Showing papers on "Entropy (classical thermodynamics) published in 1988"
Book•
30 Apr 1988
TL;DR: In this article, the authors present an overview of the second law of thermodynamics and its application in the context of a gas turbine power plant and evaluate the entropy of the system.
Abstract: 1 Getting Started: Introductory Concepts and Definitions. 1.1 Using Thermodynamics. 1.2 Defining Systems. 1.3 Describing Systems and Their Behavior. 1.4 Measuring Mass, Length, Time, and Force. 1.5 Specific Volume. 1.6 Pressure. 1.7 Temperature. Chapter Summary and Study Guide. 2 Energy and the First Law of Thermodynamics. 2.1 Reviewing Mechanical Concepts of Energy. 2.2 Broadening Our Understanding of Work. 2.3 Broadening Our Understanding of Energy. 2.4 Energy Transfer by Heat. 2.5 Energy Accounting: Energy Balance for Closed Systems. 2.6 Energy Analysis of Cycles. Chapter Summary and Study Guide. 3 Evaluating Properties. 3.1 Getting Started. Evaluating Properties: General Considerations. 3.2 p-v-T Relation. 3.3 Studying Phase Change. 3.4 Retrieving Thermodynamic Properties. 3.5 Evaluating Pressure, Specific Volume, and Temperature. 3.6 Evaluating Specific Internal Energy and Enthalpy. 3.7 Evaluating Properties Using Computer Software. 3.8 Applying the Energy Balance Using Property Tables and Software. Chapter Summary and Study Guide. 4 Control Volume Analysis Using Energy. 4.1 Conservation of Mass for a Control Volume. 4.2 Forms of the Mass Rate Balance. 4.3 Applications of the Mass Rate Balance. 4.4 Conservation of Energy for a Control Volume. Chapter Summary and Study Guide. 5 The Second Law of Thermodynamics. 5.1 Introducing the Second Law. 5.2 Statements of the Second Law. 5.3 Identifying Irreversibilities. 5.4 Interpreting the Kelvin-Planck Statement. 5.5 Applying the Second Law to Thermodynamic Cycles. 5.6 Second Law Aspects of Power Cycles Interacting with Two Reservoirs. Chapter Summary and Study Guide. 6 Using Entropy. 6.1 Entropy-A System Property. 6.2 Retrieving Entropy Data. 6.3 Introducing the T dS Equations. 6.4 Entropy Change of an Incompressible Substance. 6.5 Entropy Change of an Ideal Gas. 6.6 Entropy Change in Internally Reversible Processes of Closed Systems. 6.7 Entropy Balance for Closed Systems. 6.8 Directionality of Processes. 6.9 Entropy Rate Balance for Control Volumes. Steady-State Flow Processes. Chapter Summary and Study Guide. 7 Exergy Analysis. 7.1 Introducing Exergy. 7.2 Conceptualizing Exergy. 7.3 Exergy of a System. 7.4 Closed System Exergy Balance. 7.5 Exergy Rate Balance for Control Volumes at Steady State. 7.6 Exergetic (Second Law) Efficiency. 7.7 Thermoeconomics. Chapter Summary and Study Guide. 8 Vapor Power Systems. 8.1 Modeling Vapor Power Systems. 8.2 Analyzing Vapor Power Systems-Rankine Cycle. 8.3 Improving Performance-Superheat and Reheat. 8.4 Improving Performance-Regenerative Vapor Power Cycle. 8.5 Other Vapor Cycle Aspects. 8.6 Case Study: Exergy Accounting of a Vapor Power Plant. Chapter Summary and Study Guide. 9 Gas Power Systems. Internal Combustion Engines. 9.1 Introducing Engine Terminology. 9.2 Air-Standard Otto Cycle. 9.3 Air-Standard Diesel Cycle. 9.4 Air-Standard Dual Cycle. Gas Turbine Power Plants. 9.5 Modeling Gas Turbine Power Plants. 9.6 Air-Standard Brayton Cycle. 9.7 Regenerative Gas Turbines. 9.8 Regenerative Gas Turbines with Reheat and Intercooling. 9.9 Gas Turbines for Aircraft Propulsion. 9.10 Combined Gas Turbine-Vapor Power Cycle. Chapter Summary and Study Guide. 10 Refrigeration and Heat Pump Systems. 10.1 Vapor Refrigeration Systems. 10.2 Analyzing Vapor-Compression Refrigeration Systems. 10.3 Refrigerant Properties. 10.4 Cascade and Multistage Vapor-Compression Systems. 10.5 Absorption Refrigeration. 10.6 Heat Pump Systems. 10.7 Gas Refrigeration Systems. Chapter Summary and Study Guide. 11 Thermodynamic Relations. 11.1 Using Equations of State. 11.2 Important Mathematical Relations. 11.3 Developing Property Relations. 11.4 Evaluating Changes in Entropy, Internal Energy, and Enthalpy. 11.5 Other Thermodynamic Relations. 11.6 Constructing Tables of Thermodynamic Properties. Charts for Enthalpy and Entropy. 11.8 p-v-T Relations for Gas Mixtures. 11.9 Analyzing Multicomponent Systems. Chapter Summary and Study Guide. 12 Ideal Gas Mixture and Psychrometric Applications. Ideal Gas Mixtures: General Considerations. 12.1 Describing Mixture Composition. 12.2 Relating p, V, and T for Ideal Gas Mixtures. 12.3 Evaluating U, H, S, and Specific Heats. 12.4 Analyzing Systems Involving Mixtures. Psychrometric Applications. 12.5 Introducing Psychrometric Principles. 12.6 Psychrometers: Measuring the Wet-Bulb and Dry-Bulb Temperatures. 12.7 Psychrometric Charts. 12.8 Analyzing Air-Conditioning Processes. 12.9 Cooling Towers. Chapter Summary and Study Guide. 13 Reacting Mixtures and Combustion. Combustion Fundamentals. 13.1 Introducing Combustion. 13.2 Conservation of Energy-Reacting Systems. 13.3 Determining the Adiabatic Flame Temperature. 13.4 Fuel Cells. 13.5 Absolute Entropy and the Third Law of Thermodynamics. Chemical Exergy. 13.6 Introducing Chemical Exergy. 13.7 Standard Chemical Exergy. 13.8 Exergy Summary. 13.9 Exergetic (Second Law) Efficiencies of Reacting Systems. Chapter Summary and Study Guide. 14 Chemical and Phase Equilibrium. Equilibrium Fundamentals. 14.1 Introducing Equilibrium Criteria. Chemical Equilibrium. 14.2 Equation of Reaction Equilibrium. 14.3 Calculating Equilibrium Compositions. 14.4 Further Examples of the Use of the Equilibrium Constant. Phase Equilibrium. 14.5 Equilibrium Between Two Phases of a Pure Substance. 14.6 Equilibrium of Multicomponent, Multiphase Systems. Chapter Summary and Study Guide. Appendix Tables, Figures, and Charts. Index to Tables in SI Units. Index to Tables in English Units. Index to Figures and Charts. Index. Answers to Selected Problems: Visit the student.
2,775 citations
TL;DR: In this article, the thermodynamics of thermoelastic martensitic transformations are reformulated from the point of view of calorimetric experiments, and it is shown that the heat released or absorbed by the specimen is due to a triple contribution: the latent heat of transformation, the reversibly stored elastic enthalpy and the irreversible work mainly spent in moving the interfaces.
295 citations
Journal Article•
114 citations
TL;DR: In this article, heat capacity measurements and cell volume data are presented for a very magnesian glaucophane from a Tauern Window eclogite, which are combined with estimated entropy, thermal expansion, and compressibility data to generate an enthalpy of formation.
Abstract: New heat capacity measurements and cell volume data are presented for a very magnesian glaucophane from a Tauern Window eclogite. These data are combined with estimated entropy, thermal expansion, and compressibility data to generate an enthalpy of formation for glaucophane from experimentally determined phase equilibria. The data are supported by preliminary experiments of the author and provide consistent calculations on the pressure of formation of the Tauern eclogites and on the position of the blueschist-greenschist transformation reaction as studied experimentally by Maruyama et al. (1986). The resulting thermodynamic data for glaucophane may be combined with the dataset of Holland and Powell (1985) to calculate phase relations for blueschists and eclogites. The stability of magnesian glaucophane lies in the pressure range between 8 and 32 kbars at 400° C and between 13 and 33 kbars at 600° C, and the unusual eclogite assemblage of glaucophane+kyanite from the Tauern Window is restricted to pressures above 20 kbars at high water activity.
68 citations
TL;DR: In this paper, a C°° metric is constructed on a surface of revolution whose geodesic flow has positive measure entropy, which is defined by Wojtkowski's invariant cone field technique, and almost every point has a nonzero Lyapunov exponent.
Abstract: A C°° metric is constructed on S whose geodesic flow has positive measure entropy. By the uniformization theorem, we can induce a metric of constant negative curvature on the sphere minus three points. Each deleted point gives rise to a cusp going to infinity, which we cut off at some finite point and replace in a smooth way with a cap formed from a surface of revolution. The cap that we use has the property that a diverging family of geodesies that enters the cap will focus once while in the cap and then again be diverging when leaving the cap. The Clairaut integral of motion on a surface of revolution helps us to design this cap. Using Wojtkowski's invariant cone-field technique, we show that almost every point has a non-zero Lyapunov exponent. Positive entropy then follows by Pesin's formula. Our construction can be applied to surfaces of any genus yielding similar results. 0. Introduction On a compact surface M of negative curvature, the geodesic flow behaves stochastically. The original results in this field go back to Hedlund and Hopf, who showed, respectively, that the flow has dense orbits and is ergodic. A geodesic is determined by a point and direction, so the geodesic flow g, occurs in the unit tangent bundle SM, and a dense orbit comes arbitrarily close to every point and direction. Ergodicity is meant relative to the invariant Liouville measure /u.. These results are only applicable to surfaces of genus g ^ 2 since, by the Gauss-Bonnet theorem, the average curvature over the surface equals 2ir(2-2g). Do there exist metrics on the sphere, g = 0, and torus, g = 1, for which the geodesic flow behaves stochastically? On the standard sphere, the geodesies are given by the great circles and are all periodic. On the flat torus, K = 0, the direction of a geodesic stays constant, the flow is an integrable system and SM decomposes into invariant tori. Under small perturbations of the flat metric, the K.A.M. theory asserts that some of the invariant tori continue to exist, so the system remains non-ergodic. In this paper, we show that the sphere and torus can be given smooth metrics for which the geodesic flow has positive measure entropy. Positive entropy does not imply ergodicity. Rather, by results of Pesin [16], it implies that the system has components of positive measure on which the flow is ergodic and on which it exhibits the very strongest stochastic behaviour.
67 citations
TL;DR: In this article, the dimensionless number Πs describing the local entropy in a quenched flame is found to be Π s∼(Ped0)−2, where s = s l 2 k, l = α S u 0 (a characteristic length), k thermal conductivity, α thermal diffusivity, Su0 the adiabatic laminar flame speed at the unburned gas temperature, Pe d 0 = S u0 D α the flame Peclet number, and D the quench distance.
61 citations
01 Jan 1988
TL;DR: In this paper, the optimal T-S diagrams for magnetic refrigerators using Carnot, Ericsson and Brayton cycles were determined and compared to results of thermodynamic numerical models.
Abstract: Magnetic refrigeration utilizes the temperature dependent entropy change produced in a ferromagnetic or paramagnetic material when subjected to a change in magnetic field. By blending different materials together the temperature-entropy (T-S) behavior of the refrigerant may be tailored to maximize system performance. Optimal T-S diagrams for magnetic refrigerators using Carnot, Ericsson and Brayton cycles were determined and compared to results of thermodynamic numerical models.
47 citations
01 Jan 1988
TL;DR: In this article, the authors introduce the leafwise geodesic flow of a foliation, a flow on the unit tangent bundle to the leaves which preserves the natural foliation on this manifold.
Abstract: We introduce the leafwise geodesic flow of a foliation, a flow on the unit tangent bundle to the leaves which preserves the natural foliation on this manifold. The transverse dynamics of this flow closely mirror the dynamics of the original foliation, and in this paper we outline a program for the study of foliation dynamics based on this observation. For example, the topological entropy of a foliation is defined to be the toplogical entropy of this flow relative to the invariant foliation. This yields a topological entropy close to that defined by Ghys-Langevin-Walczak. The metric entropies of a foliation are defined to be the corresponding relative metric entropies of the leafwise geodesic flow, with respect to invariant measures for the flow. The topological entropy then dominates the metric entropies, and the supremum of the metric entropies over the space of probability measures equals the topological entropy. This extends to foliations the relative variational principle of Ledrappier and Walters. Upper estimates of foliation metric entropies via transverse Lyapunov exponents are given, extending work of Strelcyn, from which we deduce a generalization of a theorem of Sacksteder concerning the existence of linearly contracting holonomy in exceptional minimal sets for codimension-one foliations of differentiability class Holder C1.
22 citations
TL;DR: In this paper, explicit expressions for configurational contributions to the thermodynamics in the disordered phase are given for estimating the parameters of the H-H interactions from experimental data, and a model is suggested which relates this anomaly to a change of the electronic state of hydrogen in an alloy at x approximately xs.
Abstract: Earlier methods for the description of alloys with strong interatomic correlations are used to study H-H interactions and the thermodynamical properties of hydrogen in systems of the NbHx type. Explicit expressions are given for configurational contributions to the thermodynamics in the disordered phase. These expressions are used to estimate the parameters of the H-H interactions from experimental data. It has been found that in the vicinity of some x=xs approximately=0.6 the concentration dependence of the partial enthalpy of hydrogen in NbHx changes sharply. A model is suggested which relates this anomaly to a change of the electronic state of hydrogen in an alloy at x approximately xs. The calculations of the thermodynamical properties suggest a significant value of the configurational heat capacity Cconf and its strong dependence on x and T, as well as a considerable temperature dependence of the partial enthalpy and entropy of hydrogen, hH and sH.
17 citations
TL;DR: The entropy for a Markovian process is obtained and then applied to closed queueing network models of FMSs to discuss loading flexibility which arises from the power to regulate the frequency of the visit of a part to different work stations.
Abstract: An information-theoretic approach is applied for measuring the flexibility in flexible manufacturing systems (FMSs). The general relation between flexibility and entropy is discussed. The entropy for a Markovian process is obtained and then applied to closed queueing network models of FMSs to discuss loading flexibility which arises from the power to regulate the frequency of the visit of a part to different work stations. The concept of operations entropy as a measure of operations flexibility, which arises from the power to choose the work station and the corresponding operations, is introduced. The operations entropy has been decomposed into entropies within and between operations and entropies within and between groups of operations. This measure has been used to determine the next operation to be performed on a part by using the principle of least reduction of flexibility.
17 citations
TL;DR: In this article, an equivalence relation on the family of ground states and generalization of the Peierls and Pirogov-Sinai theory of phase transitions to systems with residual entropy was introduced.
Abstract: We introduce an equivalence relation on the family of ground states and generalize the Peierls and Pirogov-Sinai theory of phase transitions to systems with residual entropy. The idea consists in the replacement of the periodic ground states by equivalence classes together with an entropy factor. We apply these results to discuss the phase diagrams of diluted spin-1/2 systems.
TL;DR: In this article, the authors show that extended thermodynamics is in agreement with the kinetic theory of gases, and conciliate objectivity and the kinetic theories by using the technique of extended irreversible thermodynamics, which elevates the heat flux and the pressure tensor.
01 Sep 1988
TL;DR: In this paper, the authors present a new implementation of simulated annealing based on finite time thermodynamics and use ensembles over the entire configuration space to compute thermodynamic averages.
Abstract: We present a new implementation of simulated annealing. It calculates its own cooling schedule from thermodynamic information computed enroute. Our schedule proceeds at constant “thermodynamic speed” to minimize the entropy produced along the way. It is based on finite time thermodynamics and is, in some sense, optimal. We use ensembles over the entire configuration space to compute thermodynamic averages. Ensembles provide good statistics for the thermodynamic process as well as a direct, instantaneous measures of the nature of the configuration space with Hamming distances. We compare our implementation with some others on a random graph problem. It is found to produce superior results.
TL;DR: In this paper, the analogy between electric and thermal quantities is examined and it is seen that dimensional inconsistencies are overcome by the use of entropy instead of quantity of heat, although the results obtained do not confirm this.
Journal Article•
01 Jan 1988
TL;DR: In this paper, the thermodynamics of irreversible processes can be included into Lagrange-formalism and a methodical unification of thermodynamics, continuum mechanics and electromagnetism of matter may be obtained.
Abstract: Thermodynamics of irreversible processes can be included into Lagrange-formalism. Along the line of this formalism a methodical unification of thermodynamics, continuum mechanics and electromagnetism of matter may be obtained. The latter two topics have already been subsumed into Lagrange-formalism in the past.
TL;DR: In this paper, the authors measured the entropy of solution by gas-liquid chromatography for the alkanes from pentane to decane in dibutyl phthalate solution.
Abstract: The entropy of solution was measured by gas-liquid chromatography for the alkanes from pentane to decane in dibutyl phthalate solution. The results are discussed in relation to the Wertz-type equation, which correlates the entropy of solution with the thermodynamic third-law entropy of the solute, and to the scaled particle theory. A scaled particle treatment assuming non-spheres(spherocylinders) is shown to give improved results and to be promising in reproducing the experimental values of the entropy of solution, whereas the same treatment of spheres failed to explain the trend in the experimental values.
14 Nov 1988
TL;DR: Using these definitions, two algorithms are formulated and implemented with the help of its co-occurrence matrix and their superiority for image thresholding (object-background classification) is established.
Abstract: Entropy of order q (depending on the information contained in a sequence of gray levels of length q) and conditional entropy of an image are defined. Using these definitions, two algorithms are formulated and implemented with the help of its co-occurrence matrix. Their superiority for image thresholding (object-background classification) is established. >
TL;DR: This paper drew attention to a series of misconceptions and misstatements regarding the origin and meaning of some of the most basic concepts of engineering thermodynamics, such as reversibility, entropy, mechanical equivalent of the calorie, the first law of thermodynamics for open systems, enthalpy and the Diesel cycle.
TL;DR: In this article, specific heat and thermal expansion data of UPt 3 were analyzed by means of Gruneisen relations over a wide temperature range, and two contributions to both quantities were distinguished: a heavy-fermion contribution with a large value of 73 for the corresponding Grunisen parameter and an associated entropy of R In 2, and a second contribution that is dominated by photons.
TL;DR: In this paper, the Stratonovitch-Hubbard transformation of nickel was considered and the role of interband exchange interaction was studied in detail, and it was shown that the Curie temperature is reduced in comparison with the models without interband interactions.
TL;DR: In this article, the entropy production, conservation laws, and linear constituative equations that describe the irreversible behavior of polydisperse fluids near equilibrium are presented, and the problems of computing transport coefficients and solving the hydrodynamic equations are discussed.
Abstract: The entropy production, conservation laws, and linear constituative equations that describe the irreversible behavior of polydisperse fluids near equilibrium are presented. The problems of computing transport coefficients and solving the hydrodynamic equations are discussed.
TL;DR: In this paper, it was shown that if one neglects quantum fluctuations, the Fokker-Planck equation of AOB satisfies the conditions of detailed belancing, and then drew a parallel between the potential function contained in the stationary solution of this equation and the Gibbs' free energy in equilibrium thermodynamics.
TL;DR: In this article, the authors define global measures of uncertainty in the framework of Dempster-Shafer's Theory of Evidence, starting from the concepts of entropy and specificity introduced by Yager.
Abstract: The aim of this paper is to define global measures of uncertainty in the framework of Dempster-Shafer's Theory of Evidence. Starting from the concepts of entropy and specificity introduced by Yager, two measures are considered; the lower entropy and the upper ent
TL;DR: In this article, a closed-thermosiphon type cold neutron source (CNS) was considered on the basis of non-equilibrium thermodynamics, and a discontinuous thermodynamic model consisting of two large sub-systems connected by a small transport sub system was employed.
Abstract: A fundamental consideration of a closed-thermosiphon type cold neutron source (CNS) has been presented on the basis of the non-equilibrium thermodynamics. In order to simplify the treatment, a discontinuous thermodynamic model consisting of two large sub-systems connected by a small transport sub-system is employed. The analyses are especially concentrated in the self-regulation property, that is, the amount of liquid hydrogen in the moderator cell can be kept almost constant against thermal disturbances from reactor output fluctuations. It is shown that this property results from a thermodynamic process producing an entropy of a total system by a temperature increment in which an evaporation in one sub-system is compensated by a liquefaction in the other sub-system linked together by a common quantity of latent heat.