Hasil untuk "Thermodynamics"

Xiaoping Wang, Liqiang Liang, Qingsong Song et al.

Traditional fluid network theory often underestimates pressure losses in complex pipe-bundle systems operating under vortex-dominated flow conditions, with deviations exceeding 20% in many cases. To address this limitation, this study proposes a vortex-based correction method. Three-dimensional simulations were performed on a multidirectional parallel pipe bundle to analyze vortex formation and to quantify the effects of fluid properties (viscosity and inlet velocity) and structural parameters (branch diameter, manifold cross-sectional ratio, and manifold arrangement) on pressure loss. To account for vortex-induced energy dissipation that is overlooked by conventional one-dimensional network models, an additional vortex-induced loss coefficient, α, is introduced to modify the pressure-loss formulation. Results indicate that higher viscosity, larger branch diameter, a higher manifold cross-sectional ratio, and a co-flow arrangement improve flow uniformity and prediction accuracy. Conversely, higher inlet velocities and counter-flow arrangements intensify vortex effects and increase prediction deviations. Least-squares fitting indicates that α ranges from 1.15 to 1.37. Implementation of the proposed correction reduces pressure-loss prediction errors to within 5%, demonstrating the method’s effectiveness and extending the applicability of fluid network theory to vortex-dominated flows.

Shuaidong Wang, Fengyin Chen, Shenghui Yue et al.

Efficient and safe extraction of coalbed methane is essential for reshaping China’s energy composition. This study integrates CO₂ adsorption, N₂ adsorption, and corrected mercury intrusion porosimetry (MIP) data to analyze the full pore size distribution (PSD) of six coal samples from the Qinshui and Tiefa Basins. By applying multifractal theory, we identified key heterogeneity features across different coal ranks, followed by a discussion of the factors influencing these parameters. The results indicate the following: (1) Coal matrix compressibility significantly impacts MIP results when mercury intrusion pressure exceeds 10 MPa, with corrected mesopore and macropore volume reductions ranging from 59.85–96.31% and 3.11–15.53%, respectively. (2) Pore volume distribution varies with coal rank, as macropores dominate in low-rank coal, while micropores contribute most in medium- and high-rank coal, accounting for over 90% of the total specific surface area. Multifractal analysis of CO₂, N₂, and corrected MIP data confirms notable multifractal characteristics across the full pore size range. (3) As the degree of coalification increases, as indicated by the rise in the R_o,max value, there is a notable negative correlation observed among the multifractal parameters D_min-D₀, D₀-D_max, Δα, and H. A positive correlation exists between moisture content and volatile matter content with D_min-D₀, Δα, and H, while a significant negative correlation is shown between the concentration of minerals and D_min-D₀, Δα, and H. There exists a favorable correlation between inertinite concentration and D₀-D_max. This work presents a theoretical foundation and empirical proof for the secure and effective extraction of coalbed methane in the researched region.

Njabulo Mziwandile Zulu, Hamed Hashemi, Kaniki Tumba

Gas hydrate inhibition using chemicals has been under continuous investigation, and several modelling studies have been published since its inception. Since it is not always feasible to conduct experimental research, it is especially crucial to forecast the conditions under which gas hydrates may form and dissociate in the presence of chemical inhibitors. As a result, a reliable forecasting tool is vital. This article provides an exhaustive review of various modelling methodologies in the context of gas hydrate chemical inhibition. The key aspects of empirical models, thermodynamic models, kinetic models, artificial intelligence-based models and quantum chemistry-based models are presented. Critical analysis of each modelling approach has been performed, highlighting strengths, limitations, and areas where further investigations are still crucial. Rapid progress has been made with respect to gas hydrate modelling approaches in the context of chemical inhibition; however, further research is still vital to bridge the gaps that have been identified in this review. Potential improvements to existing models have been proposed, particularly in terms of integrating experimental data and utilizing hybrid approaches, which could serve as valuable future directions for the field.

Houda Taher Elhmali, Cristina Serpa, Vesna Radojevic et al.

The microstructure–property relationship in poly(methyl methacrylate) PMMA composites is very important for understanding interface phenomena and the future prediction of properties that further help in designing improved materials. In this research, field emission scanning electron microscopy (FESEM) images of denture PMMA composites with SrTiO₃, MnO₂ and SrTiO₃/MnO₂ were used for fractal reconstructions of particle agglomerates in the polymer matrix. Fractal analysis represents a valuable mathematical tool for the characterization of the microstructure and finding correlation between microstructural features and mechanical properties. Utilizing the mathematical affine fractal regression model, the <i>Fractal Real Finder</i> software was employed to reconstruct agglomerate shapes and estimate the Hausdorff dimensions (HD). Controlled energy impact and tensile tests were used to evaluate the mechanical performance of PMMA-MnO₂, PMMA-SrTiO₃ and PMMA-SrTiO₃/MnO₂ composites. It was determined that PMMA-SrTiO₃/MnO₂ had the highest total absorbed energy value (E_tot), corresponding to the lowest HD value of 1.03637 calculated for SrTiO₃/MnO₂ agglomerates. On the other hand, the highest HD value of 1.21521 was calculated for MnO₂ agglomerates, while the PMMA-MnO₂ showed the lowest E_tot. The linear correlation between the total absorbed impact energy of composites and the HD of the corresponding agglomerates was determined, with an R² value of 0.99486, showing the potential use of this approach in the optimization of composite materials’ microstructure–property relationship.

Ünal Çamdalı

Thermodynamics is the most basic energy science. It is derived from the words thermal (heat) and dynamic (motion). Although its laws have existed since the beginning of the universe, the development of thermodynamics as a science was with the invention of steam engines in England. These laws, as known, are the Zeroth, First, Second and Third Laws of Thermodynamics. These are four macro laws, and they were determined based on observation. They are not the product of theoretical thought. Zeroth Law reveals the basic structure of temperature measurement, based on the principle that if two different systems are in thermal equilibrium separately with a third system, there must be thermal equilibrium between them. The First and Second Laws are the fundamental laws regarding energy. The first law, also known as the law of conservation of energy, and the second law, also known as the law of entropy, along with explaining the principles of energy conversion; also make a significant contribution to understand the functioning mechanism of the universe. The Third Law states that as chemically homogeneous and perfectly crystalline substances approach absolute zero temperature (273 C, 0 K), their entropy (or entropy changes) will also approach zero; in other words, it states that there can be no disorder or movement in the substances in question at this temperature. It is also important that thermodynamics science has a wide range of applications, from technical fields to philosophy, therefore it is known by large masses. Because its laws are among the most fundamental laws of the universe, in other words it is universal. Laws are noteworthy for the establishment, operation and analysis of engineering and many other systems, as well as for understanding the order of the universe. Additionally, some cosmologists strive to explain the order and functioning mechanism of the universe by making use of the laws of thermodynamics. Moreover, the laws of thermodynamics also give clues about the existence of the universe. Entropy, defined based on the second law of thermodynamics, is a phenomenon that gives the numerical magnitude of the disorder or complexity of a system. The more disordered or complex a system is, the greater its irreversibility and entropy will be. There is also a structure of the law that affects every system everywhere in the universe. It is not dependent on time and space. Time and space are literally subject to this law. The law has been in effect since the beginning of the universe, and it will continue to exist if the universe exists. Because universe means system; system means mechanism; mechanism means a structure that works according to the sovereignty of laws. Energy is needed to sustain life. Even though energy is not destroyed, the use of resources means that they move from a certain potential to a dead state (environment) because of the law of entropy. This process is valid for all systems in the universe. While all energies are processed through this process, living creatures in nature experience a similar process as they move from life to death. Eventually, all energy sources in the universe will go to the environment and become dead. This situation can be described as the entropy apocalypse of the universe. The concept of the apocalypse also reflects chaotic conditions such as noise and turmoil. Sources state that a cosmically stagnant situation will occur before the apocalypse. This is the cosmic dead state of the universe. In this study, an attempt was made to establish a relationship between entropy and doomsday by using the laws of Thermodynamics. In this context, the fact that the end of the universe is similar to the point where the entropy apocalypse will occur, as expressed in the doomsday scenario in religious literature (including the Religion of Islam), is tried to be explained on the plane of science and religion.

Z. Q. Chen, Y. H. Shang, X. D. Liu et al.

Abstract Eutectic alloys have garnered significant attention due to their promising mechanical and physical properties, as well as their technological relevance. However, the discovery of eutectic compositionally complex alloys (ECCAs) (e.g. high entropy eutectic alloys) remains a formidable challenge in the vast and intricate compositional space, primarily due to the absence of readily available phase diagrams. To address this issue, we have developed an explainable machine learning (ML) framework that integrates conditional variational autoencoder (CVAE) and artificial neutral network (ANN) models, enabling direct generation of ECCAs. To overcome the prevalent problem of data imbalance encountered in data-driven ECCA design, we have incorporated thermodynamics-derived data descriptors and employed K-means clustering methods for effective data pre-processing. Leveraging our ML framework, we have successfully discovered dual- or even tri-phased ECCAs, spanning from quaternary to senary alloy systems, which have not been previously reported in the literature. These findings hold great promise and indicate that our ML framework can play a pivotal role in accelerating the discovery of technologically significant ECCAs.

Dragan Marković, Mihailo Čubrović

We analyze the time-dependent free energy functionals of the semiclassical one-dimensional Bose-Hubbard chain. We first review the weakly chaotic dynamics and the consequent early-time anomalous diffusion in the system. The anomalous diffusion is robust, appears with strictly quantized coefficients, and persists even for very long chains (more than hundred sites), crossing over to normal diffusion at late times. We identify fast (angle) and slow (action) variables and thus consider annealed and quenched partition functions, corresponding to fixing the actions and integrating over the actions, respectively. We observe the leading quantum effects in the annealed free energy, whereas the quenched energy is undefined in the thermodynamic limit, signaling the absence of thermodynamic equilibrium in the quenched regime. But already the leading correction away from the quenched regime reproduces the annealed partition function exactly. This encapsulates the fact that in both slow- and fast-chaos regime both the anomalous and the normal diffusion can be seen (though at different times).

Mikiyas Abewaa, Ashagrie Mengistu, Temesgen Takele et al.

Abstract The potential for malachite green dye saturated effluent to severely affect the environment and human health has prompted the search for effective treatment technologies. Thus, this study was conducted with the goal of developing activated carbon from Rumex abyssinicus for the adsorptive removal of malachite green dye from an aqueous solution. Unit operations such as drying, size reduction, impregnation with H3PO4, and thermal activation were used during the preparation of the activated carbon. An experiment was designed considering four main variables at their respective three levels: initial dye concentration (50, 100, and 150 mg/L), pH (3, 6, and 9), contact period (20, 40, and 60 min), and adsorbent dosage (0.05, 0.01, and 0.15 g/100 mL). Optimization of the batch adsorption process was carried out using the Response Surface methodology's Box Behnken approach. The characterization of the activated carbon was described by SEM for surface morphology with cracks and highly porous morphology, FTIR for multi-functional groups O–H at 3506.74 cm−1 and 3290.70 cm−1, carbonyl group stretching from aldehyde and ketone (1900–1700 cm−1), stretching motion of aromatic ring C=C (1543.12 cm−1), stretching motion of –C–H (1500–1200 cm−1), vibrational and stretching motion of –OH (1250.79 cm−1), and vibrational motion of C–O–C (1049.32 cm−1), pHpzc of 5.1, BET for the specific surface area of 962.3 m2/g, and XRD for the presence of amorphous structure. The maximum and minimum dye removal efficiencies of 99.9% and 62.4% were observed at their respective experimental conditions of (100 mg/L, 0.10 mg/100 mL, pH 6, and 40 min) and (100 mg/L, 0.15 mg/100 mL, pH 3, and 20 min), respectively. Langmuir, Freundlich, Toth, and Koble-Corrigan models were used to evaluate the experimental data, in which Koble-Corrigan model was found to be the best fit with the highest value of R2 0.998. In addition to this, the kinetic studies were undertaken using pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Boyd models, and as a result, the pseudo-second-order model proved to have a better fit among the kinetic models. The kinetics and isotherm analysis revealed that the nature of the adsorption to be homogenous and monolayer surfaces driven by chemosorption. Furthermore, the thermodynamics study revealed the nature of adsorption to be feasible, spontaneous, and endothermic. On the other hand, the reusability study depicted the fact that the adsorbent can be utilized for five cycles with a negligible drop in the removal efficiencies from 99.9 to 95.2%. Finally, the low-cost, environmentally benign, and high adsorption capacity of the adsorbent material derived from Rumex abyssinicus stem could be used to treat industrial effluents.

Ahmed A. Al Ghafli, Ramsha Shafqat, Azmat Ullah Khan Niazi et al.

This paper is concerned with the existence of a mild solution for the fractional delay control system. Firstly, we will study the control problem. Then, we will deal with the topological structure of the solution set consisting of the compactness and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>R</mi><mi>σ</mi></msub></semantics></math></inline-formula> property. We will derive a mild solution to the above delay control problem by using the Laplace transform method.

E. I. Marukovich, V. Yu. Stetsenko, A. V. Stetsenko

The classical theory of crystallization of metal melts has been investigated. It is shown that it does not correspond to the second law of thermodynamics. Based on thermodynamic analysis, it was found that the classical theory of crystallization of metal melts is very problematic. To solve theoretical problems, it must be considered that the crystallization of metal melts is mainly an equilibrium process in which nanocrystals play a major role.

Rubin Battino, Trevor M. Letcher

Chemical thermodynamics is frequently thought of as being a hard subject and quite abstract. In fact, it is one of the most practical of subjects when you consider that the field of chemical engineering (responsible for endless useful applications) is effectively applied chemical thermodynamics. In this essay, examples of these applications are given, especially with respect to sustainability. The essay first considers the limits of thermodynamics and the constraints put on it in terms of the rigorous definitions of the principal function’s energy, entropy, and Gibbs energy.

Jurgen M. Honig

Frederick Richard Wayne McCourt

Salvatore Rionero

The onset of oscillatory bifurcations in a porous horizontal layer <i>L</i>, uniformly rotating about a vertical axis, with vertically stratified porosity, heated from below and salted from above and below, is investigated. Denoting by <inline-formula><math display="inline"><semantics><mrow><msub><mi>P</mi><mi>i</mi></msub><mo>,</mo><mspace width="0.166667em"></mspace><mrow><mo>(</mo><mi>i</mi><mo>=</mo><mn>1</mn><mo>,</mo><mn>2</mn><mo>)</mo></mrow></mrow></semantics></math></inline-formula>, the Prandtl numbers of the salt <inline-formula><math display="inline"><semantics><msub><mi>S</mi><mi>i</mi></msub></semantics></math></inline-formula> salting <i>L</i> from below <inline-formula><math display="inline"><semantics><mrow><mo>(</mo><mi>i</mi><mo>=</mo><mn>1</mn><mo>)</mo></mrow></semantics></math></inline-formula> and above <inline-formula><math display="inline"><semantics><mrow><mo>(</mo><mi>i</mi><mo>=</mo><mn>2</mn><mo>)</mo></mrow></semantics></math></inline-formula> respectively, it is shown that: (i) in <i>L</i> the oscillatory bifurcations can occur only if one of the structural conditions <inline-formula><math display="inline"><semantics><mrow><msub><mi>P</mi><mn>1</mn></msub><mo>></mo><mn>1</mn><mo>,</mo><mspace width="4pt"></mspace><msub><mi>P</mi><mn>2</mn></msub><mo><</mo><mn>1</mn></mrow></semantics></math></inline-formula> or <inline-formula><math display="inline"><semantics><mrow><msub><mi>P</mi><mn>1</mn></msub><mo>=</mo><mn>1</mn><mo>,</mo><mspace width="4pt"></mspace><msub><mi>P</mi><mn>2</mn></msub><mo><</mo><mn>1</mn></mrow></semantics></math></inline-formula> or <inline-formula><math display="inline"><semantics><mrow><msub><mi>P</mi><mn>1</mn></msub><mo>></mo><mn>1</mn><mo>,</mo><mspace width="4pt"></mspace><msub><mi>P</mi><mn>2</mn></msub><mo>=</mo><mn>1</mn></mrow></semantics></math></inline-formula> is verified; (ii) exists a bound <inline-formula><math display="inline"><semantics><msub><mover accent="true"><mi>R</mi><mo>¯</mo></mover><mn>2</mn></msub></semantics></math></inline-formula> for the Rayleigh number <inline-formula><math display="inline"><semantics><msub><mi>R</mi><mn>2</mn></msub></semantics></math></inline-formula> of <inline-formula><math display="inline"><semantics><msub><mi>S</mi><mn>2</mn></msub></semantics></math></inline-formula> such that <inline-formula><math display="inline"><semantics><mrow><msub><mi>R</mi><mn>2</mn></msub><mo><</mo><msub><mover accent="true"><mi>R</mi><mo>¯</mo></mover><mn>2</mn></msub></mrow></semantics></math></inline-formula> guarantees the absence of cold convection; (iii) via a new approach based on the instability power of each coefficient of the spectrum equation, criteria of existence, location and frequency of oscillatory (Hopf) bifurcations are furnished for any porosity stratification law. These criteria, as far as we know are, for the case at stake, the first criteria of Hopf bifurcations appearing in literature. We are confident that, via experimental results, will be validated.

Saima Rashid, Rehana Ashraf, Fatimah S. Bayones

This article investigates the semi-analytical method coupled with a new hybrid fuzzy integral transform and the Adomian decomposition method via the notion of fuzziness known as the Elzaki Adomian decomposition method (briefly, EADM). In addition, we apply this method to the time-fractional Swift–Hohenberg equation (SHe) with various initial conditions (IC) under gH-differentiability. Some aspects of the fuzzy Caputo fractional derivative (CFD) with the Elzaki transform are presented. Moreover, we established the general formulation and approximate findings by testing examples in series form of the models under investigation with success. With the aid of the projected method, we establish the approximate analytical results of SHe with graphical representations of initial value problems by inserting the uncertainty parameter <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0</mn><mo>≤</mo><mo>℘</mo><mo>≤</mo><mn>1</mn></mrow></semantics></math></inline-formula> with different fractional orders. It is expected that fuzzy EADM will be powerful and accurate in configuring numerical solutions to nonlinear fuzzy fractional partial differential equations arising in physical and complex structures.

Linzhu Wang, Zuobing Xi, Changrong Li

To investigate the modification of type B inclusions in high-carbon hard-wire steel with Ca treatment, Si-Ca alloy was added to high-carbon hard-steel, and the composition, morphology, size, quantity, and distribution of inclusions were observed. The samples were investigated by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The experimental thermal results showed that the modification effect of inclusion was better in high-carbon hard-wire steel with Al of 0.0053% and Ca of 0.0029% than that in steel with Al of 0.011% and Ca of 0.0052%, in which the inclusions were mainly spherical semi-liquid and liquid CA₂, CA, and C₁₂A₇. The inclusion size decreased from 3.2 μm to 2.1 μm. The degree of inclusions segregation was reduced in high-carbon hard-wire steels after calcium treatment. The results indicate that the modification of inclusions is conducive to obtaining dispersed inclusions with fine size. The ratio of length to width decreased and tended to be 1 with the increase in CaO content in the inclusion. When the content of CaO was higher than 30%, the aspect ratio was in the range of 1 to 1.2. The relationship between the activity of aluminum and calcium and the inclusions type at equilibrium in high-carbon hard-wire steel was estimated using classical thermodynamics. The calculated results were consistent with the experimental results. The thermodynamic software Factsage was used to analyze the effect of aluminum and calcium additions on the type and quality of inclusions in high-carbon hard-wire steels. The modification law and mechanism of type B inclusions in high-carbon hard-wire steels are discussed.

Paolo Abiuso, Harry J. D. Miller, Martí Perarnau-Llobet et al.

Differential geometry offers a powerful framework for optimising and characterising finite-time thermodynamic processes, both classical and quantum. Here, we start by a pedagogical introduction to the notion of thermodynamic length. We review and connect different frameworks where it emerges in the quantum regime: adiabatically driven closed systems, time-dependent Lindblad master equations, and discrete processes. A geometric lower bound on entropy production in finitetime is then presented, which represents a quantum generalisation of the original classical bound. Following this, we review and develop some general principles for the optimisation of thermodynamic processes in the linear-response regime. These include constant speed of control variation according to the thermodynamic metric, absence of quantum coherence, and optimality of small cycles around the point of maximal ratio between heat capacity and relaxation time for Carnot engines.

P. Ván

How can we derive the evolution equations of dissipative systems? What is the relation between the different approaches? How much do we understand the fundamental aspects of a second law based framework? Is there a hierarchy of dissipative and ideal theories at all? How far can we reach with the new methods of nonequilibrium thermodynamics?

Soundhararajan Gopi, Akashnathan Aranganathan, Athi N. Naganathan

Statistical mechanical models that afford an intermediate resolution between macroscopic chemical models and all-atom simulations have been successful in capturing folding behaviors of many small single-domain proteins. However, the applicability of one such successful approach, the Wako-Saitô-Muñoz-Eaton (WSME) model, is limited by the size of the protein as the number of conformations grows exponentially with protein length. In this work, we surmount this size limitation by introducing a novel approximation that treats stretches of 3 or 4 residues as blocks, thus reducing the phase space by nearly three orders of magnitude. The performance of the ‘bWSME’ model is validated by comparing the predictions for a globular enzyme (RNase H) and a repeat protein (IκBα), against experimental observables and the model without block approximation. Finally, as a proof of concept, we predict the free-energy surface of the 370-residue, multi-domain maltose binding protein and identify an intermediate in good agreement with single-molecule force-spectroscopy measurements. The bWSME model can thus be employed as a quantitative predictive tool to explore the conformational landscapes of large proteins, extract the structural features of putative intermediates, identify parallel folding paths, and thus aid in the interpretation of both ensemble and single-molecule experiments.

Ruth Gregory, Andrew Scoins

We introduce a new set of chemical variables for the accelerating black hole. We show how these expressions suggest that conical defects emerging from a black hole can be considered as true hair – a new charge that the black hole can carry – and discuss the impact of conical deficits on black hole thermodynamics from this ‘chemical’ perspective. We conclude by proving a new Reverse Isoperimetric Inequality for black holes with conical defects.