Entropy: Thermodynamics – Energy – Environment – Economy

Entropie - ISSN 2634-1476 - © ISTE Ltd

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Since 1857, the second law of thermodynamics has faced the challenge of Maxwell’s imagined demon. The widely accepted response to this challenge suggests that the demon requires a bit of information to work, and according to Landauer’s principle, the erasure of this bit must offset the entropy reduction achieved by the demon. Recent experiments involving two-state physical systems subject to thermal fluctuations at the nanoscale have aimed to either prove Landauer’s principle or to demonstrate Szilard engines or Maxwell’s demons in practice. We wrote the equations and developed a numerical model to simulate the evolution of these systems. The results highlight the distinction between thermodynamic entropy and information entropy. They demonstrate that Landauer’s principle has a limited range of applicability and that, using a two-state memory, it is possible to eliminate a small amount of entropy without expending energy—challenging the second law of thermodynamics at the nanoscale.

La Société Française de Thermique a pour objectif le développement et le rayonnement des sciences thermiques et énergétiques et de leurs applications. Cette année 2025, le 33e Congrès Français de Thermique s’est déroulé du 3 au 6 juin 2025 à Chambéry sur le thème Thermique, Energies renouvelables et Territoires.

We describe a new nodal simulation approach, and a corresponding theoretical model, to quantify thermal conduction through the solid phase in three-dimensional fibrous networks, with the impact of fiber-to-fiber thermal contact resistances. We demonstrate that the solid thermal conductivity can be calculated by a master curve, based solely on geometric parameters of the medium, particularly in the case of low-connectivity. This provides a powerful predictive tool to be applied to the study of real insulation materials, to develop in particular optimization strategies based on structural parameters.

Measuring temperature fields in semi-transparent media requires the knowledge of optothermal properties. While current techniques are well established for isothermal thin films, they remain unexplored for thick films with temperature gradients. This study proposes to generalize current methods to thick media by combining transmittance measurement based on transmission heterodyne photothermal imaging (TPHI) and optothermal modeling. In this work, we demonstrate the validity of our model, followed by the measurements of thermotransmittance and thermoreflectance coefficients for 3 different materials.

Local Climate Zones (LCZs) classify urban areas based on their morphology and thermal properties. Using the WUDAPT Level 0 methodology, this study develops an LCZs map for Lyon by leveraging satellite imagery and open-source tools. The process involves collecting training data, performing classification, and validating results. The LCZs map reveals Lyon’s diverse urban structures, offering valuable insights for climate studies and sustainable urban planning. This study highlights the utility of LCZs datasets in addressing challenges posed by urbanization and climate change.

The behavior of pool fires and the ignition risk of unburnt gases are analyzed in a reduced-scale model of a ventilated historic chamber. Experiments were carried out with various pool diameters and air exchange rates to examine fire behavior in a confined environment. The results show that fire behavior varies depending on the combustion regime. The risk assessment, based on a global approach, indicates that the largest pool fire presents a high ignition risk, while the smallest remains below the ignition threshold. This study provides perspectives for fire safety in historic buildings.