Wet-Bulb temperature

Wet-Bulb temperature :

Wet bulb temperature

If we have to study evaporative cooling, psychrometry, thermodynamics, or just work in a place where there are cooling towers, the wet bulb temperature and dry bulb. Often confused and not clearly understand the concept.
The wet bulb temperature is a temperature measurement type physical properties of a system consisting of a mixture of gas and vapor (usually air and water vapor). The wet bulb temperature is the lowest temperature that can be reached using the evaporation of water only

Generally, the wet-bulb temperature is measured by a standard thermometer located under the shade, but with its bulb wrapped in a cotton wick (a porous, absorbent or similar material) whose bottom is submerged in a container of water. Using a system fan is exposed to a constant air flow of approximately 3 m / s, which causes the water rises by capillary action along the wick to evaporate relatively easily.Evaporation processes heat absorption , which causes the bulb to cool down gradually. Bulb temperature is lowered so that the air that surrounds (contained in the pores of the wick) is completely saturated. A value representing the wet-bulb temperature is then obtained in the thermometer.

when You taking it to everyday things, is the temperature that we feel when we have wet skin and expose ourselves to moving air.Temperaturaes Such an indicator the amount of moisture that is present in the air.
Then the wet bulb temperature is the minimum temperature that can be reached by evaporative cooling. For a given air at a known pressure and dry bulb temperature (normal temperature we measure with a thermometer), the wet bulb temperature corresponding to relative humidity, dew point, and other properties.
 When air is below the saturation level, that is, when the relative humidity is below 100%, the wet bulb temperature is always lower than the dry bulb temperature. In this sense, the wet bulb temperature expressed indirectly the humidity , because while the lower the relative humidity the water easily evaporates and more intense are the processes of heat loss. This also means that in dry climates the relative difference between the simultaneous temperature dry bulb and wet bulb is always greater than in humid climates. On the other hand, the difference between the two temperatures is an indication of the potential of evaporative cooling systems: if the difference is big these systems are usually quite efficient if its efficiency is very small decreases drastically.
The human body uses this principle (evaporative cooling) through perspiration. thats why high humidity will cause discomfort for human body .

 

 

Wet-bulb Temperature have direct relation with the relative humidity please check Psychrometric Chart