bluuebunny/crossref_metadata_2025_split huggingface dataset:
Entropy: Part I — Statistics and its Misleading Disorder
Authors: Gyftopoulos Elias P. 
Published: December 2021

Abstract
The overwhelming majority of scientists, engineers, and other professionals believe that: (a) statistical mechanics explains thermodynamics, and provides explicit expressions of entropy (for example, S = k ln Ω); and (b) in general, each entropy represents disorder in a system and, in particular for given values of energy, volume, and amounts of constituents, the largest value of the entropy represents the ultimate disorder (thermodynamic equilibrium state). The purposes of this paper are to present both theoretical and experimental evidence that refutes these beliefs and to show that the spontaneous increase in thermodynamic entropy represents a nonstatistical, natural tendency to perfect order rather than disorder. The arguments are presented in two parts. Brief discussions of the premises and conclusions of the statistical interpretation of thermodynamics, the association of the statistical entropy with disorder, and inconsistencies that arise from such an association are presented in Part I. A nonstatistical exposition of thermodynamics, the interpretation of entropy as a measure of the quantum-theoretic shape of molecules, and the association of the entropy of classical thermodynamics with perfect order are presented in Part II.
Modeling of Incomplete Equilibria in Industrial and Environmental Systems and Processes: A Theoretical Framework
Authors: Filippov Sergei P. , Kaganovich Boris M. , Yablonsky Gregory S. 
Published: December 2021

Abstract
The paper presents the models of the regions of thermodynamic accessibility and incomplete equilibria in physico-chemical systems that are intended to study diverse industrial and environmental processes. The models are compared with the traditional ones of classical equilibrium thermodynamics. Peculiarities of the presented mathematical problems are analyzed and the ways for devising relevant algorithms are outlined. The gains of the approach suggested are discussed.
Fuel Processing and Combustion: An Extreme Thermodynamic Analysis
Authors: Filippov Sergei P. , Keiko Alexandre V. , Pavlov Peter P. 
Published: December 2021

Abstract
The paper concerns application of the extreme thermodynamics approach within the analysis of chemically reacting systems. Some principal techniques of the approach are shown on simplified examples of coal processing and nitrogen oxides formation. The analyses are based on the investigation of incomplete chemical equilibria using the models of extreme intermediate states (MEIS). The close correspondence between the MEIS statement and graphical interpretations is shown and used.
Trade-Off Design Analysis of Operating Pressure and Temperature in PEM Fuel Cell Systems
Authors: Barbir Frano , Balasubramanian Bhaskar , Neutzler Jay 
Published: December 2021

Abstract
The paper presents the results of an optimization study of an automotive fuel cell propulsion system equipped with a fuel reformer. Based on a set of fuel cell polarization curves determined experimentally by running a prototype fuel cell stack at a variety of operating pressures and temperatures, a numerical steady state model was used to determine the optimal operating pressure and temperature. The optimization criteria were the size of individual components and the entire propulsion system as well as its total efficiency at both full power and partial load. The results suggested that an automotive system should be operated at relatively high pressure (308 kPa), but an expander must be used to recover most of the power used for compression. A surprising result of this analysis is that a relatively low temperature (∼60°C) results in smallest heat rejection equipment if neutral water balance is mandated. The efficiency of the system is about 33% at full power and about 38% at 25% of the load. Higher efficiencies may be achieved by selecting a higher fuel cell operating voltage, but that would result in larger fuel cell stacks, which may be a limiting factor for automotive application with the state-of-the-art fuel cells.
On-Particle EDS Analysis of PtRu/C DMFC Catalysts Using High-Resolution TEM
Authors: Boxall Deborah L. , Lukehart Charles M. , Kenik Edward A. 
Published: December 2021

Abstract
On-particle energy dispersive x-ray spectroscopy (EDS) was performed on direct methanol fuel cell (DMFC) anode catalysts in order to measure the Pt:Ru ratio of individual catalyst particles in Pt1Ru1/C and Pt3Ru1/C composite materials. It was found that the Pt:Ru ratio increased as the diameter of the particles decreased. The curvature observed in the plots of the integrated intensities of the two metals is consistent with loss of Ru from the surface of the metal particle. Compensation for this Ru loss computationally results in a Pt:Ru ratio that is within experimental error of the targeted alloy composition.
Analysis of a Large Scale Liquid Hydrogen Dispersion Using the Multi-Phase Hydrodynamics Analysis Code (CHAMPAGNE)
Authors: Chitose K. , Takeno K. , Okamoto M. , Hayashi K. , Hishida M. 
Published: December 2021

Abstract
It is planned to use hydrogen extensively as a source of clean energy in the next century. As part of our investigation for an International Clean Energy Network Using Hydrogen Conversion (WE-NET), we have been studying to establish a safety scheme to ensure that both existing and new hydrogen technologies are implemented without endangering public safety. In this plan, we consider the transport and storage of a large quantity of hydrogen in a large tank. First we must evaluate the consequence of the postulated accident of liquid hydrogen. Since we have developed the multi-phase hydrodynamics analysis code (CHAMPAGNE), we apply the code to simulate the formation and dispersion of hydrogen vapor clouds.
In the present paper we have improved the calculation model in two ways. We added a function to CHAMPANGE for solving evaporation phenomena realistically, made many parametric calculations and planned the small-scale hydrogen dispersion experiments for the validation of this model. Another improvement is the turbulent mixing of evaporated liquid hydrogen.
Now we have completed the basic functions of our simulation code. And these models of CHAMPANGE code must be verified by the experimental data.
Improvement of the Exergoeconomic “Fuel-Impact” Analysis for Acceptance Tests in Power Plants
Authors: Zaleta-Aguilar Alejandro , Gallegos-Muñoz Armando , Valero Antonio , Royo Javier 
Published: December 2021

Abstract
This work builds on the previous work on “Exergoeconomics Fuel-Impact” developed by Torres (1991), Valero et. al. (1994), and compares it with respect to the Performance Test Code (PTC’s) actually applied in power plants (ASME/ANSI PTC-6, 1970). With the objective of proposing procedures for PTC’s in power plant’s based on an exergoeconomics point of view. It was necessary to validate the Fuel-Impact Theories, and improve the conceptual expression, in order to make it more applicable to the real conditions in the plant. By mean of a program using simulation and field data, it was possible to validate and compare the procedures. This work has analyzed an example of a 110 MW Power Plant, in which all the exergetic costs have been determined for the steam cycle, and a fuel-impact analysis has been developed for the steam turbines at the design and off-design conditions. The result of the fuel-impact analysis is compared with respect to a classical procedure related in ASME-PTC-6.
Exergetic and Thermoeconomic Analyses of a Combined Cycle Plant
Authors: Kim Duck-Jin , Jeon Jin-Seok , Kwak Ho-Young 
Published: December 2021

Abstract
Exergetic and thermoeconomic analyses were performed for a 500-MW combined cycle plant systematically. In this analysis, the mass and energy conservation laws were strictly applied to each component of the system. Careful attention was also paid to the quantitative balances of the exergy and exergetic cost for each component as well as the whole system. The exergoeconomic model employed provided, which is self-consistent the productive structure of the system considered, consequently could visualize the cost formation process and the productive interaction between components clearly. The computer program developed in this study may apply to determine the production cost of any power plant such as gas turbine and gas-turbine cogeneration systems and to study the thermodynamic performance and the sensitivity of such plants to changes in process and/or component design variables.
A Thermodynamic Approach for Conceptual Design of Chemical Processes
Authors: Sorin M. , Hammache A. , Diallo O. 
Published: December 2021

Abstract
The purpose of this paper is to develop a new thermodynamic approach for conceptual design of chemical processes. The approach is based on a concept of reducible superstructure and exergy load distribution analysis. It starts by building a specific reducible structure of the process flowsheet called the “competitive process” superstructure. A two-step exergy analysis is carried out on the superstructure to reduce it to a final optimal flowsheet topology. In the first step, only the design options with the highest impact on the utilizable exergy coefficient of the overall flowsheet is kept for subsequent analysis. In the next step, the distribution of exergy loads from the less efficient units to the more efficient ones makes it possible to relocate the units inside the flowsheet. The new approach was applied for the design of a gas separation section within a benzene synthesis chemical plant. It has been found that the overall exergy efficiency of the benzene synthesis is highest with the design option using a membrane for hydrogen recuperation and an absorber for benzene recuperation. The final step is the relocation of the absorber achieved through the application of the exergy load distribution analysis. Compared with the previous solutions obtained by the hierarchic and mathematical approaches, a new flowsheet for benzene synthesis has been proposed. It consumes the least amount of raw materials, such as hydrogen and toluene, and produces the least amount of discharged gas as waste.
A Simulation Code for Single Phase Geothermal Fields
Authors: Maria Francesco Di , Desideri Umberto 
Published: December 2021

Abstract
This paper presents a design and off-design study of a geothermal field consisting of a number of wells, a steam network which collects the geothermal fluid, and a power plant to generate electricity. The geothermal field considered is located in Italy and the fluid is a mixture of steam and non-condensable gases. The power plant is a conventional type for vapor dominated fields and has a compressor-extractor to remove non-condensable gases from the condenser. The condenser has wet cooling towers to remove heat.
In this study, computer codes developed at the University of Perugia were used to simulate the behavior of geothermal field as a whole. The wells are modeled with second order functions in order to describe pressure-flow rate and temperature-flow rate correlations. The geothermal fluid network is calculated by setting pressures and thermal losses in all the branches. The power plant is simulated with all its components: steam turbine, condenser, gas extractor, cooling towers and auxiliaries. All the components of the geothermal field are simulated at both design and off-design conditions.
The fluid network is solved with an algorithm developed by the authors, which allows the definition of boundary conditions by means of curves based on experimental data. The advantage in comparison with conventional techniques, requiring a fixed pressure or flow rate as boundary condition, is that the solution of the network and the power plant is always a real solution.
The results show how changes in ambient conditions or in the characteristic curve of one or more plant components may influence power production and the exploitation of the geothermal source.
Preliminary Thermodynamics of a Practical Hot Air Power System With Isothermal Combustion and Expansion
Authors: Fineblum Solomon S. 
Published: December 2021

Abstract
The potential benefits of external combustion hot air engines: quietness, combustion cleanliness and combustion efficiency, as well as multi-fuel usage, can be realized only if the heat of the combustion gases is efficiently transferred into the working fluid. Heat transfer in external combustion power systems is usually accomplished by a single, relatively large heat exchanger and by a large delta T across the heat exchanger, which leads to poor First and Second Law efficiencies. The basic flaw in the conventional analysis of externally heated power cycles is identified. A novel open cycle external combustion power system described here incorporates constant pressure recuperation and isothermal expansion for power generation, as in a classical Ericsson cycle. The cycle is improved by the use of exhaust heated isothermal combustion and heat transfer into an immediately adjacent isothermally heated expander. Isothermal expansion is compared with adiabatic expansion. It is shown that a fixed value of specific work can be produced at a lower expander inlet temperature with isothermal expansion than with adiabatic expansion. The thermodynamic as well as practical advantages of this lower temperature are noted. The cycle efficiency is shown to be further improved by isothermal combustion. A practical embodiment of the proposed power system in the form of a hot air turbine will be described. Engine performance, in terms of specific power and system efficiency as a function of temperature and expansion ratio, is predicted with realistic assumptions of component efficiencies and system losses.
The Impact of Reference Environment Selection on the Exergy Efficiencies of Aerospace Engines
Authors: Etele Jason , Rosen Marc A. 
Published: December 2021

Abstract
An exergy analysis is applied to a turbojet engine over a range of flight altitudes ranging from sea level to 15,000 m (∼50,000 ft), to examine the effects of using different reference-environment models. The results of this analysis using a variable reference environment (equal to the operating environment at all times) are compared to the results obtained using two constant reference environments (sea level and 15,000 m). The actual rational efficiency of the turbojet decreases with increasing altitude, ranging from a value of 16.9% at sea level to 15.3% at 15,000 m. In the most extreme cases considered, the rational efficiency value calculated using a constant reference environment varies by approximately 2% from the variable reference environment value.
“Life-Time Oriented” Design and Operation of Energy Conversion Plants: Criteria and Procedures
Authors: Lazzaretto Andrea , Macor Alarico , Mirandola Alberto , Stoppato Anna 
Published: December 2021

Abstract
The design, operation, control and diagnosis of energy conversion systems are different aspects of an integrated approach, which considers the whole life-time of the plants and brings about different skills:
- applied thermodynamics and its various methods of analysis and assessment of functional performances;
- machine design, stress analysis and mechanical control of components, to assess their health state and expected durability;
- diagnosis methods, to check the departures from the expected performances and identify their causes;
- economics, in both designing the plant and deciding if and when it is advisable to do maintenance or an overhaul on machines to restore them to expected performance.
Different methods, procedures and techniques are discussed here, in order to select the most suitable approach to the “life time oriented” design and operation. The following base points have been identified and are presented in this paper:
- to implement efficient operation models of the plants and employ suitable computer codes able to simulate the nameplate and off-design operation as well as to check the consistency of the data coming from the measurement systems;
- to apply the traditional first-law analysis for preliminary thermodynamic calculations and on-line checks;
- to use the exergetic and exergoeconomic analyses to obtain further and more valuable results, both in the design of the plants and during their operation as well as in the diagnosis of departures from the reference values of the parameters (due to malfunctions or change in boundary conditions).
Some results coming from the application of these procedures to a cogenerative plant are shown.
Performance Characteristics of a Combined Ejector-Absorption Heat Pump Using NH3-H2O
Authors: Kouremenos D. A. , Rogdakis E. D. , Alexis G. K. 
Published: December 2021

Abstract
Absorption system have been investigated for many years. However, coefficient of performance COP or heat gain factor HGF for absorption systems are significantly lower than those for conventional compression systems. This has restricted their wide application.
This paper discusses the behavior of mixture NH3-H2O through of an ejector, operating in an absorption heat pump system. This combination improves the performance of conventional absorption system and with the phasing out of ozone-damaging refrigerants, absorption refrigerators, heat pumps and air-conditioning now provide a potential alternative.
For the detailed calculation of the proposed system a method has been developed, which employs analytical functions describing the thermodynamic properties of die mixture. The influence of three major parameters: generator, condenser and evaporator temperature, on ejector efficiency and heat gain factor of the system is discussed.
Also the maximum value of HGF was estimated by correlation of above three temperatures.
Localization of One-Dimensional Thermoelastic Waves in Layered Structures
Authors: Cetinkaya Cetin , Li Chen 
Published: December 2021

Abstract
Including the second sound effect, a transfer matrix formulation based on the generalized dynamical theory of thermoelasticity is developed for longitudinal wave component propagation in a thermoelastic layer. The attenuation and propagation properties of one-dimensional thermoelastic wave in both continuum and layered structures are studied using this formulation and the periodic systems framework. Localization of thermal waves is demonstrated in the time-spacial domain by an FFT-based transient analysis. A perturbation analysis tor identifying leading terms in thermal attenuation is performed, and the role of the thermal elastic coupling term in attenuation is determined. The reflection and transmission coefficients between half-spaces are calculated to evaluate the potential practical use of the approach in laser-based nondestructive testing.
Ultrasonic Signals Generated by a Laser Source in Film/Substrate Systems
Authors: Murray T. W. , Guo Z. , Krishnaswamy S. , Achenbach J. D. 
Published: December 2021

Abstract
A model for the pulsed laser generation of ultrasound in an isotropic film on a semi-infinite substrate is presented. The model gives the time domain displacement of the system as a function of the density and mechanical properties of the film and substrate and the thermal properties of the film. Theoretical signals are calculated and analyzed for both a slow layer on a fast substrate and a fast layer on a slow substrate. The model has been verified experimentally using a 1 ns Nd:YAG laser source for acoustic wave generation and a stabilized Michelson interferometer for detection. Experimental and theoretical signals agree well for both fast on slow and slow on fast systems.
Guided Waves in Thin-Walled Structural Members
Authors: Rogers J. B. C. , Zhuang W. , Shah A. H. , Popplewell N. 
Published: December 2021

Abstract
Infrastructures are deteriorating and billions of dollars are spent to rehabilitate them. Civil structures usually comprise of pavements and bridge decks (plates), pipelines (cylinders), and structural members having, say, I, L, etc. cross sections. The deterioration of these structures causes flaws arising from factors such as the severity of the weather, aging, corrosion, fatigue cracks, etc... The flaws degrade the stiffness (material properties) of a structure and severe conditions eventually can result in a catastrophic failure. Thus, the detection and characterization of the flaws is important in evaluating and monitoring the integrity of existing structures and determining the viability of their continued use or a change in use. Therefore, it is necessary to employ a reliable and effective, quantitative nondestructive evaluation (QNDE) to characterize the mechanical properties and identify defects in the structures. Ultrasonic waves provide such a technique but a knowledge of guided elastic waves is required. Considerable information is available for waves in plates and cylinders but very little work has been reported in the literature on the waves in thin-walled, structural members.
In this paper, a semi-analytical finite element (SAFE) formulation is proposed to study the wave propagation characteristics of thin-walled members. Common structural members are considered as an assemblage of thin plates. The members are assumed to be infinitely long in the longitudinal (axial) direction. The ratio of the thickness of the plate to the wavelength in the axial direction is assumed to be small so that the plane-stress assumption is valid. Employing a finite element modeling in the transverse direction circumvents difficulties associated with the cross-sectional profile of the member. The dynamic behavior is approximated by dividing the plates into several line (one-dimensional) segments and representing the generalized displacement distribution through the segment by polynomial interpolation functions. By applying Hamilton’s principle, the dispersion equationis obtained as a standard algebraic eigenvalue problem. The accuracy of the proposed method is demonstrated by comparing the results with analytical solutions. Detailed numerical results are presented for an I shaped cross section.
Variable Frequency Microwaves (VFM) for Non-Destructive Testing and Evaluation of Adhesively Bonded Polymers
Authors: Siu F. , Siores E. , Basu A. 
Published: December 2021

Abstract
This paper presents a novel microwave assisted nondestructive evaluation system for industrial applications. The technique provides rapid, on-line, non-intrusive, non-destructive, and volumetric monitoring of adhesively bonded polymer materials. When a microwave signal of a given frequency is launched into a metallic cavity which is fully or partially filled with a material, the microwaves reflect back and forth between cavity walls and travel through the material many times until a final standing wave condition is established. Material property variables such as physical geometry, chemical and physical properties, internal or surface defects, and dielectric properties can contribute to its unique output characterisation. The established reflected and the input signals form a ratio, which can be monitored and plotted as a function of the frequency. The signal ratio versus frequency curve is called the microwave reflective spectrum. The spectrum generated can be used as a signature curve for assessing bond quality during processing. This way, the same material under the same processing environment provides a common characteristic curve, which can be traced. Therefore, the quality of adhesively bonded products can be detected by the intrinsic spectrum signals generated.