- A closed system is also known as control mass. It consists of fixed amount of mass.
- No mass can cross its boundaries
- That is no mass can enter or leave a closed system
- Examples: Piston-cylinder arrangement, oven in the kitchen
- An open system is a properly selected region in space
- It is also called control volume
- Both mass and energy can cross the boundary
- Examples: compressor, turbine, nozzle, water heater, car radiator, etc