Universal Gas Law
The First Law
Always true:
For cycles:
For constant volume (no work done):
Work Done
Always true:
True for constant :
True for constant :
(PV is constant)
True when adiabatic & reversible:
(Isentropic)
Shaft Work
Constant Pressure
Constant Volume
Perfect, Adiabatic & Reversible (Isentropic)
is constant:
is constant:
is constant:
Enthalpy
Perfect Gases & Temperature
Change in energy, :
Change in enthalpy, :
Perfect gas constant, :
Perfect gas ratio, :
Steady Flow Energy Equation (SFEE)
Mass flow rate, :
Volume flow rate, :
is the density
is the speed
is the cross-sectional area of the duct
is the specific volume
Wet Vapour
Dryness fraction, :
Wet Property, :
Clausius’ Inequality
For a reversible cycle or process:
For an irreversible cycle of process:
Combining 1st & 2nd Laws
These equations are valid for both reversible and irreversible processes, as all quantities are properties.
Perfect Gas Processes
Again, these are applicable to both reversible and irreversible processes so long as the gases are perfect.
Efficiencies
General efficiency, :
Thermodynamic Efficiencies, :
Thermal (reversible) efficiency, :
Isentropic Efficiencies, 
Turbine/Engine

Compressor/Pump
