Moisture Holding Capacity Air

Overview

Engineering reference data for Moisture Holding Capacity Air in air psychrometrics.

Key Formulas

Humidity Ratio

$\omega = 0.622 \frac{P_v}{P_a}$

Mass of water vapor per mass of dry air.

Relative Humidity

$\phi = \frac{P_v}{P_{vs}} \times 100\%$

Ratio of actual to saturation vapor pressure.

Wet Bulb Temperature

$T_{wb} = T_{db} - \frac{P_{vs} - P_v}{\gamma}$

Temperature measured by wet-bulb thermometer.

Enthalpy of Moist Air

$h = c_p T + \omega h_g$

Sensible + latent heat per unit mass of dry air.

Variables

Temperature Effects on Moisture Capacity

The moisture holding capacity of air increases dramatically with temperature, a relationship critical for applications like drying processes. For instance, the capacity at 100°F (38°C) is roughly 10 times that at 30°F (~0°C). This significant enhancement in moisture transport suggests that increasing air temperature in dryers can improve energy efficiency, as the gains in moisture carrying capacity typically outweigh the costs of heating the air.

References

• Original Source