Thermodynamics

Performance Analysis of an Ejector Enhanced Pressure Gain Combustion Gas Turbine

by Chris Ward

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, Nashville, Tennessee, Jan. 9-12, 2012, AIAA-2012-772

A Thermodynamic Comparison of Arboreal and Terrestrial Sleeping Sites for Dry-Habitat Chimpanzees (Pan troglodytes schweinfurthii) at the Toro-Semliki Wildlife Reserve, Uganda

by David Samson

Co-authored with Kevin Hunt

The nightly construction of an arboreal sleeping platform (SP) has been observed among every chimpanzee's population... more The nightly construction of an arboreal sleeping platform (SP) has been observed among every chimpanzee's population studied to date. Here, we report on bioclimatic aspects of SP site choice among dry-habitat chimpanzees (Pan troglodytes schweinfurthii) at the Toro-Semliki Wildlife Reserve, Uganda. We placed a portable weather monitor within 1 m of chimpanzee SPs and compared the microenvironment of this site with terrestrial monitors placed 10 cm above the ground directly underneath the simultaneously studied SP. We calculated physical “comfort levels” of monitored sites using the RayMan thermophysiological model that we modified to take ape body proportions into account. The RayMan tool gauges energy balance using wind speed, temperature, relative humidity, and heat index in conjunction with the study subject's mass and stature to determine whether the individual is in energy balance or homeostasis. We found that (1) terrestrial microclimates have greater homeostatic potential than arboreal microclimates, and (2) there is a significant positive linear relationship between wind speed and height of SP in the forest canopy. Advantages of terrestrial sites are that they require lesser energetic expenditure to stabilize the body when the SP is under construction and perhaps during use as well. We found that terrestrial sites also had better homeostatic potentials. This combination of advantages explains why SPs are so often sited terrestrially in habitats where predation risk is low. Early hominins must have had technological or social measures to avoid or deter predators that were significantly advanced over those found among chimpanzees before they began sleeping on the ground.

The Thermodynamics of Neoliberalism

by Blair Fix

This paper uses a synthesis of world-systems and ecological economics to investigate the transition between the... more This paper uses a synthesis of world-systems and ecological economics to investigate the transition between the post-WWII boom and the ensuing neoliberal era. Using insights from social metabolism, the world economy is treated as "dissipative structure" which does "useful work" on itself in order to maintain and/or grow social metabolism. The Marxian notion of "surplus rate" is equated to the yearly growth rate in useful work production. The goal of this paper is to show that the neoliberal era can be treated as the confluence of two separate phenomena: 1) a global energy stagnation caused by oil depletion; 2) a shift in economic hegemony, due to declining “efficiency returns on investment” in core regions. Lastly, this paper proposes that neoliberal era wage stagnation can be attributed to a corresponding “thermodynamic” labour productivity stagnation.

Sorting Stable vs Unstable Hypothetical Compounds: The Case of Multi-Functional ABX Half-Heusler Filled Tetrahedral Structures

by Andriy Zakutayev

Advanced Functional Materials 22, 1425 (2012)

Thermodynamic Insights on the Structure and Energetics of s-Triphenyltriazine

by Carlos Lima

Carlos F. R. A. C. Lima, Jose C. S. Costa, and Luís M. N. B. F. Santos; J. Phys. Chem. A, 2011, 115, 9249.

For s-triphenyltriazine, at T = 298.15 K, were measured the standard (p0 = 105 Pa) molar enthalpy of combustion, by... more For s-triphenyltriazine, at T = 298.15 K, were measured the standard (p0 = 105 Pa) molar enthalpy of combustion, by static bomb combustion calorimetry, and the standard molar enthalpy, entropy, and Gibbs energy of sublimation by Knudsen/Quartz crystal effusion. A comparison between the entropies of sublimation of s-triphenyltriazine and the isosteric 1,3,5-triphenylbenzene gave a good indication that the higher symmetry of the former contributes significantly to the decrease of its volatility. A computational study at the MP2/cc-pVDZ and B3LYP/6-311++g(d,p) levels of theory was carried out in order to obtain the gas phase geometry, enthalpy, and barriers to internal rotation about the phenyl-triazine bonds. Making use of homodesmotic reaction schemes, a marked stabilization was observed in the molecule of s-triphenyltriazine relative to analogous systems. This result is supported both experimentally and computationally and, combined with a detailed analysis of the literature data concerning the energetics and structure of related compounds, pointed to a significant enthalpic stabilization associated with the exchange of an intramolecular Ar
H---H
Ar close contact by an Ar
H---N(Ar) one. An inspection of the ring
ring torsional profiles in azabenzenes and biphenyls, obtained computationally at the SCS-MP2/cc-pVDZ level, showed that the ring
ring torsions are the dimensions of the potential energy surface (PES) that chiefly determine the energetic differentiation in this class of compounds.

Phase Stability Trend in Linear α-Polythiophene Oligomers

by Carlos Lima

José C.S. Costa, Carlos F.R.A.C. Lima, Lígia R. Gomes, Bernd Schroder, and Luís M.N.B.F. Santos;
J. Phys. Chem. C 2011, 115, 23543–23551.

This work reports a thermodynamic study and structural analysis of a series of linear α-oligothiophenes to explore the... more This work reports a thermodynamic study and structural analysis of a series of linear α-oligothiophenes to explore the effect of the successive increase of the number of thiophene rings on the thermodynamic properties related to solid-liquid and solid-gas equilibria. The compounds studied were α-quaterthiophene (α-4T), α-quinquethiophene (α-5T), and α-sexithiophene (α-6T). For each compound, the vapor pressures at different temperatures were measured using the Knudsen effusion method combined with a quartz crystal microbalance (KMBQ). From the obtained results, the standard molar enthalpies, entropies and Gibbs energies of sublimation were determined. For α-4T and α-5T (α-6T decomposes), the fusion temperatures and the standard molar enthalpies of fusion were determined in a power compensated differential scanning calorimeter (DSC). Standard molar entropies of fusion were derived accordingly. The obtained results for sublimation and fusion were compared with available data for the analogous thiophene (T), 2,2'-bitiophene (α-2T) and 2,2':5',2''-terthiophene (α-3T) compounds. To support the energetic study, a structural analysis was performed, based on the available X-ray crystallographic data for solid phase, and computational chemistry calculations, using density functional theory (DFT) with the hybrid exchange correlation functional (B3LYP) at the 6-311++G(d,p) level of theory, for gas phase. Entropic and enthalpic differentiations along the linear α oligothiophenes series were observed suggesting a subtle odd-even effect and also a trend change in the series, centered at α-4T, which is probably related with the change in the supramolecular structure.

Structural and Thermodynamic Characterization of Polyphenylbenzenes

by Carlos Lima

Carlos F. R. A. C. Lima, Marisa A. A. Rocha, Andre Melo, Lígia R. Gomes, John N. Low, and Luís M. N. B. F. Santos;
J. Phys. Chem. A, 115, 11876-11888.

The thermodynamic and structural study of a series of polyphenylbenzenes, from benzene, n(Ph) = 0, to... more The thermodynamic and structural study of a series of polyphenylbenzenes, from benzene, n(Ph) = 0, to hexaphenylbenzene, n(Ph) = 6, is presented. The available literature data for this group of compounds was extended by the determination of the relevant thermodynamic properties for 1,2,4-triphenylbenzene, 1,2,4,5-tetraphenylbenzene, and hexaphenylbenzene, as well as structural determination by X-ray crystallography for some of the studied compounds. Gas phase energetics in this class of compounds was analyzed from the derived standard molar enthalpies of formation in the gaseous phase. The torsional profiles relative to the phenyl
phenyl hindered rotations in some selected polyphenylbenzenes, as well as the gas phase structures and energetics, were derived from quantum chemical calculations. In the ideal gas phase, a significant enthalpic destabilization was observed in hexaphenylbenzene relative to the other polyphenylbenzenes, due to steric crowding between the six phenyl substituents. A relatively low enthalpy of sublimation was observed for hexaphenylbenzene, in agreement with the decreased surface area able to establish intermolecular interactions. The apparently anomalous low entropy of sublimation observed for hexaphenylbenzene is explained by its high molecular symmetry and the six highly hindered phenyl internal rotations. For the series of polyphenylbenzenes considered, it was shown that the differentiation in the entropy of sublimation can be chiefly ascribed to the torsional freedom of the phenyl substituents in the gas phase and the entropy terms related with molecular symmetry.

Phenylnaphthalenes: Sublimation Equilibrium, Conjugation, and Aromatic Interactions

by Carlos Lima

Carlos F. R. A. C. Lima, Marisa A. A. Rocha, Bernd Schröder, Lígia R. Gomes, John N. Low, and Luís M. N. B. F. Santos;
J. Phys. Chem. B 2012, 116, 3557−3570.

In this work, the interplay between structure and energetics in some representative phenylnaphthalenes is discussed... more In this work, the interplay between structure and energetics in some representative phenylnaphthalenes is discussed from an experimental and theoretical perspective. For the compounds studied, the standard molar enthalpies, entropies and Gibbs energies of sublimation, at T = 298.15 K, were determined by the measurement of the vapor pressures as a function of T, using a Knudsen/quartz crystal effusion apparatus. The standard molar enthalpies of formation in the crystalline state were determined by static bomb combustion calorimetry. From these results, the standard molar enthalpies of formation in the gaseous phase were derived and, altogether with computational chemistry at the B3LYP/6-311++G(d,p) and MP2/cc-pVDZ levels of theory, used to deduce the relative molecular stabilities in various phenylnaphthalenes. X-ray crystallographic structures were obtained for some selected compounds in order to provide structural insights, and relate them to energetics. The thermodynamic quantities for sublimation suggest that molecular symmetry and torsional freedom are major factors affecting entropic differentiation in these molecules, and that cohesive forces are significantly influenced by molecular surface area. The global results obtained support the lack of significant conjugation between aromatic moieties in the α position of naphthalene but indicate the existence of significant electron delocalization when the aromatic groups are in the β position. Evidence for the existence of a quasi T-shaped intramolecular aromatic interaction between the two outer phenyl rings in 1,8-
di([1,1′-biphenyl]-4-yl)naphthalene was found, and the enthalpy of this interaction quantified on pure experimental grounds as −(11.9 ± 4.8) kJ·mol−1, in excellent agreement with the literature CCSD(T) theoretical results for the benzene dimer.

Comment on "Geometrothermodynamics of a Charged Black Hole of String Theory"

by Cesar S Lopez-Monsalvo

Co-authored with Francisco Nettel and Alberto Sanches. To appear in Brazilian Journal of Physics.

We comment on the conclusions found by Larra\~naga and Mojica regarding the consistency of the Geoemtrothermodynamics... more We comment on the conclusions found by Larra\~naga and Mojica regarding the consistency of the Geoemtrothermodynamics programme to describe the critical behaviour of a Gibbons-Maeda-Garfinkle-Horowitz-Strominger charged black hole. We argue that making the appropriate choice of metric for the thermodynamic phase space and, most importantly, considering the homogeneity of the thermodynamic potential we obtain consistent results for such a black hole.

Thermodynamics and Human Activity

by Adam Goodwin

Draft paper prepared for conference presentation

The ‘solutions’ offered to ‘correct’ the current financial ‘crisis’ are entirely consistent with the economic world... more The ‘solutions’ offered to ‘correct’ the current financial ‘crisis’ are entirely consistent with the economic world view (Lawson 1997; Mäki [ed.] 2001), insofar as they are grounded in thinking that is fundamentally disconnected from the physical and social reality of the world that surrounds us. The real crisis for humanity has three converging and interrelated fronts, which Shiva (2008) identifies as climate, food and energy. However, the common denominator among all of these fronts is the assumption of easily accessible and abundant fossil fuel, particularly oil. The learned extraction and myriad uses of hydrocarbon fuels has infused our species’ interaction with our environment with unprecedented amounts of surplus energy. In this thermodynamic sense, modernity becomes merely a by-product of the hyper-energized activities of humans within their environment. Further, in line with this thermodynamic understanding, I argue this massive energy infusion into our species has been conserved—manifesting in other forms, including, most pertinent to the present crisis, human thought. Since the Industrial Revolution, increasingly energized human thought has produced countless theoretical abstractions mapping the natural world and, more problematically, the social world. It is the theoretical abstractions regarding the social world, particularly the idea of the state and the market, which have prompted our species to neglect our intuitive sense of the Laws of Thermodynamics and form social systems that actually work in contradiction to these Universal Laws. However, the energy surplus required to think in such absurd abstract terms seems to be disappearing accompanying the depletion of world oil reserves past the point of no return—Global Peak Oil. The full consequences of oil depletion for society seem unknowable; however, the energy-intensive practices involved in governance (protection) of the state and market will, eventually, no longer be tenable. The consequences of oil depletion for the individual are clear: the oil depletion crisis will vindicate the Anarchist principles of direct action, personal responsibility and mutual aid through the individual steps required to overcome the impending artificially-induced hyper-scarcity of centralized food and energy distribution schemes.

Is Gravity an Entropic Force?

by Shan Gao

Entropy special issue “Black Hole Thermodynamics”, Jacob D. Bekenstein (eds). 13, 936-948 (2011).

The remarkable connections between gravity and thermodynamics seem to imply that gravity is not fundamental but... more The remarkable connections between gravity and thermodynamics seem to imply that gravity is not fundamental but emergent, and in particular, as Verlinde suggested, gravity is probably an entropic force. In this paper, we will argue that the idea of gravity as an entropic force is debatable. It is shown that there is no convincing analogy between gravity and entropic force in Verlinde’s example. Neither holographic screen nor test particle satisfies all requirements for the existence of entropic force in a thermodynamics system. Furthermore, we show that the entropy increase of the screen is not caused by its statistical tendency to increase entropy as required by the existence of entropic force, but in fact caused by gravity. Therefore, Verlinde’s argument for the entropic origin of gravity is problematic. In addition, we argue that the existence of a minimum size of spacetime, together with the Heisenberg uncertainty principle in quantum theory, may imply the fundamental existence of gravity as a geometric property of spacetime. This may provide a further support for the conclusion that gravity is not an entropic force.

Applicability of equations of state for modeling helium systems

by Rohan Dutta

Rijo Jacob Thomas, Rohan Dutta,  Parthasarathi Ghosh, Kanchan Chowdhury
Cryogenic Engineering Centre, Indian Institute of Technology Kharagpur, India, 721302
Cryogenics
Available online 10 March 2012

Proper design of helium systems with large number of components and involved configurations such as helium... more Proper design of helium systems with large number of components and involved configurations such as helium liquefiers/refrigerators requires the use of tools like process simulators. The accuracy of the simulation results, to a great extent, depends on the accuracy of property data. For computation of thermodynamic properties of helium, the 32-parameter MBWR equation of state proposed by R.D. McCarty and V.D. Arp, 1990 is widely used. However, it is computationally involved, makes the simulation process more time-consuming and sometimes leads to computational difficulties such as numerical oscillations, divergence in solution especially, when the process operates over a wide thermodynamic region and is constituted of many components. Substituting MBWR EOS by simpler equations of state (EOS(s)) at selected thermodynamic planes, where the simpler EOS(s) have the similar accuracy as that of MBWR EOS may enhance ease of computation. In the present paper, the methodology to implement this concept has been elucidated with examples of steady state and dynamic simulation of helium liquefier/refrigerator based on Collins cycle. The above concept can be applied to thermodynamic analysis of other process cycles where computation of fluid property is involved.

Information-theoretic bound on the energy cost of stochastic simulation

by Mile Gu

Life in time: The missing temporal dimension in autopoiesis (Abstract)

by Ezequiel Di Paolo

Di Paolo, E. (2008). Life in time: the missing temporal dimension in autopoiesis (abstract). In S. Bullock, J. Noble, R. Watson, and M. A. Bedau (eds.) Artificial Life XI: Proceedings of the Eleventh International Conference on the Simulation and Synthesis of Living Systems, p. 761. MIT Press, Cambridge, MA.

Imperialism Old & New: A Thermodynamic Analysis

by Blair Fix

This paper examines historical instances of imperialism using a world systems perspective grounded in thermodynamics. This paper examines historical instances of imperialism using a world systems perspective grounded in thermodynamics.

Story, Play, and Steam: Thermoludic Narratology in Video Game Studies

by Jameson Hogan

For completion of the MA in Literature and Rhetoric/Composition.

This project examined the often competing perspectives of ludology and narratology in the field of video game studies,... more This project examined the often competing perspectives of ludology and narratology in the field of video game studies, and attempts to incorporate both into a model of game narrative engagement based on the laws of thermodynamics. Further, this project sought to demonstrate that the same model can be used to examine the study of traditional literary texts.

The Assassin's Creed video game series served as the video game text under examination, and the novel House of Leaves as the literary.

A novel approach for the estimation of soil ground heat flux

by Zhihua Wang

Agricultural and Forest Meteorology, 154-155: 214-221, 2012

Most conventional numerical schemes for soil ground heat flux estimation rely on the knowledge of the temporal... more Most conventional numerical schemes for soil ground heat flux estimation rely on the knowledge of the temporal evolution of soil temperature. Here we propose and test a novel scheme, which requires no information on soil temperatures to supplement the flux plate measurement. The proposed method is based on the fundamental solution of the one-dimensional heat equation and Duhamel’s principle for the incorporation of inhomogeneous boundary conditions. Being completely independent of the soil temperature, the new scheme therefore avoids a potential source of error in measurements and in heat storage calculation. The only thermal property involved in the new scheme is the thermal diffusivity of the soil, which is a weak function of soil water content and can be approximated as constant with reasonable accuracy. For validation, the proposed method is compared to the conventional approach using a canonical one-dimensional heat conduction problem, as well as real field measurements. Results of comparison highlight that the new model is robust and capable of preserving the good accuracy of the conventional approach with reduced input information. In addition, the effect of inclusion of the heat storage term in the ground heat flux is evaluated in the context of surface energy balance closure for field measurements.

Thermal aspects of a shipboard integrated electric power system

by Christopher Holsonback

Knudsen effusion mass spectrometric approach to the thermodynamics of Na2O–Nb2O5 system

by Jurij Koruza

Co-authored with A. Popovič, L. Bencze, B. Malič and M. Kosec;

Published in "International Journal of Mass Spectrometry"

Knudsen effusion mass spectrometry (KEMS) was used to determine the equilibrium vapour pressures of sodium over five... more Knudsen effusion mass spectrometry (KEMS) was used to determine the equilibrium vapour pressures of sodium over five selected compositions in different solid two-phase regions of the Na2O–Nb2O5 system at 1100–1470 K. The results were then used to determine the standard thermodynamic functions (ΔfGT°,   ΔfH298 K°,   ST°) of five solid compounds: Na3NbO4, NaNbO3, Na2Nb4O11, NaNb3O8 and NaNb13O33. These data were then incorporated into the IVTANTHERMO database to perform equilibrium calculations under real conditions relevant to the high temperature stability of sodium niobate, which is an important end member of the alkali niobate-based lead-free piezoelectric ceramics.

Experimental studies on the fatigue life of shape memory alloy bars

by Sara Casciati

Casciati S. and Marzi A. (2010). “Experimental studies on the fatigue life of shape memory alloy bars”. Smart Structures and Systems, 6(1), 73-85. ISSN: 1738-1584.

DATE AND PLACE OF PUBLICATION: January 2010; Techno-Press, Daejeon 305-600, South Korea.

ABSTRACT: The potential offered by the thermo-mechanical properties of shape memory alloys (SMA) in structural... more ABSTRACT: The potential offered by the thermo-mechanical properties of shape memory alloys (SMA) in structural engineering applications has been the topic of many research studies during the last two decades. The main issues concern the long-term predictability of the material behaviour and the fatigue lifetime of the macro structural elements (as different from the one of wire segments). The laboratory tests reported in this paper are carried out on bar specimens and they were planned in order to pursue two objectives. First, the creep phenomenon is investigated for two different alloys, a classical Ni-Ti alloy and a Cu-based alloy. The attention is then focused on the Cu-based alloy only and its fatigue characteristics at given temperatures are investigated. Stress and thermal cycles are alternated to detect any path dependency.

KEYWORDS: creep; fatigue; hysteresis; shape memory alloys; thermo-mechanics; viscosity.