How to Use the Calculator
- Enter the temperature of the air in degrees Celsius (°C).
- Enter the relative humidity of the air as a percentage (%).
- Enter the atmospheric pressure in kilopascals (kPa). The default value is 101.325 kPa (standard atmospheric pressure).
- Click the "Calculate" button to compute the enthalpy of the moist air.
- The result will be displayed in kilojoules per kilogram (kJ/kg).
Working Principle
The Air Enthalpy Calculator calculates the enthalpy of moist air using the following formula:
h = h_d + (h_g - h_d) * φ / 100
Where:
- h is the enthalpy of moist air (kJ/kg)
- h_d is the enthalpy of dry air (kJ/kg), calculated as 1.006 * T + 0.287 * T * ln(es/101.325)
- h_g is the enthalpy of saturated water vapor (kJ/kg), calculated as 2501 + 1.88 * T + 0.287 * T * ln(es/101.325)
- φ is the relative humidity of the air (%)
- es is the saturation vapor pressure (Pa), calculated using the Magnus formula
- T is the absolute temperature (K)
Applications
The Air Enthalpy Calculator is useful in various fields such as:
- HVAC (Heating, Ventilation, and Air Conditioning) design and analysis
- Weather forecasting
- Industrial processes involving moist air
- Building energy efficiency calculations