Thermodynamic System and its types

What is Thermodynamics System?

It is a quantity of matter or a region in space upon which study of matter take palace.

What is surrounding ?

Everything external to the system is known as Surrounding.

What is Boundary ?

• The layer which separate system and surrounding is known as Boundary.
• The boundary may be either fixed or movable.
• System and surrounding together comprise universe.

Types of System :-

      There are three types of System :-

1) Closed system or Control mass  System :-

• In this system there are no mass transfer across system boundary but energy may be transfer.
• Ex :- Battery, 
  
• It is also known as Control Mass System or Fixed Mass System, because mass of this system is always constant or fixed.
• Identity of this system is fixed -i.e- same molecules is present every time in system.

2) Open system or Control Volume System :-

• In this system Mass Transfer occur across the boundary but energy may or may not be transfer.
• Ex :- Air Compressor, Engine Piston and Cylinder etc.
  
• It has fixed volume hence it is also known as Control Volume System.
• It is a Variable Mass System.
• The identity of this System is Variable.

                     Ex :- If  a water tank  contain two pipe in which one is used for fill the tank and another is used to empty the tank. If both pipe is open simultaneously and flow rate through both pipe is same then in this case volume of water inside tank is fixed (because flow rate through both pipe is same) but identity is variable (because new water molecules enter from one pipe and another water molecules leaving from other pipe) hence It is a Open System.

• Most of the engineering devices are Open System.

3) Isolated System :-

• The system which doesn't exchange the mass or energy with surrounding is known as Isolated System.
• It is a fixed mass and fixed energy system.
• Ex :- Thermos.
  
• The universe is consider as isolated system.
• The entropy of isolated system always tends toward the maximum.