol-to-hydrocarbon system by minimizing the total Gibbs energy of the system using Cantera methodology. The system was treated as a mixture of 14 components which had CH3OH, C6H6, C7H8, C8H10 (ethyl benzene), C8H10 (xylenes), C2H4, C2H6, C3H6, CH4, H2O, C, CO2, CO, H2. The carbon in the equilibrium mixture was used as a measure of coke formation which causes deactivation of catalysts that are used in aromatization reaction(s). Equilibrium compositions of each species were analyzed for temperatures ranging from 300 to 1380 K and pressure at 0–15 atm gauge. It was observed that when the temperature increases the mole fractions of benzene, toluene, ethylbenzene, and xylene pass through a maximum around 1020 K. At 300 K the most abundant species in the system were CH4, CO2, and H2O with mole fractions 50%, 16.67%, and 33.33%, respectively. Similarly at high temperature (1380 K), the most abundant species in the system were H2 and CO with mole fractions 64.5% and 32.6% respectively. The pressure in the system shows a significant impact on the composition of species. Duminda A. Gunawardena and Sandun D. Fernando Copyright © 2012 Duminda A. Gunawardena and Sandun D. Fernando. All rights reserved. Mon, 05 Mar 2012 15:44:00 +0000 http://www.hindawi.com/journals/jtd/2012/870631/ The ideal gas (IG) model is probably the most well-known gas models in engineering thermodynamics. In this paper, we extend the IG model into an ideal gas equilibrium (IGE model) mixture model by incorporating chemical equilibrium calculations as part of the state evaluation. Through a simple graphical interface, users can set the atomic composition of a gas mixture. We have integrated this model into a thermodynamic web portal TEST (http://thermofluids.sdsu.edu/) that contains Java applets for various models for properties of pure substances. In the state panel of the IGE model, the known thermodynamic properties are entered. For a given pressure and temperature, the mixture's Gibbs function is minimized subject to atomic constraints and the equilibrium composition along with thermodynamic properties of the mixture are calculated and displayed. What is unique about this approach is that equilibrium computations are performed in the background, without requiring any major change in the familiar user interface used in other state daemons. Properties calculated by this equilibrium state daemon are compared with results from other established applications such as NASA CEA and STANJAN. Also, two different algorithms, an iterative approach and a direct approach based on minimizing different thermodynamic functions in different situation, are compared. Christopher P. Paolini and Subrata Bhattacharjee Copyright © 2012 Christopher P. Paolini and Subrata Bhattacharjee. All rights reserved. Thu, 01 Mar 2012 10:32:43 +0000 http://www.hindawi.com/journals/jtd/2012/859047/ The equilibrium molecular interactions in pure real gases are investigated based on the chemical thermodynamics principles. The parallels between clusters in real gases and chemical compounds in equilibrium media have been used to improve understanding of the real gas structure. A new approach to the equilibrium constants for the cluster fractions and new methods to compute them and their significant parameters from the experimental thermophysical data are developed. These methods have been applied to some real gases, such as Argon and Water vapors and gaseous Alkanes. It is shown that the four-particle clusters make a noticeable contribution in the thermophysical properties of the equilibrium Water vapor. It is shown also that the effective bond energy for dimers in Alkanes linearly grows with the number of carbon atoms in the molecule. Boris I. Sedunov Copyright © 2012 Boris I. Sedunov. All rights reserved. Sun, 19 Feb 2012 13:59:25 +0000 http://www.hindawi.com/journals/jtd/2012/798104/ Thermodynamic conditions of the heat release process under Diesel engine-like conditions in a real porous combustion reactor simulated in a special combustion chamber were analyzed. The same analyses were performed for a free volume combustion chamber, that is, no porous reactor is applied. A common rail Diesel injection system was used for simulation of real engine fuel injection process and mixture formation conditions. The results show that thermodynamic of the heat release process depends on reactor heat capacity, pore density, specific surface area, and pore structure, that is, on heat accumulation in solid phase of porous reactor. In real reactor, the gas temperature and porous reactor temperature are not equal influenced by initial pressure and temperature and by reactor parameters. It was found that the temperature of gas trapped in porous reactor volume during the heat release process is less dependent on air-to-fuel-ratio than that observed for free volume combustion chamber, while the maximum combustion temperature in porous reactor is significantly low. As found this temperature depends on reactor heat capacity, mixture formation conditions and on initial pressure. Qualitative behavior of heat release process in porous reactors and in free volume combustion chamber is similar, also the time scale of the process. M. Weclas, J. Cypris, and T. M. A. Maksoud Copyright © 2012 M. Weclas et al. All rights reserved. Thu, 09 Feb 2012 09:35:13 +0000 http://www.hindawi.com/journals/jtd/2012/574596/ This article provided a research for the trend of heat transfer and flow field through a 2-dimensional wavy duct. To construct a grid mesh, the physical domain was transferred to the computational domain and finite volume scheme was used for discretizing the governing equations. Through the simulation, the flow regime stayed in laminar mode. Constant temperature boundary condition has been used for solid walls. Air was used as a working fluid. Existence of waves makes some phenomenon like flow separation. Effect of Reynolds number, wave width, and wave number has been analyzed and velocity distribution, heat transfer coefficient, and tangential stress were computed for different cases. The final results were compared with the same straight duct. The entropy generation minimization method has been used for better comparison between final results. Ouldouz Nourani Zonouz and Mehdi Salmanpour Copyright © 2012 Ouldouz Nourani Zonouz and Mehdi Salmanpour. All rights reserved. Thu, 05 Jan 2012 09:05:40 +0000 http://www.hindawi.com/journals/jtd/2012/791870/ The accretion of relativistic and nonrelativistic fluids into a Reissner-Nordström black hole is revisited. The position of the critical point, the flow velocity at this point, and the accretion rate are only slightly affected with respect to the Schwarzschild case when the fluid is nonrelativistic. On the contrary, relativistic fluids cross the critical point always subsonically. In this case, the sonic point is located near the event horizon, which is crossed by the fluid with a velocity less than the light speed. The accretion rate of relativistic fluids by a Reissner-Nordström black hole is reduced with respect to those estimated for uncharged black holes, being about 60% less for the extreme case (charge-to-mass ratio equal to one). J. A. de Freitas Pacheco Copyright © 2012 J. A. de Freitas Pacheco. All rights reserved. Thu, 24 Nov 2011 09:57:55 +0000 http://www.hindawi.com/journals/jtd/2012/351968/ A water desorption process of a mixture of room temperature ionic liquid (N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate) and water was investigated via simultaneous X-ray diffraction and differential scanning calorimetry (DSC) measurements, in which relative humidity was controlled by a water vapor generator. In these measurements, H2O concentration was estimated by the peak position of the principal peak in X-ray diffraction patterns, and the thermal property associated with a mixing state was detected by a DSC thermograph. In addition, the density of the mixture was measured as a macroscopic property. In situ observations revealed that the thermally unstable mixing state in the water-rich region has an important correlation with density and thermal and structural properties. Hiroshi Abe, Tomohiro Mori, Yusuke Imai, and Yukihiro Yoshimura Copyright © 2012 Hiroshi Abe et al. All rights reserved. Tue, 22 Nov 2011 10:11:52 +0000 http://www.hindawi.com/journals/jtd/2011/432132/ The experimental evaluation of the vapor pressure of saturated aqueous solutions of potassium sulfate was carried out in the range of temperatures 310K≤𝑇≤345K. The experimental data were used to determine the corresponding values of the water activity in such solutions. The analytical expressions as a function of temperature of both, vapor pressure and water activity, were obtained from the correlation of the experimental results. The vapor pressure expression was also extrapolated to a different temperature range in order to make a comparison with the results obtained by other authors. Matias O. Maggiolo, Francisco J. Passamonti, and Abel C. Chialvo Copyright © 2011 Matias O. Maggiolo et al. All rights reserved. Wed, 16 Nov 2011 09:02:20 +0000 http://www.hindawi.com/journals/jtd/2011/137531/ The effects of synthetic food colorants like tartrazine (TTZ), sunset yellow (SY), and erythrosine (ETS) on the binding reaction between ciprofloxacin hydrochloride (CPFX) and bovine serum albumin (BSA) were investigated by fluorescence spectroscopy in the aqueous solution of pH = 7.40. Results showed that CPFX caused the fluorescence quenching of BSA through a static quenching procedure and the primary binding site was located at subdomain IIA of BSA (site I). According to the calculated thermodynamic parameters, it confirmed that CPFX bound to BSA by electrostatic interaction. In addition, the colorants affected the formation of BSA-CPFX complex. This resulted in an increase of the free, biological active fraction of CPFX. The binding distance of BSA-CPFX systems was evaluated according to Förster's theory. Results suggested that the binding distance were increased in the presence of synthetic food colorants. Baosheng Liu, Chao Yang, Jing Wang, Chunli Xue, and Yunkai Lü Copyright © 2011 Baosheng Liu et al. All rights reserved. Mon, 14 Nov 2011 10:43:30 +0000 http://www.hindawi.com/journals/jtd/2012/575728/ By a simple differential thermal analysis (DTA) system, the concentration dependence of the glass transition temperatures (𝑇𝑔s) for the quaternary ammonium-type ionic liquid, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bromide [DEME][Br] and H2O mixtures, after quick precooling was measured as a function of water concentration 𝑥 (mol% H2O). We compared the results with the previous results of [DEME][I]-H2O and [DEME][BF4]-H2O mixtures in which a double-glass transition behavior was observed. Remarkably, the [DEME][Br]-H2O mixtures basically show one-𝑇𝑔 behavior and the 𝑇𝑔 decreases monotonically with increasing H2O content up to around 𝑥=91.5. But it suddenly jumps to higher 𝑇𝑔 value at a specific 𝑥=∼92. At this very limited point, two 𝑇𝑔s (𝑇𝑔1,𝑇𝑔2) which we might consider as a transition state from the structure belonging to the 𝑇𝑔1 group to another one due to the 𝑇𝑔2 group were observed. These results clearly reflect the difference in the anionic effects among Br−, I−, and BF4−. The end of the glass-formation region of [DEME][Br]-H2O mixtures is around 𝑥=98.9 and moves to more water-rich region as compared to those of [DEME][BF4]-H2O (𝑥=96.0) and [DEME][I]-H2O (𝑥=95.0) mixtures. Yukihiro Yoshimura, Naohiro Hatano, Yusuke Imai, Hiroshi Abe, Osamu Shimada, and Tomonori Hanasaki Copyright © 2012 Yukihiro Yoshimura et al. All rights reserved. Thu, 10 Nov 2011 12:00:31 +0000 http://www.hindawi.com/journals/jtd/2011/203203/ To describe the nonequilibrium states of a system, we introduce a new thermodynamic parameter—the lifetime of a system. The statistical distributions which can be obtained out of the mesoscopic description characterizing the behaviour of a system by specifying the stochastic processes are written down. The change in the lifetime values by interaction with environment is expressed in terms of fluxes and sources. The expressions for the nonequilibrium entropy, temperature, and entropy production are obtained, which at small values of fluxes coincide with those derived within the frame of extended irreversible thermodynamics. The explicit expressions for the lifetime of a system and its thermodynamic conjugate are obtained. Vasiliy Vasiliy Ryazanov Copyright © 2011 Vasiliy Vasiliy Ryazanov. All rights reserved. Wed, 02 Nov 2011 14:18:43 +0000 http://www.hindawi.com/journals/jtd/2011/282354/ The phase behaviour of mixtures of supercritical propene and a number of polypropenes, which have a similar density but significantly different molecular weights and tacticities, was investigated in a broad range of polymer weight fractions and temperatures at high pressures. The cloud-point pressures were measured optically, using a view cell which was equipped with two windows made of synthetic sapphire and a metal bellows to accurately adjust the pressure. The cloud-point pressures were found in the range from 29 to 37 MPa decreasing with increasing polymer weight fraction and increasing with increasing temperature and polymer molecular weight. The critical weight fraction was found below 2 to 6 wt.-%. Whereas the cloud-point pressures of atactic and syndiotactic samples were high and very similar, the isotactic species exhibit distinctly lower values. The results, extrapolated to lower temperatures, show good agreement with the literature data. Oliver Ruhl, Gerhard Luft, Patrick Brant, and John Richard Shutt Copyright © 2011 Oliver Ruhl et al. All rights reserved. Sat, 29 Oct 2011 17:24:42 +0000 http://www.hindawi.com/journals/jtd/2011/676495/ We formulate the thermodynamics of economic systems in terms of an arbitrary probability distribution for a conserved economic quantity. As in statistical physics, thermodynamic macroeconomic variables emerge as the mean value of microeconomic variables, and their determination is reduced to the computation of the partition function, starting from an arbitrary function. Explicit hypothetical examples are given which include linear and nonlinear economic systems as well as multiplicative systems such as those dominated by a Pareto law distribution. It is shown that the macroeconomic variables can be drastically changed by choosing the microeconomic variables in an appropriate manner. We propose to use the formalism of phase transitions to study severe changes of macroeconomic variables. Hernando Quevedo and María N. Quevedo Copyright © 2011 Hernando Quevedo and María N. Quevedo. All rights reserved. Wed, 12 Oct 2011 08:58:00 +0000 http://www.hindawi.com/journals/jtd/2011/696548/ 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. Isam H. Aljundi Copyright © 2011 Isam H. Aljundi. All rights reserved. Mon, 10 Oct 2011 08:23:52 +0000 http://www.hindawi.com/journals/jtd/2011/194353/ The extension of the saturation curve 𝑃𝑠(𝑇) on the PT diagram in the supercritical region for a number of monocomponent supercritical fluids by peak values for different thermophysical properties, such as heat capacities 𝐶𝑝 and 𝐶𝑣 and compressibility has been studied. These peaks signal about some sort of fluid structural transition in the supercritical region. Different methods give similar but progressively diverging curves 𝑃st(𝑇) for this transition. The zone of temperatures and pressures near these curves can be named as the zone of the fluid structural transition. The outstanding properties of supercritical fluids in this zone help to understand the physical sense of the fluid structural transition. Boris I. Sedunov Copyright © 2011 Boris I. Sedunov. All rights reserved.