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Thermodynamics Processes

Thermodynamics Processes are the processes that take place when a system changes its thermodynamic state. To know more about System and Thermodynamics State view my previous post on Thermodynamics.
Thermodynamics Processes

#Types of Thermodynamics processes


1. Cyclic Process - When the system undergoes a thermodynamic process in which final and initial state of a system are identical then that process is called a cyclic process. 
In these processes, a system can undergo energy transfer with the surrounding because it can follow different paths to attain the same thermodynamic state.
Thermodynamics Processes | cyclic

2. Reversible Process - A process which can be reversed to its initial state by following the same path which it followed to reach its final state is known as Reversible Process.
 OR
A process that can be reversed to its initial state without affecting the system and surrounding is known as Reversible Process.
Thermodynamics Processes | Reversible


3. Irreversible Process - A Process which that cannot be reversed to its initial without affecting the system and surrounding.
Thermodynamics Proceses | Irreversible

#Causes of Irreversibility

  • Irreversibility can occur due to friction which is presents in the path of the process.
  • If the process is to fast that a system fails to thermodynamic equilibriums during the process.

#Thermodynamic Equilibrium

A system is said to be in thermodynamic equilibrium if it attains Mechanical Equilibrium, Chemical Equilibrium, and Thermal Equilibrium.
Now I will explain to you what are these equilibriums which are necessary for a system to attain a Thermodynamic Equilibrium.

A. Mechanical Equilibrium - When the net effect of all the forces acting on a system due to surrounding is zero then is said to be in mechanical equilibrium with the surrounding.

B. Chemical Equilibrium - When no chemical reactions are taking place inside a system, then a system is said to be in chemical equilibrium with the surrounding.

C. Thermal Equilibrium - When the system and the surrounding have the same temperature, then the system is said to be in thermal equilibrium with the surrounding.

Now we discuss the third process which is Quasi-Static Process, the most important one.

3. Quasi-Static Process - It consists of two words, "Quasi" which means "Almost" and "Static" means "Rest", So we can define it as a process which is very-very slow like there is no change taking place in its thermodynamic state.
It's a hypothetical process due to its slow nature. It will take an infinite amount of time for its completion.

#Quasi-Static, Reversible and Irreversible Processes

⭐For a Reversible Process, a defined path must be present because only then a process can be reversed and a path consists of states or thermodynamic equilibriums which can be achieved only when a process is very very slow which a system takes time to attain a thermodynamic equilibrium. 
So we can say "All Reversible Processes are Quasi-Static Processes".

NOTE - 
a - A Reversible Process has maximum efficiency and hence all other processes are compared with this process.
b - A Reversible Process cannot be practically performed as they are very slow in nature.

⭐A Quasi-Static Process with friction in its path is an Irreversible in nature.
⭐A Non-Quasi-Static Process(fast in nature) is also an Irreversible Process.

NOTE - 
a - We in Thermodynamics represents Reversible Process by a line and Irreversible Process by dotted line.
b - We learn Thermodynamics by drawing Reversible Process because an Irreversible cannot be drawn on a paper.

4. Isochoric Process - A process during which pressure of the system remains constant.
Thermodynamics Processes | Isochoric


5. Isobaric Process - A process during which the volume of the system remains constant.
Thermodynamics Processes | Isobaric


6. Isothermal Process - A process during which the temperature of the system remains constant. It is governed by - 
PV = Constant
Thermodynamics Processes | Isothermal

7. Adiabatic Process - A process in which there is no heat transfer from the system to the surrounding and vice-versa. It is governed by - 
PV^Y  = Constant
Thermodynamics Processes | Adiabatic

8. Polytropic Process - A process which occurs in between the Isothermal and Adiabatic Processes. It is governed by - 
PV^n = Constant
Thermodynamics Processes | Polytropic
Where, 
P = Pressure
V = Volume
Y = Adiabatic Constant
n = Polytropic Index






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