Thermodynamic Geometry Research Articles

Thermodynamic geometry of STU black holes

This work investigates the phase structure of STU black holes with uniform charges by utilizing the New Thermodynamic Geometry (NTG) approach. The study explores the intriguing relationship between heat capacity phase transitions and curvature singularities, employing the NTG formalism. The analysis encompasses an examination of phase transitions along the T − S and Q − Φ planes, a study of critical exponents, and an assessment of black hole stability. The NTG geometry is applied in both the normal and extended phase spaces, revealing valuable insights into the thermodynamic behavior and stability of STU black holes. Meanwhile, a closer examination of NTG geometry shows a positive correlation in the sign between the extrinsic curvature and the heat capacity, which is incompatible with the curvature singularity. Overall, this study contributes to our understanding of the phase transitions and thermodynamic properties of STU black holes, shedding light on the intricate interplay between curvature singularities and the stability of black holes in diverse thermodynamic scenarios.

Thermal stability of black hole in bumblebee gravity with cosmological constant

This paper delves into the intriguing topic of the thermal stability of black holes (BHs) in the unique framework of bumblebee gravity. Our analysis primarily focuses on thermodynamic stability by examining the event horizon, black hole mass, thermal temperature and heat capacity. Additionally, we explore the intricacies of thermodynamic geometries such as Ruppeiner and Weinhold formulations and calculate their respective scalar curvatures in the context of bumblebee gravity. In our investigation, we also delve into the concept of phase transition through Gibbs free energy and the fascinating phenomenon of BH evaporation by energy emission. This research provides valuable insights into the complex thermodynamic properties of BHs and enhances our understanding of bumblebee gravity. We study the bosonic tunneling with spin-1 tunneling radiation in BHs. Initially, the generalized uncertainty principle (GUP) was used to correct the field equation (FE) for vector particles with spin-1 and demonstrate that the Hawking temperature rises with an improvement in the GUP and the radial component of the vector field but is unaffected by the radial components.

Thermodynamics and microstructures of Euler–Heisenberg black hole in a cavity

Euler–Heisenberg black holes with quantum electrodynamics (QED) correction are embraced by a cavity in this paper, which serves as a boundary of the black hole spacetime and contributes to the equilibrium of the system. We explore the thermodynamic properties of the black hole, including the phase transitions and phase structures. The small/large black hole phase transition occurs for a negative QED parameter, while the reentrant phase transition can be observed for a small positive QED parameter. Then the thermodynamic geometry is investigated to diagnose microscopic interactions of black hole thermodynamic systems. For the reentrant phase transition, the small black holes are dominated by repulsion for the first-order coexistence curve, while the interaction between the small black hole molecules could be attractive or repulsive for the small/large black hole phase transition.

Impact of barrow entropy on geometrothermodynamics of specific black holes

In this paper, we study the effect of Barrow entropy on the thermodynamic properties and geometry of specific black holes along with the nonlinear source. We investigate the mass, temperature, thermodynamic variable, and electric potential of the black hole as well. Furthermore, we examine the behavior of heat capacity to check the stability of a black hole. Geometrothermodynamics allows us to describe interactions between thermodynamics, critical points, and phase transitions by considering the geometric characteristics of the thermodynamic equilibrium space. Our analysis demonstrates that these findings are consistent with the results derived from the classical thermodynamics of black holes.

Geometric Thermoelectric Pump: Energy Harvesting beyond Seebeck and Pyroelectric Effects

Thermal-electric conversion is crucial for smart energy control and harvesting, such as thermal sensing and waste heat recovering. So far, researchers are aware of two main ways of direct thermal-electric conversion, Seebeck and pyroelectric effects, each with different working mechanisms, conditions and limitations. Here, we report the concept of Geometric Thermoelectric Pump (GTEP), as the third way of thermal-electric conversion beyond Seebeck and pyroelectric effects. In contrast to Seebeck effect that requires spatial temperature difference, GTEP converts the time-dependent ambient temperature fluctuation into electricity. Moreover, GTEP does not require polar materials but applies to general conducting systems, and thus is also distinct from pyroelectric effect. We demonstrate that GTEP results from the temperature-fluctuation-induced charge redistribution, which has a deep connection to the topological geometric phase in non-Hermitian dynamics, as a consequence of the fundamental nonequilibrium thermodynamic geometry. The findings advance our understanding of geometric phase induced multiple-physics-coupled pump effect and provide new means of thermal-electric energy harvesting.

Development of an ejector for passive hydrogen recirculation in PEM fuel cell systems by applying 2D CFD simulation

The anode subsystem is a major energy consumer of polymer-electrolyte-membrane (PEM) fuel cell systems. A passive hydrogen recirculation system, like an ejector, is an excellent solution to maximize hydrogen utilization while maintaining low parasitic losses. However, high development efforts are necessary to maximize the performance of the ejector for the entire operating range. This research paper provides part of a toolchain for ejector development, consisting in particular of a multi-parameter simulation based on rotational symmetric 2D CFD. The 2D CFD greatly helps optimize the design of the ejector, reducing development effort, and increasing accuracy. In addition, the main correlations between thermodynamic states and geometry on the entrainment ratio are evaluated. Subsequently, an ejector is designed for a PEM fuel cell application using 2D CFD and the results show in which operating range a single ejector can be applied. This toolchain enables rapid design and optimization of ejector geometry, saving development time and cost while increasing accuracy and extending the operating range.

Conformal Fisher information metric with torsion

We consider torsion in parameter manifolds that arises via conformal transformations of the Fisher information metric, and define it for information geometry of a wide class of physical systems. The torsion can be used to differentiate between probability distribution functions that otherwise have the same scalar curvature and hence define similar geometries. In the context of thermodynamic geometry, our construction gives rise to a new scalar—the torsion scalar defined on the manifold, while retaining known physical features related to other scalar quantities. We analyse this in the context of the Van der Waals and the Curie–Weiss models. In both cases, the torsion scalar has non trivial behaviour on the spinodal curve. We also briefly comment on the one dimensional classical Ising model and show that the torsion scalar diverges exponentially near criticality.

Design optimization of compact gas turbine and steam combined cycles for combined heat and power production in a FPSO system–A case study

This case study aims to cover a wide range of relevant aspects related to combined cycle design, mechanical integrity and operational reliability for cogeneration of heat and power in FPSO systems. The methods consist of combined optimization of combined cycle thermodynamic design and geometry of steam generator; vibration analysis for flow induced vibrations; and thermal stress estimation of casings during cold start-stop scenarios. Challenges and opportunities for reliable water treatment systems are explored. The results show that small tubes, a compact tube bundle and a low condensation temperature reduces the once-trough steam generator (OTSG) weight. The vibrations numerical simulations in this work support the standard recommendations of using 35 times tube OD as upper limit for the unsupported tube length, which could be used as a reasonable design criterion. Thermal stresses analysis indicates that the design of beam arrangement, location, and stiffness of beams has a major impact on thermal stresses, and can be optimized to different plate thicknesses in order to avoid fatigue damage. Focus should be on reducing leaks of deaerator, steam turbine and condenser. It is recommended to add Na sensors after condenser and investigating the use of Electrodeionization (EDI) technology for make-up water production from seawater.

Non-perturbative correction to thermodynamics of conformally dressed [formula omitted] black hole

We extend the study of corrected thermodynamics for the 3D black holes conformally coupled to scalar field up to non-perturbative level. We calculate the exponential correction to entropy arises due to the microstate counting for quantum states on the boundary. This exponential correction in entropy attributes to the other thermodynamical quantities also. We study the stability and phase transition for this system of black hole under the influence of non-perturbative correction. We also discuss the quantum work associated with exponential corrected entropy. Finally, we justify the results from the view point of thermodynamic geometry.

Geometrical aspects of the multicritical phase diagrams for the Blume–Emery–Griffiths model

As a continuation of our preceding work [R. Erdem and N. Alata, Eur. Phys. J. Plus 135, 911 (2020), https://doi.org/10.1140/epjp/s13360-020-00934-3], we used the thermodynamic geometry in the Ruppeiner formalism to study the geometrical aspects of the multicritical phase diagrams for the spin-1 Blume-Emery- Griffiths model in the presence of crystal field. We derived an expression for the thermodynamic curvature or Ricci scalar (R) and analyzed its temperature and crystal field behaviours near interesting critical and multicritical points. Our findings are presented as geometrical phase diagrams including critical and multicritical topology. From these diagrams, new vanishing curvature lines (R = 0) extending into the ferromagnetic or paramagnetic phases beyond the critical points and zero point temperature are observed.

Thermal geometries and the Joule–Thomson expansion of modified charged and slowly rotating black holes

Thermodynamics of charged and slowly rotating black holes in 4D Gauss–Bonnet gravity has attracted a great deal of attention due to its intrinsic complications and rich phase structures. In this paper, we revisit the thermodynamics of charged and slowly rotating black holes and provide the correct thermodynamic volume and entropy. Thermodynamic geometries are a powerful tool to study the microstructure of black holes. Based on the Hessian matrix of the black hole mass, we introduce thermodynamic geometric methods and give its scalar curvature (Ruppeiner and Weinhold). Furthermore, we investigate the Joule–Thomson expansion of slowly rotating black hole in 4D Gauss–Bonnet gravity in this research study. Interestingly, we explicitly state that the expression of the Joule–Thomson coefficient is obtained from the basic formulas of enthalpy and temperature. Then, we obtain the isenthalpic curve in the T − P graph and demonstrate the cooling–heating region by the inversion curve. The inversion temperature and inversion curves are obtained, and we investigate the similarities and differences between van der Waals fluids and charged fluids.

Thermodynamic geometry and universal properties of charged anti-de Sitter black hole immersed in perfect fluid dark matter

Thermodynamic geometry and universal properties of charged anti-de Sitter black hole immersed in perfect fluid dark matter

An epitrochoidal rotary reactor for solar-driven hydrogen production based on the redox cycling of ceria: Thermodynamic analysis and geometry optimization

An epitrochoidal rotary reactor for solar-driven hydrogen production based on the redox cycling of ceria: Thermodynamic analysis and geometry optimization

Conjugate heat transfer and flow around tandem tubes: Effect of thermophysical parameters and tube arrangement

Thermodynamic calculation and geometry parameters are key issues in thermo-equipment design. The flow and conjugate heat transfer around the tandem tubes are numerically investigated, in which the examined parameters include thermal conductivity ratio (kr), volumetric heat capacity ratio (φr), and Biot number (Bi) which are varied from 200 to 800, 1000 to 3000, and 0.1 to 1.0, respectively. Further, the effect of the space ratio (L/D = 1.0–10.0) between the tandem tubes on the flow pattern and heat transfer is also studied to obtain a proper tube arrangement. In particular, a difference method for lattice Boltzmann algorithm is validated and then adopted on the curve fluid-solid interface to calculate the conjugate heat transfer. Results demonstrate that the thermal conductivity ratio significantly affects the heat transfer performance of the tube while the volumetric heat capacity ratio only affects the rate of heating process. The growth in thermal conductivity ratio leads to a more uniform temperature distribution and higher thermal performance, and this effect becomes weaker as the kr grows. Meanwhile, the increase of Bi strengthens the convective heat transfer inside the tube, further changing the dominant way of heat transfer. Finally, the flow varies considerably with the space ratio, classifying into four typical regimes. It is found that the Nu is sensitive to the flow regime and the case with L/D = 4.0 provides the best thermal performance of tandem tubes. These results can provide more realistic predictions and indications in thermo-equipment design.

Finite-time bounds on the probabilistic violation of the second law of thermodynamics

Jarzynski’s equality sets a strong bound on the probability of violating the second law of thermodynamics by extracting work beyond the free energy difference. We derive finite-time refinements to this bound for driven systems in contact with a thermal Markovian environment, which can be expressed in terms of the geometric notion of thermodynamic length. We show that finite-time protocols converge to Jarzynski’s bound at a rate slower than 1/\sqrt{\tau}1/τ, where \tauτ is the total time of the work-extraction protocol. Our result highlights a new application of minimal dissipation processes and demonstrates a connection between thermodynamic geometry and the higher order statistical properties of work.

Thermodynamic geometry of ideal quantum gases: a general framework and a geometric picture of BEC-enhanced heat engines

Thermodynamic geometry provides a physically transparent framework to describe thermodynamic processes in meso- and micro-scale systems that are driven by slow variations of external control parameters. Focusing on periodic driving for thermal machines, we extend this framework to ideal quantum gases. To this end, we show that the standard approach of equilibrium physics, where a grand-canonical ensemble is used to model a canonical one by fixing the mean particle number through the chemical potential, can be extended to the slow driving regime in a thermodynamically consistent way. As a key application of our theory, we use a Lindblad-type quantum master equation to work out a dynamical model of a quantum many-body engine using a harmonically trapped Bose-gas. Our results provide a geometric picture of the Bose–Einstein condensate-induced power enhancement that was previously predicted for this type of engine on the basis of an endoreversible model (Myers et al 2022 New J. Phys. 24 025001). Using an earlier derived universal trade-off relation between power and efficiency as a benchmark, we further show that the Bose-gas engine can deliver significantly more power at given efficiency than an equally large collection of single-body engines. Our work paves the way for a more general thermodynamic framework that makes it possible to systematically assess the impact of quantum many-body effects on the performance of thermal machines.

Phase transitions and thermodynamic geometry of a Kerr–Newman black hole in a cavity

Phase transitions and thermodynamic geometry of a Kerr–Newman black hole in a cavity

Unified, Geometric Framework for Nonequilibrium Protocol Optimization.

Controlling thermodynamic cycles to minimize the dissipated heat is a long-standing goal in thermodynamics, and more recently, a central challenge in stochastic thermodynamics for nanoscale systems. Here, we introduce a theoretical and computational framework for optimizing nonequilibrium control protocols that can transform a system between two distributions in a minimally dissipative fashion. These protocols optimally transport a system along paths through the space of probability distributions that minimize the dissipative cost of a transformation. Furthermore, we show that the thermodynamic metric-determined via a linear response approach-can be directly derived from the same objective function that is optimized in the optimal transport problem, thus providing a unified perspective on thermodynamic geometries. We investigate this unified geometric framework in two model systems and observe that our procedure for optimizing control protocols is robust beyond linear response.

Impact of exponential entropy on the thermodynamics of 4D charged Einstein-Guass-Bonnet-AdS black hole

In the presence of exponential corrected entropy, we investigate the thermal stability and phase transitions of a charged 4D Einstein-Gauss-Bonnet-AdS black hole by using the formalism known as the deflection angle formalism. Specifically, with the help of the elliptic function analysis, we investigate the phase structure of the black hole by focusing on the optical aspects. This has come to our attention that the thermal variation of the deflection angle can be used to generate both stable and unstable phases. The Hawking-Page phase transition, which is derived from the Gibbs free energy optical dependence, is another issue that we investigate with the help of exponentially corrected entropy. In addition, there are particular points along the deflection angle that produce a transition between large and small black holes. Our Gibbs free energy versus deflection angle behavior showed that the deflection angle can be utilized as a relevant quantity to determine the critical behavior of AdS black holes. In the presence of exponential corrected entropy, the thermodynamic geometry of a charged 4D Einstein-Guass-Bonnet-AdS black hole is also discussed.

Contact and metric structures in black hole chemistry

We review recent studies of contact and thermodynamic geometry for black holes in AdS spacetimes in the extended thermodynamics framework. The cosmological constant gives rise to the notion of pressure P = −Λ/8π and, subsequently a conjugate volume V, thereby leading to a close analogy with hydrostatic thermodynamic systems. To begin with, we review the contact geometry approach to thermodynamics in general and then consider thermodynamic metrics constructed as the Hessians of various thermodynamic potentials. We then study their correspondence to statistical ensembles for systems with two-dimensional spaces of equilibrium states. From the zeroes and divergences of the curvature scalar obtained from the metric, we carefully analyze the issue of ensemble non-equivalence and show certain complimentary behaviors in the description of a thermodynamic system. Following a thorough analysis of the familiar van der Waals system, we turn our attention to black holes in extended phase space. Considering the example of charged AdS black holes, we discuss the generic features of their thermodynamic geometry in detail. The relationship of the thermodynamic curvature(s) with critical points as well as microscopic interactions in black holes is also briefly explored. We finally set up the thermodynamic geometry for finite temperature gauge theories dual to black holes in AdS via holographic correspondence and comment on recent progress.