HVAC & Refrigeration
Advanced

Humidity Ratio

Mass of water vapour per unit mass of dry air.

Formula

w=0.622pvp−pvw = 0.622 \frac{p_v}{p - p_v}

Live Calculator

Members

Variables

wHumidity ratio (kg/kg)
p_vVapour pressure (Pa)
pTotal pressure (Pa)

Example

p_v=1700, p=101325: w ≈ 0.0106 kg/kg

Did You Know?

The constant 0.622 is the ratio of the molar masses of water and dry air.

hvachumiditypsychrometrics

Share this formula

More in HVAC & Refrigeration

View all

Sensible Heat Load

Basic

Heat needed to change air or water temperature without a phase change.

Latent Heat Load

Intermediate

Heat absorbed or released when moisture condenses or evaporates — the hidden load air conditioners fight.

Coefficient of Performance (Cooling)

Intermediate

Cooling delivered per unit of work input — higher is more efficient.

Energy Efficiency Ratio (EER)

Basic

Cooling capacity in BTU/h per watt of power — a common AC rating.

Refrigeration Tons

Basic

Cooling capacity in tons, where one ton removes 12,000 BTU/h.

Airflow (Sensible)

Intermediate

Air volume flow needed to carry a sensible heat load (imperial units).