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Psychrometric Calculator
Calculate psychrometric properties of moist air from dry bulb temperature and relative humidity. Get dew point, wet bulb, humidity ratio, enthalpy, and vapour pressure.
Understanding Psychrometrics
Psychrometrics is the study of the thermodynamic properties of moist air. The key properties are: dry bulb temperature (actual air temperature), wet bulb temperature (temperature at 100% RH), dew point (temperature at which condensation begins), humidity ratio (mass of water per mass of dry air), and enthalpy (total heat content).
These properties are essential for sizing cooling coils, dehumidifiers, and AHUs. A psychrometric chart visualises the relationships between these properties.
Frequently Asked Questions
What is the difference between dry bulb and wet bulb temperature?
Dry bulb is the actual air temperature. Wet bulb is the temperature a thermometer reads when wrapped in a wet wick and exposed to moving air — it's always lower than dry bulb (unless RH = 100%).
What is dew point?
Dew point is the temperature at which water vapour in the air begins to condense. If the air temperature drops below the dew point, condensation forms on surfaces.
What is enthalpy in HVAC?
Enthalpy is the total heat content of air, including both sensible heat (temperature) and latent heat (moisture). It's measured in kJ per kg of dry air and is used for coil load calculations.
Psychrometric Calculator
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