psychrometrics Archives - Chemical Engineering Site https://chemicalengineeringsite.in/tag/psychrometrics/ For Chemical Engineers Mon, 15 Sep 2025 15:05:15 +0000 en-US hourly 1 https://wordpress.org/?v=6.9.4 Dew Point & Psychrometrics Calculator https://chemicalengineeringsite.in/dew-point-psychrometrics-calculator/ Mon, 15 Sep 2025 15:05:12 +0000 https://chemicalengineeringsite.in/?p=4093 Dew Point & Psychrometrics Calculator Enter dry-bulb temperature, relative humidity, and pressure. Calculates saturation vapor pressure, vapor/air partial pressures, humidity ratio, dry-air density, dew point, and wet-bulb. Export to Excel with live formulas. Dry-bulb Temperature °C Relative Humidity % Atmospheric Pressure Pabaratm Calculate 📊 Export Excel Reset Copy Saturation vapor pressure (at dry-bulb) – Pa […]

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Dew Point & Psychrometrics Calculator

Enter dry-bulb temperature, relative humidity, and pressure. Calculates saturation vapor pressure, vapor/air partial pressures, humidity ratio, dry-air density, dew point, and wet-bulb. Export to Excel with live formulas.

Saturation vapor pressure (at dry-bulb)
– Pa
Partial pressure of water vapor
– Pa
Partial pressure of dry air
– Pa
Humidity ratio
– kg/kgdry air
Dry air density
– kg/m³
Dew point temperature
– °C
Wet-bulb temperature (Stull)
– °C
Formula & unit notes
  • Saturation vapor pressure (Buck 1981; over water): e_s(T) = 611.21 · EXP((18.678 − T/234.5) · (T/(257.14 + T))) [Pa], T in °C.
  • Actual vapor pressure: p_v = (RH/100) · e_s.
  • Dry-air partial pressure: p_da = p_total − p_v.
  • Humidity ratio: w = 0.621945 · p_v / p_da (kg/kg dry air).
  • Dry-air density: ρ_da = p_da / (R_da · (T+273.15)), R_da = 287.058 J·kg⁻¹·K⁻¹.
  • Dew point (inverse Buck/Magnus): T_dp = (257.14·LN(p_v/611.21)) / (18.678 − LN(p_v/611.21)) [°C].
  • Wet-bulb (approximation): Stull (2011).

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