zártrendszer

A zártrendszer, or closed system, is a concept originating from thermodynamics and widely used in various scientific and engineering fields. In its most fundamental definition, a closed system is one that does not exchange matter with its surroundings, but it can exchange energy. This is distinct from an isolated system, which exchanges neither matter nor energy, and an open system, which exchanges both.

The distinction between these system types is crucial for analyzing physical processes. For example, in a sealed container of water that is heated, the water represents a closed system. Heat energy can be added to or removed from the water, but no water vapor escapes, nor does any external substance enter. If the container were left open to the atmosphere, it would be an open system, as water vapor could escape and air could enter.

The concept of a closed system is often an idealization used to simplify complex scenarios. Real-world systems may approximate closed systems under specific conditions for limited periods. Understanding whether a system can be treated as closed allows scientists to apply specific laws and equations, such as the first law of thermodynamics, which states that the change in internal energy of a closed system is equal to the heat added to the system minus the work done by the system. This principle is fundamental to understanding energy transformations in engines, chemical reactions, and biological processes.