Thermodynamics For Dummies Cheat Sheet

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 = y_f + x · y_fg

Work calculations:

• Isobaric process: W_b = P₀(V₂ – V₁)

• Polytropic process:

  

• Isothermal process of an ideal gas:

  

• Shaft power:

  

• Spring work:

  

Acceleration: 1 m/s² = 100 cm/s²

Area: 1 m² = 10⁴ cm² = 10⁶ mm²

Density: 1 g/cm³ = 1 kg/L = 1,000 kg/m³

Energy, heat, work, internal energy, enthalpy: 1 kJ = 1,000 J = 1,000 N·m = 1 kPa·m³

1 kJ/kg = 1,000 m²/s²

Force: 1 N = 1 kg·m/s²

Length: 1 m = 100 cm = 1,000 mm

Mass: 1 kg = 1,000 g

Power, heat transfer rate: 1 W = 1 J/s, 1 kW = 1,000 W

Pressure: 1 Pa = 1 N/m², 1 kPa = 1,000 kPa, 1 MPa = 1,000 kPa

1 atmosphere (atm) = 101.325 kPa

Specific heat, entropy: 1 kJ/kg · °C = 1 kJ/kg · K = 1 J/g·°C

Specific volume: 1 m³/kg = 1,000 L/kg = 1,000 cm³/kg

Temperature: T(K) = T(°C) + 273.15, T(°C) = (5/9) T(°F) – 32, T(°F) = (9/5) T(°C) + 32

Velocity: 1m/s = 3.6 km/hr

Volume: 1 m³ = 1,000 L = 10⁶ cm³

Acceleration of gravity: g = 9.81 m/s²

Standard atmospheric pressure: 1 atm = 101.3 kPa

Universal gas constant: