Thermodynamic system

In thermodynamics, a thermodynamic system, originally called a working substance, is defined as that part of the universe that is under consideration. A real or imaginary boundary separates the system from the rest of the universe, which is referred to as the environment or surroundings (sometimes called a reservoir.) A useful classification of thermodynamic systems is based on the nature of the boundary and the quantities flowing through it, such as matter, energy, work, heat, and entropy. A system can be anything, for example a cylinder, a solution in a test tube, a living organism, or a planet, etc.

Thermodynamic System Media

• 

  Properties of isolated, closed, and open thermodynamic systems in exchanging energy and matter

• 

  Alternative to file:System boundary.svg, for display "flows/fluxes by arrows", avoiding representation mistakes.

• 

  Carnot engine diagram (modern) – where heat flows from a high temperature TH furnace through the fluid of the "working body" (working substance) and into the cold sink TC, thus forcing the working substance to do mechanical work W on the surroundings, via cycles of contractions and expansions.