Important Thermodynamic Equations and Formulas
Thermodynamics is filled with equations and formulas. Here’s a list of the most important ones you need to do the calculations necessary for solving thermodynamics problems.

Combustion equations:

Airfuel ratio:

Hydrocarbon fuel combustion reaction:


Compressibility calculations:

Compressibility factor Z: Pv = ZRT

Reduced temperature:

Reduced pressure:

Pseudoreduced specific volume:


Efficiency equations:

Thermal efficiency:

Coefficient of performance (refrigerator):

Coefficient of performance (heat pump):


Energy equations:

Entropy equations:

Entropy change for ideal gas, constant specific heat:

Entropy change for ideal gas, variable specific heat:

Irreversibility for a process:


Idealgas formulas:

Idealgas law: Pv = RT

Gas constant:

Ratio of specific heats:

Isentropic process for ideal gas:


Moist air properties:

Relative humidity:

Specific humidity:


Properties of mixtures:

Quality liquidvapor mixture:

Saturated mixture property, y: y = y_{f} + x · y_{fg}_{}


Work calculations:

Isobaric process: W_{b} = P_{0}(V_{2} – V_{1})

Polytropic process:

Isothermal process of an ideal gas:

Shaft power:

Spring work:
