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. ⌠dq=⌠dw
  • For a closed system undergoing a change of state. Q=Δu+w
  • C_v=(∂u∕∂T)_r=(∂Q∕∂T) & C_p=(∂h∕∂T)_p=(∂Q∕∂T)_p where as [C_P-C_V=R]
  • For polytropic process the specific heat is C_n=C_v(r-n/1-n)
• First law appiled to Flow Process:
  • steady flow process :
  • m_i=m₀ where as ==> A₁C₁/V₁=A₂C₂/V₂
  • Variable flow process :
  • m_i-m_o=m_v
  • workdone in flow process = –₁∫²vdp [.^..Q=Δh-₁∫²vdp]
• Second law of thermodynamics:
  • Efficiency of heat engine . n=Q₁-Q₂/Q₁=W_net/Q₁ <100%

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