Types of System, Open System and isolated system

Types of System

    Control Mass System (Closed System)

1. Its a system of fixed mass with fixed identity. 
2. This type of system is usually referred to as "closed system".
   
3. There is no mass transfer across the system boundary. 
4. Energy transfer may take place into or out of the system. 

Fig 9.2   A Control Mass System or Closed System

    Control Volume System (Open System)

1. Its a system of  fixed volume.
2. This type of system is usually referred to as "open system” or a "control volume"
3. Mass transfer can take place across a control volume.
4. Energy transfer may also occur into or out of the system.
5. A control volume can be seen as  a fixed region across which mass and energy transfers are studied. 
6. Control Surface- Its the boundary of a control volume across which the transfer of both mass and energy takes place.
7. The mass of a control volume (open system) may or may not be fixed.
8. When the net influx of mass across the control surface equals  zero then the mass of the system is fixed and vice-versa.
9. The identity of mass in a control volume always changes unlike the case for a control mass system (closed system).
10. Most of the engineering devices, in general, represent an open system or control volume.

Example:-

• Heat exchanger - Fluid enters and leaves the system continuously with the transfer of heat across the system boundary. 
• Pump - A continuous flow of fluid takes place through the system with a transfer of mechanical energy from the surroundings to the system.

Fig 9.3  A Control Volume System or Open System

     Isolated System

1. Its a system of fixed mass with same identity and fixed energy.
2. No interaction of mass or energy takes place between the system and the surroundings.
3. In more informal words an isolated system is like a closed shop amidst a busy market.

Fig 9.4   An Isolated System