Thermodynamics

Jump to: navigation, searchAnnotated color version of the original 1824 Carnot heat engine showing the hot body (boiler), working body (system), and cold body, the letters labeled according to the stopping points in Carnot cycle. The thermodynamic system, or "system" in the original steam engine sense of the word, is one of three bodies that comprise the basic heat engine. The working body (system) is typically steam, although it can be any physical body of the universe; the other two being the hot body (typically a boiler, heated by fire) and the cold body (typically a spray of cold water, from a nearby stream). This is the basic model in thermodynamics, whose operation is defined by the seven-step Carnot cycle, added to which other factors, such as electrical work, chemical work, elongation work can be quantified by their modification to the change in the internal energy of the working body or "system".^[1]

In science, thermodynamics (from the Greek θέρμη therme, meaning "heat"^[2] and δύναμις, dynamis, meaning "power") is the study of energy conversion between heat and mechanical work, and subsequently the macroscopic variables such as temperature, volume and pressure. The first to give a concise definition of the subject was Scottish physicist William Thomson who in 1854 stated that:^[3]

“Thermo-dynamics is the subject of the relation of heat to forces acting between contiguous parts of bodies, and the relation of heat to electrical agency.”

Two derivatives of thermodynamics to emerge in the decades to follow include: statistical thermodynamics (or statistical mechanics) (1860), a subject concerned with statistical predictions of the collective motion of particles from their microscopic behavior, and chemical thermodynamics (1873), a subject concerned with the nature of the role of entropy in the process of chemical reaction.^[4][5][6] Historically, thermodynamics developed out of a need to increase the efficiency of early steam engines, particularly through the work of French physicist Sadi Carnot (1824) who believed that engine efficiency was the key that could help France win the Napoleonic War