Thermodynamic System Research Articles

Entropy‐based method considering nonlinear hardening effect to predict the crack propagation life of superalloy GH4169 at elevated temperature

AbstractThis paper aims to determine the relationship between thermodynamic entropy generation and fatigue crack propagation life of superalloy GH4169 at 300–650°C. The entire specimen was considered as the thermodynamic system. The plastic energy dissipation in the crack tip was obtained by finite element simulation utilizing the Chaboche nonlinear hardening model. Then the cyclic entropy generation rate (CEGR) and the accumulated entropy generation are calculated by combining simulation and experimental methods. Results show that the CEGR is a power function of the stress intensity factor range, and it is almost a constant at fatigue failure. The fatigue fracture entropy (FFE) increases as fatigue cycles at failure increase at constant temperature, but it first decreases and then increases when temperature increases from 300 to 650°C. A fatigue life prediction model based on the thermodynamic damage parameter is established and verified by comparison with experimental results and available data in the literature.

Modified Gravity in the Presence of Matter Creation: Scenario for the Late Universe.

We consider a dynamic scenario for characterizing the late Universe evolution, aiming to mitigate the Hubble tension. Specifically, we consider a metric f(R) gravity in the Jordan frame which is implemented to the dynamics of a flat isotropic Universe. This cosmological model incorporates a matter creation process, due to the time variation of the cosmological gravitational field. We model particle creation by representing the isotropic Universe (specifically, a given fiducial volume) as an open thermodynamic system. The resulting dynamical model involves four unknowns: the Hubble parameter, the non-minimally coupled scalar field, its potential, and the energy density of the matter component. We impose suitable conditions to derive a closed system for these functions of the redshift. In this model, the vacuum energy density of the present Universe is determined by the scalar field potential, in line with the modified gravity scenario. Hence, we construct a viable model, determining the form of the f(R) theory a posteriori and appropriately constraining the phenomenological parameters of the matter creation process to eliminate tachyon modes. Finally, by analyzing the allowed parameter space, we demonstrate that the Planck evolution of the Hubble parameter can be reconciled with the late Universe dynamics, thus alleviating the Hubble tension.

Thermodynamic Topology of Topological Black Hole in F(R)-ModMax Gravity’s Rainbow

Abstract In order to include the effect of high energy and topological parameters on black holes in $\mathrm{ F}(R)$ gravity, we consider two corrections to this gravity: energy-dependent spacetime with different topological constants, and a nonlinear electrodynamics field. In other words, we combine $\mathrm{ F}(R)$ gravity’s rainbow with ModMax nonlinear electrodynamics theory to see the effects of high energy and topological parameters on the physics of black holes. For this purpose, we first extract topological black hole solutions in $\mathrm{ F}(R)$-ModMax gravity’s rainbow. Then, by considering black holes as thermodynamic systems, we obtain thermodynamic quantities and check the first law of thermodynamics. The effect of the topological parameter on the Hawking temperature and the total mass of black holes is obvious. We also discuss the thermodynamic topology of topological black holes in $\mathrm{ F}(R)$-ModMax gravity’s rainbow using the off-shell free energy method. In this formalism, black holes are assumed to be equivalent to defects in their thermodynamic spaces. For our analysis, we consider two different types of thermodynamic ensembles. These are: fixed q ensemble and fixed $\phi$ ensemble. We take into account all the different types of curvature hypersurfaces that can be constructed in these black holes. The local and global topology of these black holes are studied by computing the topological charges at the defects in their thermodynamic spaces. Finally, in accordance with their topological charges, we classify the black holes into three topological classes with total winding numbers corresponding to $-1, 0$, and 1. We observe that the topological classes of these black holes are dependent on the value of the rainbow function, the sign of the scalar curvature, and the choice of ensembles.

Enhancing thermodynamic performance with an advanced combined power and refrigeration cycle with dual LNG cold energy utilization

Utilizing waste heat to drive thermodynamic systems is imperative for improving energy efficiency, thereby improving sustainability. A combined cooling and power systems (CCP) utilizes heat from a temperature source to deliver both power and cooling. However, CCP systems utilizing LNG cold energy suffers from low second law efficiency due to significant temperature differences. To address this, an “Advanced Power and Cooling with LNG Utilization (ACPLU)” system is proposed, integrating a cascaded transcritical carbon dioxide (TCO2)-LNG cycle with an Organic Rankine cycle (ORC) for improved power generation and an absorption refrigeration system (ARS) for simultaneous cooling. This study evaluates the second law efficiency, net work output, and exergy destruction performance through a sensitivity analysis, optimizing variables such as heat source temperature, superheater temperature difference, ORC and CO2 turbine inlet and condenser pressures, evaporator temperature, and pinch point temperatures of heat exchangers and generator. Compared to previous studies on CCP systems, the ACPLU shows a superior performance, with a second law efficiency of 27.3 % and a net work output of 11.76 MW. Cyclopentane as an ORC working fluid resulted in the highest second law efficiency of 29.06 % and net work output of 12.27 MW. Parametric analysis suggested that heat source temperature significantly impacts net power output. The exergy analysis concluded that a high-pressure ratio and good thermal match between the heat exchangers enhance overall performance. Utilizing artificial neural network (ANN) to produce a multiple-input-multiple-output (MIMO) objective function and performing multi-objective optimization (MOO) using genetic algorithm (GA), an improved second law efficiency and net power output by 28.11 % and 14.16 MW respectively, with pentane as the working fluid, is demonstrated. An average cost rate of 9.121 $/GJ was observed through a thermo-economic analysis. The ACPLU system is promising for medium temperature waste heat recovery, such as, pharmaceutical manufacturing plants.

Topology and phase transition for EPYM AdS black hole in thermal potential

As we all know the local topological properties of thermodynamical systems can be expressed by the winding numbers as the defects. The topological number that is the sum of all winding numbers can be used to classify the global topological nature of thermodynamical systems. In this paper, we construct a kind of thermal potential and then put the Einstein-power-Yang-Mills AdS black hole in it. Through the analysis of the geometric characteristics of the thermal potential based on the complex analysis we find the topological number is an invariant that is same as shown in the way of the Duan's ϕ-mapping topological current [Sci. Sin. 9, 1072 (1979)]. Furthermore, we adopt the Kramer's escape rate method to investigate the intensity of the first-order phase transition.

Thermal analysis of the Rindler–Schwarzschild black hole via corrected entropy

In this study, we investigate the thermodynamic characteristics of the Rindler–Schwarzschild black hole solution. Our analysis encompasses the examination of energy emission, Gibbs free energy, and thermal fluctuations. We calculate various quantities such as the Hawking temperature, geometric mass, and heat capacity to assess the local and global thermodynamic stability. The temperature of the black hole is determined using the first law of thermodynamics, while the energy emission rate is evaluated as well. By computing the Gibbs free energy, we explore the phase transition behavior exhibited by Rindler–Schwarzschild black hole, specifically examining the swallowing tails. Moreover, we derive the corrected entropy to investigate the influence of thermal fluctuations on small and large black holes. Notably, we compare the impact of correction terms on the thermodynamic system by comparing the results obtained for large black holes and small black holes.

Thermodynamic Simulation Model of Copper Side-Blown Smelting Process

In this study, the thermodynamic simulation model and system of the copper side-blown smelting process were established using the chemical equilibrium constant method, based on the process reaction mechanism, multiphase equilibrium principle, and MetCal software platform (MetCal v7.81). Under typical production conditions, the composition of the product and the distribution behavior of impurity elements were simulated. The results indicate that the average relative error between the calculated mass fractions of major elements such as Cu, S, Fe, SiO2, CaO, MgO, and Al2O3 in copper matte and smelting slag, and the actual production values, is 4.25%. Additionally, the average relative error between the calculated distribution ratios of impurity elements such as Pb, Zn, As, Bi, Mo, Au, and Ag in copper matte and smelting slag, and the actual production data, is 6.74%. Therefore, this model and calculation system accurately reflects the actual production situation of the copper side-blown smelting process well and has potential to predict process output accurately while optimizing process parameters, effectively guiding production practice.

The Bellman equation and optimal local flipping strategies for kinetic Ising models

There is a deep connection between thermodynamics, information and work extraction. Ever since the birth of thermodynamics, various types of Maxwell demons have been introduced in order to deepen our understanding of the second law. Thanks to them, it has been shown that there is a deep connection between thermodynamics and information, and between information and work in a thermal system. In this paper we study the problem of energy extraction from a thermodynamic system satisfying detailed balance by an agent with perfect information, e.g. one that has an optimal strategy, given by the solution of the Bellman equation, in the context of Ising models. We call these agents kobolds, in contrast to Maxwell’s demons which do not necessarily need to satisfy detailed balance. This is in stark contrast with typical Monte Carlo algorithms, which choose an action at random at each time step. It is thus natural to compare the behavior of these kobolds to a Metropolis algorithm. For various Ising models, we study numerically and analytically the properties of the optimal strategies, showing that there is a transition in the behavior of the kobold as a function of the parameter characterizing its strategy.

Uncertainty relations in thermodynamics of irreversible processes on a mesoscopic scale

Studies of mesoscopic structures have become a leading and rapidly evolving research field ranging from physics, chemistry, and mineralogy to life sciences. The increasing miniaturization of devices with length scales of a few nanometers is leading to radical changes in the realization of new materials and in shedding light on our understanding of the fundamental laws of nature that govern the dynamics of systems at the mesoscopic scale. We investigate thermodynamic processes in small systems in Onsager’s region based on recent experimental results and previous theoretical research. We show that fundamental quantities such as the total entropy production, the thermodynamic variables conjugate to the thermodynamic forces, and the Glansdorff–Prigogine’s dissipative variable may be discretized at the mesoscopic scale. We establish the canonical com- mutation rules (CCRs) valid at the mesoscopic scale. The numerical value of the discretization constant is estimated experimentally. The ultraviolet divergence problem is solved by applying the correspondence principle with Einstein–Prigogine’s fluctuations theory in the limit of macroscopic systems. Examples of quantization of thermodynamic systems out of the Onsager region are currently being finalized.

Theoretical and observational implications of Planck’s constant as a running fine structure constant

This paper explores how a reinterpretation of the generalized uncertainty principle as an effective variation of Planck’s constant provides a physical explanation for a number of fundamental quantities and couplings. In this context, a running fine structure constant is naturally emergent and the cosmological constant problem is solved, yielding a novel connection between gravitation and quantum field theories. The model could potentially clarify the recent experimental observations by the DESI Collaboration that could imply a fading of dark energy over time. When applied to quantum systems and their characteristic length scales, a simple geometric relationship between energy and entropy is disclosed. Lastly, a mass–radius relation for both quantum and classical systems reveals a phase transition-like behavior similar to thermodynamical systems, which we speculate to be a consequence of topological defects in the universe.

Intrinsic kinetics of steam methane reforming over a monolithic nickel catalyst in a fixed bed reactor system

The intrinsic kinetics of steam methane reforming were experimentally investigated using a monolithic nickel-based catalyst in a specially designed fixed bed system. All kinetic tests were performed under various operating conditions: steam to carbon ratio of 2 to 5, methane volumetric concentration in feed gas of 3 % to 9 %, temperature of 500 to 650 °C, and typical biogas compositions with N2 dilution (carbon dioxide 35.7–55.6 %, methane 44.4–64.3 %, with 86–91 % nitrogen dilution). A deconvolution process was applied during the rate calculation and the reaction orders with respect to different gases were determined, coupled with thermodynamic system analysis. The reaction mechanism was then proposed and a Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic model was established, followed by kinetic parameter estimations for the model and a further model validation with experimental data. Based on the model, the intrinsic kinetic of SMR reaction using monolithic catalysts was described. The validity and feasibility of applying the faster approach for kinetic parameter estimation were demonstrated, and this work is the first demonstration of a complex reaction system. Also, the reaction mechanism appeared to show a suitably high correlation with alternative and more sustainable methane sources (i.e. biogas).

Sea ice melt pond bathymetry reconstructed from aerial photographs using photogrammetry: a new method applied to MOSAiC data

Abstract. Melt ponds are a core component of the summer sea ice system in the Arctic, increasing the uptake of solar energy and impacting the ice-associated ecosystem. They were thus one of the key topics during the 1-year drift campaign Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) in the Transpolar Drift 2019/2020. Pond depth is a dominating factor in describing the surface meltwater volume; it is necessary to estimate budgets and used in model parameterization to simulate pond coverage evolution. However, observational data on pond depth are spatially and temporally strongly limited to a few in situ measurements. Pond bathymetry, which is pond depth spatially fully resolved, remains unexplored. Here, we present a newly developed method to derive pond bathymetry from aerial images. We determine it from a photogrammetric multi-view reconstruction of the summer ice surface topography. Based on images recorded on dedicated grid flights and facilitated assumptions, we were able to obtain pond depth with a mean deviation of 3.5 cm compared to manual in situ observations. The method is independent of pond color and sky conditions, which is an advantage over recently developed radiometric airborne retrieval methods. It can furthermore be implemented in any typical photogrammetry workflow. We present the retrieval algorithm, including requirements for the data recording and survey planning, and a correction method for refraction at the air–pond interface. In addition, we show how the retrieved surface topography model synergizes with the initial image data to retrieve the water level of individual ponds from the visually determined pond margins. We use the method to give a profound overview of the pond coverage on the MOSAiC floe, on which we found unexpected steady pond coverage and volume. We were able to derive individual pond properties of more than 1600 ponds on the floe, including their size, bathymetry, volume, surface elevation above sea level, and temporal evolution. We present a scaling factor for single in situ depth measurements, discuss the representativeness of in situ pond measurements and the importance of such high-resolution data for new satellite retrievals, and show indications for non-rigid pond bottoms. The study points out the great potential to derive geometric properties of the summer sea ice surface emerging from the increasingly available visual image data recorded from uncrewed aerial vehicles (UAVs) or aircraft, allowing for an integrated understanding and improved formulation of the thermodynamic and hydrological pond system in models.

Diffusion kinetics in a multicomponent thermodynamic system at small deviations from the equilibrium state

The theory of diffusion processes in solids has achieved significant results in recent decades, but the development of methods for calculating diffusion in a multicomponent thermodynamic system is still an urgent task. Problems of diffusion in solid and liquid solutions with small deviations from the equilibrium state, or fluctuations, are of significant interest. The work develops a general methodology for calculating diffusion flows in a multicomponent thermodynamic system for small deviations from the equilibrium state. A connection has been established between the mechanical approach to the analysis of generalized systems and the phenomenological equations of nonequilibrium thermodynamics. Examples are given of the use of the developed methodology for the analysis of carbide transformations in chromium steel.

A generalized presentation of multi-caloric effects based on exterior derivative theory and its applications * *Supported by National Science Foundations of China No. 12004195.

The emerging concept of multi-caloric effects, introduced in 2010, entails the application of multiple interplay fields to a thermodynamic system. While multi-caloric effects are the main focus of experimental endeavors, theoretical considerations fall short of providing a thorough understanding. This paper introduces a comprehensive presentation on multi-caloric effects, employing the method and theory of exterior derivative formations. It addresses every aspect of thermodynamic systems, showcasing its applicability to multi-caloric materials (both single-phase and multi-phase materials), and its adaptability to different scenarios (either in single or multiple force fields). The formulation of Maxwell relationships, characterized by their generality and universality, enables a clear prediction in entropy and temperature, facilitating a distinct identification between independent and interdependent contributions from multi-caloric effects. These insights hold significant importance in designing and developing specialized thermodynamic materials, optimizing functional performances and exploring innovative mechanisms.

Innovative Ex-Situ catalyst bed integration for LDPE plastic Pyrolysis: A thermodynamically closed system approach

The recycling of Low-Density Polyethylene (LDPE) poses a significant challenge due to its resistance to degradation and presence of impurities among the waste LDPE. This study introduces an innovative method for LDPE pyrolysis, aiming to enhance the efficiency of LDPE recycling and contribute to the circular economy of plastics. We utilized an HZSM-5 catalyst within a unique setup that incorporates a catalyst bed constructed from a quartz fibre membrane filter. This innovative hybrid method, a combination of in-situ and ex-situ modes, was designed to shield the catalyst from direct contact with undesired materials, thereby facilitating easy catalyst separation at the end of the process. Experiments were conducted in a high-pressure batch reactor, heated to 400 °C within a closed thermodynamic system. Parallel runs were performed for both pure and waste LDPE, with and without the catalyst. The catalytic pyrolysis resulted in an oil output of 40.3 % for waste LDPE and 43.5 % for pure LDPE, with a significant increase in aromatics when comparing thermal to catalytic pyrolysis. The calorific values of the pyrolysis liquids were found to be 46.2 for pure LDPE and 46.1 for waste LDPE, indicating their potential for sustainable hydrocarbon fuel synthesis. Following the catalytic pyrolysis, the spent catalyst underwent stepwise oxidation as a regeneration method, indicating a partial loss of activity but a similar influence on the degradation temperature as the fresh catalyst. This study not only presents a promising approach to LDPE recycling but also offers a comprehensive analysis of both the pyrolysis outputs and the spent catalyst. Such detailed analysis is crucial for refining the LDPE pyrolysis process and facilitating its scale-up for industrial applications.

Thermodynamic analysis of a hybrid ammonia-water refrigeration cycle with low-temperature solar heat

The performance of a solar-driven single-effect ammonia absorption refrigeration unit was studied numerically and experimentally. The thermal performance and unit operation status of small refrigerators were studied under various designing and operating conditions. A thermodynamic cycle scheme of hybrid ammonia-water refrigeration (HAWR) is proposed to operate in parallel with the compressor and ammonia absorption refrigeration, and the performance of the thermodynamic circulation system is evaluated by considering the thermodynamic coefficient and thermodynamic refrigeration ratio as evaluation indexes. Aspen Plus simulation software was introduced to simulate the HAWR and optimise the operation strategy. The results indicate that adjusting the compressor outlet pressure can stabilise the refrigeration capacity of the ammonia refrigeration system. The optimised working point pressure is 600 kPa, while the corresponding evaporation, condensation, absorption, and generation temperatures are 15 °C, 40 °C, 42 °C, and 85 °C respectively, the thermodynamic coefficient is 0.307, and the thermodynamic refrigeration ratio is 0.443. Under the rated cooling conditions, 44.3 % of the cooling capacity is driven by solar energy, and 55.7 % is driven by electric energy in the optimal working state. Under non-optimal working conditions, the proportion of the cooling capacity driven by electric energy is as high as 79.5 %. Under the conditions of sunny weather and with the absence of the compressor, the cooling capacity increases from 2.5 to 7.5 kW as the radiation intensity increases from 600 to 950 W/m2, while the system performance tends to be stable and the coefficient of performance maintains around 0.738 as the irradiation intensity exceeds 800 W/m2.

Thermodynamic analysis of Magnetically charged Euler–Heisenberg black holes with scalar hair via Renyi-entropy using logarithmic correction

In this article, we investigate the thermodynamic properties of the Euler–Heisenberg black hole solution with magnetic charge and scalar hair. We also examine the evaluation of thermal fluctuations, Gibbs free energy, and energy emission. The Hawking temperature, geometric mass, and heat capacity are among the numerous factors that are computed to evaluate local and global thermodynamic stability. The first law of thermodynamics is applied to determine the temperature of the black hole, and the energy emission rate is also calculated. We investigate the phase transition behavior of the Euler–Heisenberg black hole with scalar hair by computing the Gibbs free energy, with particular attention to characteristics like eating tails. We also obtain the corrected entropy to investigate the impact of thermal fluctuations on massive and small black holes. Notably, we contrast the outcomes for large and small black holes in order to examine the effects of correction terms on the thermodynamic system.

Thermodynamic model for memory

A thermodynamic model for memory formation is proposed. Key points include: 1) Any thought or consciousness corresponds to a thermodynamic system of nerve cells. 2) The system concept of nerve cells can only be described by thermodynamics of condensed matter. 3) The memory structure is logically associated with the system structure or the normal structure of biology. 4) The development of our thoughts is processed irreversibly, and numerous states or thoughts can be generated. 5) Memory formation results from the reorganization and change of cellular structures (or memory structures), which are related to nerve cell skeleton and membrane. Their alteration can change the excitability of nerve cells and the pathway of neural impulse conduction. 6) Amnesia results from the loss of thermodynamic stability of the memory structure, which can be achieved by different ways. Some related phenomena and facts are discussed. The analysis shows that thermodynamics can account for the basic properties of memory.

Optimal schedules for annealing algorithms.

Annealing algorithms such as simulated annealing and population annealing are widely used both for sampling the Gibbs distribution and solving optimization problems (i.e., finding ground states). For both statistical mechanics and optimization, additional parameters beyond temperature are often needed such as chemical potentials, external fields, or Lagrange multipliers enforcing constraints. In this paper we derive a formalism for optimal annealing schedules in multidimensional parameter spaces using methods from nonequilibrium statistical mechanics. The results are closely related to work on optimal control of thermodynamic systems [Sivak and Crooks, Phys. Rev. Lett. 108, 190602 (2012)0031-900710.1103/PhysRevLett.108.190602]. Within the formalism, we compare the efficiency of population annealing and multiple weighted runs of simulated annealing ("annealed importance sampling") and discuss the effects of nonergodicity on both algorithms. Theoretical results are supported by numerical simulations of spin glasses.

Thermodynamic phase transition and winding number for the third-order Lovelock black hole* *Supported by the National Natural Science Foundation of China (12105222, 12275216, 12247103)

Phase transition is important for understanding the nature and evolution of the black hole thermodynamic system. In this study, we predicted the phase transition of the third-order Lovelock black hole using the winding numbers in complex analysis, and qualitatively validated this prediction by the generalized free energy. For the 7<d<12-dimensional black holes in hyperbolic topology and the 7-dimensional black hole in spherical topology, the winding number obtained is three, which indicates that the system undergoes first-order and second-order phase transitions. For the 7<d<12-dimensional black holes in spherical topology, the winding number is four, and two scenarios of phase transitions exist, one involving a purely second-order phase transition and the other involving simultaneous first-order and second-order phase transitions. This result further deepens the research on black hole phase transitions using the complex analysis.