Dry air evaporates more water off the wick, so wet bulb drops further below dry bulb; at 100 percent relative humidity the two are equal. Wet bulb tracks the enthalpy of air closely, which is why indoor wet bulb is used in superheat charging charts and why cooling tower performance is rated against entering wet bulb.
Indoor wet bulb is 63, outdoor 92 dry bulb, chart says target superheat 9, we're sitting at 25.
Also heard as
- WB
- wet-bulb temperature
Related terms
Dry bulb
Plain air temperature as an ordinary thermometer reads it, kept dry and out of direct sun.
Sling psych
Shop name for a sling psychrometer, or any handheld instrument used to read wet bulb and dry bulb.
Enthalpy
The total heat content of moist air, sensible plus latent, in Btu per pound of dry air.
Approach
The temperature gap between a fluid leaving a heat exchanger and the fluid or condition it is being brought toward.
Cooling tower
Equipment that cools condenser water by evaporating a small part of it into an airstream.