It also postulates that energy can be transferred from one thermodynamic system to another " walls ", especially adiabatic walls and non-adiabatic walls, defined as follows.
12.
It also postulates that energy can be transferred from one thermodynamic system to another " walls ", especially adiabatic walls and non-adiabatic walls, defined as follows.
13.
When some are not adiabatic, then the system is not adiabatically enclosed, though "'adiabatic transfer of energy as work "'can occur across the adiabatic walls.
14.
An adiabatic wall between the two systems is'permeable'only to energy transferred as work; at mechanical equilibrium the rates of transfer of energy as work between them are equal and opposite.
15.
On the other hand, according to Carath�odory ( 1909 ), there also exist non-adiabatic walls, which are postulated to be " permeable only to heat ", and are called diathermal.
16.
For convenience one may say that the adiabatic component was the sum of work done by the body through volume change through movement of the walls while the non-adiabatic wall was temporarily rendered adiabatic, and of isochoric adiabatic work.
17.
If several systems are free of adiabatic walls between each other, but are jointly isolated from the rest of the world, then they reach a state of multiple contact equilibrium, and they have a common temperature, a total internal energy, and a total entropy.
18.
Nevertheless, Carath�odory requires that his adiabatic walls shall be imagined to be flexible, and that the pressures on these flexible walls be adjusted and controlled externally so that the walls are not deformed, unless a process is undertaken in which work is transferred across the walls.
19.
If the adiabatic wall is more complicated, with a sort of leverage, having an area-ratio, then the pressures of the two systems in exchange equilibrium are in the inverse ratio of the volume exchange ratio; this keeps the zero balance of rates of transfer as work.
20.
This includes cases in which there is contact equilibrium between the system, and several subsystems in its surroundings, including separate connections with subsystems through walls that are permeable to the transfer of matter and internal energy as heat and allowing friction of passage of the transferred matter, but immovable, and separate connections through adiabatic walls with others, and separate connections through diathermic walls impermeable to matter with yet others.
