Wet Bulb Dry Bulb

The knowledge of only two of these values is enough to determine the state of the moist air including the content of water vapor and the sensible and latent energy enthalpy in the air.

Wet bulb dry bulb.

Wet bulb temperature is the lowest temperature to which air can be cooled by the evaporation of water into the air at a constant pressure. The dry bulb temperature is the ambient temperature. At lower humidity the wet bulb temperature is lower than dry bulb temperature because of evaporative cooling. By definition wet bulb temperature is the lowest temperature a portion of air can acquire by evaporative cooling only.

Relative humidity is measured using a device called a sling psychrometer this consists of 2 side by side conventional thermometers one of which the wet bulb thermometer has a wetted wick placed at the bottom the other the dry bulb thermometer has no wetted wick. When the psychrometer is swung around by its attached chain or handle the air causes the water on the wick to evaporate which. Combining the dry bulb and wet bulb temperature in a psychrometric diagram or mollier chart gives the state of the humid air. At 100 relative humidity the wet bulb temperature is equal to the air temperature dry bulb temperature.

The dry bulb wet bulb and dew point temperatures are important to determine the state of humid air. The wet bulb temperature wbt is the temperature read by a thermometer covered in water soaked cloth wet bulb thermometer over which air is passed. It is therefore measured by wrapping a wet wick around the bulb of a thermometer and the measured temperature corresponds to the wet bulb temperature. It includes a dry bulb thermometer a wet bulb thermometer and a psychrometric chart a graph that plots the relationships between the dry and wet bulb temperature relative humidity and dew point at constant pressure.