 Important Thermodynamic Equations and Formulas - dummies

# 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:

• Air-fuel ratio: • Hydrocarbon fuel combustion reaction: • Compressibility calculations:

• Compressibility factor Z: Pv = ZRT

• Reduced temperature: • Reduced pressure: • Pseudo-reduced 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: • Ideal-gas formulas:

• Ideal-gas 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 liquid-vapor mixture: • Saturated mixture property, y: y = yf + x · yfg

• Work calculations:

• Isobaric process: Wb = P0(V2 – V1)

• Polytropic process: • Isothermal process of an ideal gas: • Shaft power: • Spring work: 