Henri Poincaré: The Status of Mechanical Explanations and the Foundations of Statistical Mechanics

The first goal of this paper is to show the evolution of Poincaré’s opinion on the mechanistic reduction of the principles of thermodynamics, placing it in the context of the science of his time. The second is to present some of his work in 1890 on the foundations of statistical mechanics. He became interested first in thermodynamics and its relation with mechanics, drawing on the work of Helm-holtz on monocyclic systems. After a period of skepticism concerning the kinetic theory, he read some of Maxwell’s memories and contributed to the foundations of statistical mechanics. I also show that Poincaré's contributions to the founda-tions of statistical mechanics are closely linked to his work in celestial mechanics and its interest in probability theory and its role in physics

An innovative PCM Storage System to enhance Building Energy Autonomy: experimental and numerical characterization

Abstract Even if the use of renewable energy sources towards autonomous buildings is promising, it is facing a fundamental issue: the shift between energy production and heating energy demand. We propose in this paper a thermally controlled storage solution using phase change materials integrated in the building walls. Its main advantage lies in the ability to activate on-demand the thermal discharge by ventilating the phase change materials. A test bench has been manufactured. Tests were performed which proved the feasibility of overnight storage with morning discharge allowing an internal air temperature increase of 5°C. Simulations based on experimental results showed that an integration in real buildings with photovoltaic energy production allows to significantly increase the building energy autonomy. If the improvement is important for all types of buildings, it showed larger absolute improvements for weakly insulated buildings than for buildings with an efficient insulation.</jats:p

Thermal energy autonomy study for a reference house equipped with PV panels, a heat pump and PCM storage elements

Abstract Despite their rapid growth, renewable energies cannot provide energy on demand, which is an essential requirement for heating buildings. To this end, we developed heat exchangers with Phase Change Materials that allow the on-demand charge, storage and discharge of thermal energy. In this paper we evaluate the storage capacities needed to achieve thermal energy autonomy. An existing reference house, meteorological data from MeteoSwiss and solar radiation intensity were used to evaluate the thermal needs and the solar power production for the year 2019. To heat the building an air-water heat pump is preferably powered by solar energy. The calculations have been performed from October to March. Using 1200 litres of PCM, a thermal autonomy of 100% was achieved for March and October. In February, November and December, 24 days could not reach a thermal autonomy. For the month of January that was studied in detail 15 days are self-sufficient. By increasing the PCM volume to 2’600 litres 5 more days become self-sufficient. To achieve total building heating autonomy, seasonal storage is necessary.</jats:p