Thermodynamic System: It is that part of the universe which is under consideration. There are following types of thermodynamics systems.
- Open system: In this types of system the transfer of energy as well as the mass takes place between the system and the surroundings. eg. Air compressor.
- Closed system: In closed system there is no transfer of mass across the boundary but the transfer of energy may take place between the system and the surroundings. eg. Piston-cylinder arrangement.
- Isolated system: This system is completely isolated from their environment. In this system neither the energy nor the mass is transferred between system and the surroundings takes place. eg. Fluid contained in a thermos flask.
Surroundings: Space or matter outside of a thermodynamic system is called surroundings or environment.
Boundary: The envelope which separates the thermodynamic system and surroundings is called boundary.
Universe: The system and the surroundings together form a universe