thermique

Thermique is a French term and concept referring to heat and to phenomena related to thermal energy. In physics and engineering, it encompasses the study of heat transfer, the behavior of systems as they exchange energy, and the processes by which heat is produced, transformed, or used. The word derives from thermo- (Greek) meaning heat, with the suffix -ique.

In thermodynamics, heat is the energy transferred due to a temperature difference. The main modes of heat transfer are conduction, convection, and radiation. Materials have thermal properties such as temperature, heat capacity, specific heat, thermal conductivity, and phase transitions. Temperature measures the average kinetic energy of microscopic constituents, while heat is the energy in transit between systems.

The fundamental principles include the first law, which expresses energy conservation: the change in internal energy of a system equals heat added minus work done. The second law introduces entropy and sets limits on the conversion of heat into work, explaining the direction of spontaneous processes and the operating principles of heat engines and refrigerators. The third law concerns behavior as temperature approaches absolute zero.

Applications of thermique span engineering and everyday life: heating and cooling of buildings, engines and power plants, electronics thermal management, food processing, and energy systems such as solar thermal and waste-heat recovery. Measurements rely on units such as joules and calories, and temperature scales such as Celsius and Kelvin.