Types of Thermodynamics system | Open Thermodynamics System | Close Thermodynamic Systems | Thermodynamic System Surrounding And Boundary

Thermodynamic system Definition:

If a quantity of matter or region in space is taken under consideration for analysis then it is defined as thermodynamic system. Example of thermodynamic system is piston-cylinder assembly. 

Thermodynamic system surroundings and boundary

Boundary:

Thermodynamic system is identified by a boundary around the system. 

There are two types of boundary

• Real boundary
• Imaginary boundary

Surroundings:

Everything which is outside of the system boundary is called surroundings. Surroundings are outside of the system.

Universe:

 Thermodynamic system surrounding and boundary together is called universe. Universe includes all parts of system and surroundings.

So, 

Universe = Surroundings + Boundary

Thermodynamics-system-surroundings-boundary

Types of thermodynamic systems

There are three types of thermodynamic systems by transfers of mass and energy which is

• Open system
• Closed system
• Isolated system

Open thermodynamic system:

        The mass transfer and energy transfer takes place at the system boundary that type of system is called open thermodynamics system.

        So, open thermodynamics system is allowing the transfer of mass and energy both.

        Turbine and I.C. engines are open thermodynamic systems are examples of thermodynamics system.

Closed thermodynamics system:

 Closed thermodynamic system in which only energy transfers at its boundary. Such kinds of systems have not any mass transfers.

          So, closed thermodynamics system allows only the transfer of energy.

Best example of closed thermodynamic system is heated water in a closed pan because in that type of heated water energy (In form of heat) is coming from outside of the system. Another example of a closed thermodynamic system is pressure cooker.

Isolated thermodynamic system:

          In isolated system neither mass nor energy transfer across system boundary.

For the example of isolated thermodynamic system we can take perfectly insulated thermos flask because thermos flask is not transfer the energy or mass in any way.

Isolated thermodynamic system transfers neither energy nor mass at its boundary. That type of system is fully isolated from Surroundings.

Laws of thermodynamics

The law of thermodynamics defines physical quantities of thermodynamic system. There are four laws of thermodynamics.

Zeroth law of Thermodynamics:

Zeroth law of thermodynamics states that if two bodies (A & B) are in thermal equilibrium with a third body (C) separately then the two bodies (A & B) shall also be in thermal equilibrium with each other.

Zeroth law of thermodynamics is principal of temperature measurement.                     For understanding see the diagram.

zeroth-law-of-thermodynamics

In the diagram body A and B is in thermal equilibrium with body C separately, by first law both body A and B are in thermal equilibrium state with each other.

First law of thermodynamics:

First law of thermodynamics provides relationship between the various forms of energy and energy interaction. The law states that energy can neither be created nor destroyed, it can be only converted one form to another form.

First law is expressed as

Change in total energy (ΔE) = net energy transferred as heat and work (Q-W)

Change in total energy is ΔE, which is summation of various energies like kinetic energy, internal energy, potential energy etc.

In any closed system mass transfer is zero so potential energy and kinetic energy is zero. Hence there is only internal energy ΔU.

For closed thermodynamic system ΔU = Q – W.

For any type of cyclic process change in energy is always zero so, first law for cyclic process is Q-W=0.

Second law of thermodynamics:

Rudolph Julius Emmanuel Clausius presented first law of thermodynamics in 1850 which is termed as Clausius law for thermodynamics first law, Lord Kelvin and Max Plank also came up with thermodynamics second law which is termed as Kelvin-Plank statement for thermodynamics second law. Thus, there are two statements in thermodynamics first law.

Clausius Statement:

It is impossible to have a device that while operating in a cycle produces no effect other than transfer of heat from a body at lower temperature to a body at higher temperature.

OR

Heat itself cannot floe from a low temperature body to a high temperature body.

Kelvin-Plank statement:

It is impossible for a device operating in a cycle to produce net work while exchanging heat with bodies at single fixed temperature.

Above both statements are for second law of thermodynamics.

Third law of thermodynamics:

The third law of thermodynamic is regarding the properties of closed thermodynamic system which is in thermal equilibrium state.

Third law of thermodynamics states that “The entropy of a system approaches a constant value as its temperature approaches to absolute zero.”