Psychrometric Chart

This Demonstration of a psychrometric chart calculates the relative humidity

RH

[%], absolute humidity

AH

[kg water/kg dry air], dry bulb temperature

DBT

[ºC], and specific volume SV [m³/kg dry air] for different pairs of temperature and absolute humidity at a pressure of 101.325 kPa.

You can drag the locator to see values at points on the saturation line and points with relative humidity less than 100%. The blue line represents the saturated air; the purple lines are the lines with relative humidity equal to 80%, 60%, 40%, 20%, and 10%.

The equations used to simulate this psychrometric chart are:

RH=

100×101325AH

(0.22+AH)exp0.43-

834.27

DBT+273.15

-5.17log(DBT+273.15)

,

SV=

287.05

101325

(DBT+273.15)(1+1.6078AH)

.