# THERMODYNAMICS

Thermodynamic system and control volume :

A Thermodynamic system is defined as a “quantity of matter or a region in space upon which attention is concentrated in the analysis of a problem“.

The system is separated from the surroundings by the system boundary. The boundary may be either fixed or moving. A system and its surroundings together comprise a universe. Everything external to the system is called the surroundings or the environment.

Thermodynamic Equilibrium: A system is said to exist in a state of thermodynamic equilibrium when no change in any macroscopic property is registered if the system is isolated from its surroundings.

A system will be in a state of thermodynamic equilibrium if the conditions for the following three types of equilibrium are satisfied:

a) Mechanical equilibrium

b)Chemical equilibrium

c) Thermal equilibrium

BASIC CONCEPTS AND FORMULAS

• Isolated system: Internal Energry of system remain constant if no work. [...Fixed mass, Fixed energy]
• Displacement work:
• (dw=pdv) whereas dQ=dU+dw
• here dQ is energy
• First law of Thermodynamics:
• For a closed system undergoing a cycle. âŒ dq=âŒ dw
• For a closed system undergoing a change of state. Q=Î”u+w
• Cv=(âˆ‚uâˆ•âˆ‚T)r=(âˆ‚Qâˆ•âˆ‚T) & Cp=(âˆ‚hâˆ•âˆ‚T)p=(âˆ‚Qâˆ•âˆ‚T)p where as [CP-CV=R]
• For polytropic process the specific heat is Cn=Cv(r-n/1-n)
• First law appiled to Flow Process:
• mi=m0 where as ==> A1C1/V1=A2C2/V2
• Variable flow process :
• mi-mo=mv
• workdone in flow process = –1âˆ«2vdp [...Q=Î”h-1âˆ«2vdp]
• Second law of thermodynamics:
• Efficiency of heat engine . n=Q1-Q2/Q1=Wnet/Q1 <100%

For more detailed information about thermodynamics formulas and definitions and examples..Thermodynamics – Simple English Wikipedia, the free encyclopedia