Hasil untuk "Thermodynamics"

Chao Luo, Jialin Yuan, Hun Lin et al.

Characterizing full-scale pore-throat systems constitutes a critical challenge in the investigation of hydrocarbon-bearing spaces within tight unconventional reservoirs. Given the intricate nature of micro–nano-scale pore throats, individual characterization techniques are insufficient to achieve a comprehensive and precise description. In response, this study develops a Gaussian Mixture Model (GMM)-oriented methodology for full-scale pore-throat analysis integrating multi-source data, which encompasses five successive procedures: data optimization, optimal cluster number determination, model analysis, data fusion, and data reconstruction. Taking tight mixed-lithology samples from Block D of the Qaidam Basin as the research object, effective pore-throat thresholds were defined based on lithology-dependent breakdown pressures to facilitate cluster analysis of multi-source datasets. Following the screening of representative pore-throat clusters and data fusion via Gaussian Mixture functions, the full-scale pore-throat distribution was ultimately derived. Comparative analysis demonstrates that Nuclear Magnetic Resonance (NMR) and High-Pressure Mercury Intrusion (HPMI) data exhibit satisfactory fitting consistency at major cluster peaks, with NMR being more effective in resolving nanopores and HPMI excelling in characterizing medium to large pores. Comprehensive evaluation results validate that the proposed methodology enables efficient integration of multi-technical data, uncovers hidden pore-throat systems, and realizes innovative fractal dimension analysis of full-scale pore-throat structures by taking pore-throat clusters as the basic analytical unit. Consequently, this work offers a novel methodological framework for the quantitative characterization of full-scale pore-throats using multi-source data.

Gui-Lin She, Lei-Lei Gan

This study investigates the combined resonance phenomenon in magneto-electro-elastic (MEE) cylindrical shells under longitudinal and lateral excitations with thermal factors, addressing the complex interaction between mechanical, electrical, and magnetic fields in smart structures. The research aims to establish a theoretical framework for predicting resonance behaviors in energy harvesting and sensing applications. Using Maxwell’s equations and Hamilton’s principle, the governing equations for combined resonance are derived. The method of varying amplitude (MVA) is employed to acquire the combined resonance response across varying parameters. Furthermore, the Runge–Kutta method is applied to investigate the bifurcation and chaotic motion characteristics under different longitudinal and lateral excitation conditions. Key findings reveal the coupling effects of multi-physical fields on resonance frequencies, demonstrating quantitative agreement with prior studies. The results provide fundamental insights into the dynamic characteristics of MEE materials, offering theoretical support for optimizing their performance in adaptive engineering systems.

Edward Bormashenko

“Thermodynamics is only physical theory of universal content, which I am convinced will never be overthrown, within the framework of applicability of its basic concepts [...]

Pavlos Nikolaidis

Global efforts aiming to shift towards renewable energy and smart grid configurations require accurate unit commitment schedules to guarantee power balance and ensure feasible operation under different complex constraints. Intelligent systems utilizing hybrid and high-level techniques have arisen as promising solutions to provide optimum exploration–exploitation trade-offs at the expense of computational complexity. To ameliorate this requirement, which is extremely expensive in non-interconnected renewable systems, radically different approaches based on enhanced priority schemes and Boolean encoding/decoding have to take place. This compilation encompasses various mappings that convert multi-valued clausal forms into Boolean expressions with equivalent satisfiability. Avoiding any need to introduce prior parameter settings, the solution utilizes state-of-the-art advancements in the field of artificial intelligence models, namely Boolean mapping. It allows for the efficient identification of the optimal configuration of a non-convex system with binary and discontinuous dynamics in the fewest possible trials, providing impressive performance. In this way, Boolean mapping becomes capable of providing global optimum solutions to unit commitment utilizing fully tractable procedures without deteriorating the computational time. The results, considering a non-interconnected power system, show that the proposed model based on artificial intelligence presents advantageous performance in terms of generating cost and complexity. This is particularly important in isolated networks, where even a-not-so great deviation between production and consumption may reflect as a major disturbance in terms of frequency and voltage.

Maja Ivanovski, Darko Goričanec, Danijela Urbancl

In this work, the thermochemical properties of municipal solid waste (MSW) are studied using the torrefaction process as the main method for investigation. Torrefaction experiments were carried out using an electric laboratory furnace, at temperatures of 200, 250, and 300 °C. The residence time was set to 90 min. Proximate and ultimate analysis were performed on the torrefied MSW samples and compared with the properties of the raw MSW samples. In addition, the thermal properties of the obtained torrefied MSW samples were evaluated by thermogravimetric analysis (TGA) and derivative thermogravimetric analysis (DTG). The following could be stated: the obtained results showed that mass and energy yields (MY and EY, respectively) decrease with increasing when torrefaction temperature, while the heating values (HHV) increased under the same conditions (from 24.3 to 25.1 MJ/kg). Elemental analysis showed an increase in carbon content (C), from 45.7 ± 0.9 to 52.8 ± 1.05 wt.%, and decrease in oxygen content (O), from 45.6 ± 0.9 to 39.5 ± 0.8 wt.%, when torrefaction temperature is increased, which is consistent with the general definition of the torrefaction process. In addition, enhancement factors (EFs) and fuel ratios (FRs) were calculated, which ranged from 1.00 to 1.02 and 0.16 to 0.23, respectively. Some anomalies were observed during the thermal analysis, which are assumed to be related to the composition of the selected MSW. This study therefore shows that torrefaction pretreatment can improve the physicochemical properties of raw MSW to a level comparable to coal, and could contribute to a better understanding of the conversion of MSW into a valuable, solid biofuel.

Yuening Zhang, Xujin Qin, Xuefeng Zhu et al.

Unravelling the mechanism of chirality transfer in supramolecular assemblies is important to understand the relationship between molecular chirality and supramolecular chirality. Here, the authors use nonlinear spectroscopy and molecular dynamic simulations to study the long-range chirality transfer in a self-assembled supramolecular system.

Ülker Aslı Güler, Fuat Özyonar, Mehmet Kobya

In this investigation is aimed at the removal of Astrazon Blue FGRL (AB FGRL) (basic dye) from an aqueous solution using waste clay (MC) obtained from the gold mine area. The natural clay was characterized and identified using X-ray diffraction (XRD) analysis.Then, the contact time, adsorbent dosage, pH, initial dye concentration and temperature experiments were carried out in a batch system. The removal efficiency was found to be 97% at pH 7, 80 min, 30oC, 4 g/L MC dosage, 50 mg/L initial dye concentration. The adsorption data are applied to the Langmuir, Freundlich, and Temkin isotherm models. The maximum capacity of waste mine clay (MC) was found to be 191.75 mg/g. The pseudo-second-order kinetic models and Elovich kinetic model were used to examine the adsorption process of Astrazon Blue FGRL. The results of kinetic experiments were defined by the pseudo-second-order model point out a chemisorption reaction. The adsorption thermodynamics were investigated using parameters such as enthalpy change (∆Ho), Gibbs free energy change (∆Go) as well as entropy change (∆So). These calculations reveal that sorption of Astrozon Blue FGRL is endothermic, spontaneous and enthalpy driven. This work provides guidance for using of waste clay materials for applications in the adsorption removal of dye from aqueous solution.

Momal Akram, Muhammad Salman, Rabia Rehman et al.

A novel biosorbent, Haplophragma adenophyllum (HAB) was employed to explore the biosorption mechanism of Gentian Violet (GV) dye. The novel sorbent was characterized by using FTIR spectra and physiochemical analysis. The effect of different optimizing factors like HAB dosage, GV initial concentration, contact time between sorbent and sorbate, pH of a solution, and the temperature was studied. The optimum removal of GV by HAB was observed at pH 6.0. The equilibrium study was carried out using Langmuir and Freundlich isotherms. Experimental data fitted well in Langmuir isotherm indicating monolayer isotherm with qmax value obtained at optimum process condition of 13.21 mg/g. Kinetics study was carried out and followed by pseudo-second-order model. Thermodynamics studies reveal the endothermic reaction.

Muhammad Zia Ullah Khan, Bilal Akbar, Ramisha Sajjad et al.

The ability of controlling the temperature of a system by using heat transfer and thermodynamics-based technology is known as thermal management. Thermal management is a crucial problem which is to be addressed in the various fields. This study accompanies a numerical work to provide a solution for heat transfer enhancement by studying a straight rectangular cross-section channel. The selected channel is used with and without disturbance in the form of dimple-protrusion with circular & through geometry. Water is employed as the base fluid for identifying flow behavior and heat carrying capacity while the heat flux is applied as a boundary condition. Furthermore, using the same boundary condition, copper oxide nanoparticles with the concentration of 0.10%, 0.15% and 0.20% respectively are added in the channels. Flow conditions are varied from 100 to 900 considering the laminar regime with fully developed flow. Performance enhancement criteria are evaluated by considering the Nusselt number, friction factor, and base cooling. The fully developed velocity profile is maintained at the inlet of test section for all Reynolds numbers. Semi-Implicit Method for Pressure Linked Equations (SIMPLE) pressure-velocity coupling is used with the second-order upwind scheme for discretization and solution approximation. It is observed that circular dimple-protrusion channel is effective for high Reynolds numbers and through dimple protrusion is efficient for intermediate Reynolds numbers. 10% improvement in Nusselt number is observed for circular dimple-protrusion channel with 0.2% CuO concentration by comparing the results of dimple-protrusion channel with straight channel at same nanoparticle concentration. Compared to straight channel with 0% and 6% particles concentration 5% and 7% increase in Stanton number is observed for through disruption case. Dimple channel on the other hand showed 3% and 5% increase. Furthermore, the formation of vortices at high Reynolds number is observed in circular dimple-protrusion channel.

Gaelle Lebrun, Feishi Xu, Claude Le Men et al.

The influence of viscosity and surface tension on oxygen transfer was investigated using planar laser-induced fluorescence with inhibition (PLIF-I). The surface tension and the viscosity were modified using Triton X-100 and polyacrylamide, respectively. Changes in the hydrodynamic parameters of millimetric bubbles were identified, and transfer parameters were calculated. The results revealed a decrease in the mass transferred in the presence of a contaminant. For modified viscosity, the decrease in mass transferred was allowed for by current correlations, but the presence of surfactant led to a sharp decrease in the liquid side mass transfer coefficient, which became even lower when polymer was added. An explanation for the gap between classical correlations and experimental values of k_L is discussed, and a hypothesis of the existence of an accumulation of contaminant in the diffusion layer is proposed. This led to the possibility of a decrease in the diffusion coefficient and oxygen saturation concentration in the liquid film, explaining the discrepancy between models and experience. Adapted values of D_O2 and [O₂] * in this layer were estimated. This original study unravels the complexity of mass transfer from an air bubble in a complex medium.

Javier de Andrés de Vicente

Resumen La introducción del concepto de entropía en la arquitectura permite entender el profundo vínculo que hay entre la degradación de la energía y la degradación de la materia, bifurcando la atención hacia el consumo diario de energía de un edificio a lo largo de su vida y hacia el coste energético que implica levantar —o reparar— la propia construcción. En definitiva, dos enfoques para entender el impacto de la construcción sobre el medio. El primero, nos habla de aquella arquitectura que utiliza las energías libres que proceden del aprovechamiento de las variables climáticas como herramientas de diseño. El segundo se refiere a esa arquitectura que, en sus distintas variantes, recupera el patrimonio construido. La reflexión que aquí se plantea pasa por hibridar ambos enfoques de entender el impacto de la construcción sobre el medio, aproximándose a la intervención sobre el patrimonio construido a partir del empleo de principios termodinámicos. Para ello, se apoya en el análisis de dos intervenciones contemporáneas consideradas como paradigmáticas que operan sobre piezas del patrimonio industrial transformándolas para usos culturales. A diferencia de los habituales criterios de intervención basados principalmente en el léxico, el contexto o el programa, estas obras reflejan una forma de recuperar el patrimonio desde premisas de diseño fundamentadas en intercambios de energía con la atmósfera del entorno próximo y abiertas al cambio. Ambas, en cierto modo, son una forma de entender la arquitectura como esa “dialéctica del cambio entrópico” de la que hablaba Robert Smithson. Así, desde un dualismo material y conceptual que aúna presente y pasado, energía y memoria, ambas intervenciones generan imágenes memorables. En última instancia, su estética, basada en el ensamblaje, la hibridación y la contraposición, tanto a nivel energético como material y formal, busca hacer visibles las tensiones y dificultades inherentes al paso del tiempo por arquitecturas pasadas. Abstract The introduction of the concept of entropy in architecture has brought to light the tight bond that exists between the degradation of energy and the degradation of matter, shifting the focus to the daily energy consumption of a building during its lifespan, as well as to the cost, in energy terms, of constructing —or repairing— that particular building. In short, it has given way to two different approaches to understanding the impact of construction on the environment. The first approach refers to the kind of architecture that uses free energies generated from an efficient use of climate variables as a design tool. The second approach refers to the kind of architecture that, in its different variants, chooses to restore built heritage. The purpose of this article is to hybridise these two approaches to the impact of construction on the environment by examining architectural intervention on built heritage through the lens of thermodynamic principles. To this end we will review two contemporary interventions that have paradigmatically transformed old industrial buildings into new cultural premises. Far from applying standard intervention criteria, largely based on architectural language, context or programme, these restoration works follow design premises that are founded on energy exchanges with the neighbouring environment, and that are open to change. In a way, both exemplify how architecture can be understood as a “dialectics of entropic change”, as coined by Robert Smithson. From a stance of material and conceptual dualism that blurs the lines between past and present, energy and memory, both interventions generate memorable images. Their outward appearance, based on assemblage, hybridisation and contrast, both in terms of energy, form and matter, ultimately seeks to showcase the tensions and challenges inherent to the passing of time in architecture.

B. Pourhassan

Abstract In this paper, higher order quantum gravity effects on the thermodynamics of Hořava–Lifshitz black hole investigated. Both Kehagius–Sfetsos and Lu–Mei–Pop solutions of Hořava–Lifshitz black hole considered and higher order corrected thermodynamics quantities obtained. The first order correction is logarithmic and second order correction considered proportional to the inverse of entropy. These corrections are due to the thermal fluctuation and interpreted as quantum loop corrections. Effect of such quantum corrections on the stability and critical points of Horava–Lifshitz black holes studied. We find that higher order correction affects critical point and stability of Lu–Mei–Pop solution and yield to the second order phase transition for the case of Kehagius–Sfetsos solution.

Mir Hameeda, Behnam Pourhassan, Mir Faizal et al.

Abstract In this paper, we analyze the clustering of galaxies using a modified theory of gravity, in which the field content of general relativity has been be increased. This increasing in the field content of general relativity changes the large distance behavior of the theory, and in weak field approximation, it will also modify the large distance behavior of Newtonian potential. So, we will analyzing the clustering of multi-component system of galaxies interacting through this modified Newtonian potential. We will obtain the partition function for this multi-component system, and study the thermodynamics of this system. So, we will analyze the effects of the large distance modification to the Newtonian potential on Helmholtz free energy, internal energy, entropy, pressure and chemical potential of this system. We obtain also the modified distribution function and the modified clustering parameter for this system, and hence observe the effect of large distance modification of Newtonian potential on clustering of galaxies.

Anna Paula Littig Berger, Rodrigo de Oliveira Pezzin, Felipe Fardin Grillo et al.

Steel desulfurization mixtures of the CaO-Al2O3 system are the most industrially used. These mixtures require an amount of solid CaO to keep them always saturated in CaO. The aim of this paper is to study the influence of adding CaF2 and Na2O on the desulfurization efficiency of CaO-Al2O3 system mixtures. Desulfurizing steel mixtures capable of producing steels with sulfur content of less than 0.0020% were formulated. Desulfurizing mixtures based on CaO-Al2O3-flux were prepared with fluxes CaF2 and Na2O. All mixtures presented 95% of liquid phase and 5% of solid CaO, which, according to the literature, are the most efficient slags of this system. The equilibrium conditions were simulated using the composition of the mixtures and the steel by means of computational thermodynamic software. In these simulations, the activities of the slag components, the percentage of solids and liquids, the slag viscosity, and the equilibrium sulfur content were determined. The experimental tests were carried out in an induction furnace at 1600 °C. In addition, data on sulfide capacity (Cs), sulfur partition (Ls) and optical basicity (ʌ) of the initial mixtures, were calculated. The results of the simulations show that all mixtures have thermodynamic potential to reach the target of sulfur content set for this work. The mixtures with CaF2 proved to be the most efficient. However, it is possible to obtain sulfur contents of 0.0020% using mixtures without CaF2. Keywords: Steel desulfurization, CaO-Al2O3mixtures, Addition of CaF2and Na2O, Computational thermodynamics

Simone Salvadori, Mauro Carnevale, Alessia Fanciulli et al.

In transonic high-pressure turbine stages, oblique shocks originating from vane trailing edges impact the suction side of each adjacent vane. High-pressure vanes are cooled to tolerate the combustor exit-temperature levels, then it is highly probable that shock impingement will occur in proximity to a row of cooling holes. The presence of such a shock, together with the inevitable manufacturing deviations, alters the location of the shock impingement and of the performance parameters of each cooling hole. The present work provides a general description of the aero-thermal field that occurs on the rear suction side of a cooled vane. Computational Fluid Dynamics (CFD) is used to evaluate the deterministic response of the selected configurations in terms of adiabatic effectiveness, discharge coefficient, blowing ratio, density ratio, and momentum ratio. Turbulence is modelled by using both the Shear Stress Transport method (SST) and the Reynolds Stress Model (RSM) implemented in ANSYS<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>&#174;</mo> </msup> </semantics> </math> </inline-formula> FLUENT<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>&#174;</mo> </msup> </semantics> </math> </inline-formula>. The obtained results are compared with the experimental data obtained by the Institut f&#252;r Thermische Str&#246;mungsmaschinen in Karlsruhe. Two uncertainty quantification methodologies based on Hermite polynomials and Pad&#232;&#8722;Legendre approximants are used to consider the probability distribution of the geometrical parameters and to evaluate the response surfaces for the system response quantities. Trailing-edge and cooling-hole diameters have been considered to be aleatory unknowns. Uncertainty quantification analysis allows for the assessment of the mutual effects on global and local parameters of the cooling device. Obtained results demonstrate that most of the parameters are independent by the variation of the aleatory unknowns while the standard deviation of the blowing ratio associated with the hole diameter uncertainty is around <inline-formula> <math display="inline"> <semantics> <mrow> <mn>12</mn> <mo>%</mo> </mrow> </semantics> </math> </inline-formula>, with no impact by the trailing-edge thickness. No relevant advantages are found using either SST model or RSM in combination with Hermite polynomials and Pad&#232;&#8722;Legendre approximants.

Francisco-José Rubio-Hernández

Rheology of a concrete is mainly controlled by the rheological behavior of its cement paste. This is the main practical reason for the extensive research activity observed during 70 years in this research subfield. In this brief review, some areas of the research on the rheological behavior of fresh cement pastes (mixture method influence, microstructure analysis, mineral additions influence, chemical additives influence, blended cements behavior, viscoelastic behavior, flow models, and flow behavior analysis with alternative methods) are examined.

Mohsen Abbaszadeh, Seyed M. Shariatipour

CO2 injection into geological formations is considered one way of mitigating the increasing levels of carbon dioxide concentrations in the atmosphere and its effect on and global warming. In regard to sequestering carbon underground, different countries have conducted projects at commercial scale or pilot scale and some have plans to develop potential storage geological formations for carbon dioxide storage. In this study, pure CO2 injection is examined on a model with the properties of bunter sandstone and then sensitivity analyses were conducted for some of the fluid, rock and injection parameters. The results of this study show that the extent to which CO2 has been convected in the porous media in the reservoir plays a vital role in improving the CO2 dissolution in brine and safety of its long term storage. We conclude that heterogeneous permeability plays a crucial role on the saturation distribution and can increase or decrease the amount of dissolved CO2 in water around &plusmn; 7% after the injection stops and up to 13% after 120 years. Furthermore, the value of absolute permeability controls the effect of the Kv/Kh ratio on the CO2 dissolution in brine. In other words, as the value of vertical and horizontal permeability decreases (i.e., tight reservoirs) the impact of Kv/Kh ratio on the dissolved CO2 in brine becomes more prominent. Additionally, reservoir engineering parameters, such as well location, injection rate and scenarios, also have a high impact on the amount of dissolved CO2 and can change the dissolution up to 26%, 100% and 5.5%, respectively.

Alessandro Bravetti, Christine Gruber, Cesar S. Lopez-Monsalvo et al.

Motivated by black holes thermodynamics, we consider the zeroth law of thermodynamics for systems whose entropy is a quasi-homogeneous function of the extensive variables. We show that the generalized Gibbs–Duhem identity and the Maxwell construction for phase coexistence based on the standard zeroth law are incompatible in this case. We argue that the generalized Gibbs–Duhem identity suggests a revision of the zeroth law which in turns permits to reconsider Maxwell's construction in analogy with the standard case. The physical feasibility of our proposal is considered in the particular case of black holes.

Pierre Labastie, R. Whetten

R. T. Ross