In Business, What Is a Closed System?

In thermodynamics, there is no material exchange with the outside world (environment), but a system with energy exchange is called a closed system.

A system that has only energy exchange with the environment without material exchange is called a closed system. ^[1]

Heat and work have clear meaning only for processes that occur in closed systems. The amount of heat and work is closely related to the process. Once the process is over, there is no mention of the existence of heat and work. They are not

For a static closed system, without considering the special external force field (such as centrifugal force field, electromagnetic field, etc.), the change from the initial state (1) to the final state (2), this change can be achieved through different processes, experiments The results show that the magnitudes of W and Q corresponding to each process may be different, but the (Q + W) magnitudes of each process are equal. This means that after the system changes state, there must be a change in the state function as U, U is called thermodynamic energy (internal energy) or internal energy (unit: J).

U =

= Q + W

If the state of the system changes only infinitely, then

dU = Q + W

and are the mathematical expressions of the first law of thermodynamics used in closed systems, and they are also applicable to isolated systems. They show the quantitative relationship between the conversion of thermodynamic energy, heat and work. ^[2]