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Psychometry

Psychrometry: is the study of moist air. Before starting study of refrigeration process everyone should take a basic knowledge of Psychrometry. It is consist of these topics,
i . DBT (Dry  Bulb temperature)
ii. WBT (Wet Bulb temperature)
iii. DPT (Dew Point temperature)
iv. Specific Humidity
v. Relative Humidity
vi. Degree of Saturation

 DBT: Dry bulb temperature is the normal temperature of the air in room. When a thermometer gives normal temperature in atmospheric or ambient, that is called DBT.

 WBT: Wet Bulb Temperature is different from DBT. From it's name we get something different. If  Wet something like a Wet clothes is wrapped in the sensing side of the thermometer than which reading it will give, that is known is WBT. The wet clothes moisture will consume by normal air or atmospheric air. Air is always ready to consume moisture if it's Relative Humidity ( RH) is less than 100%. Relative Humidity is the term, what represent the amount of moisture are in the air. In normal condition DBT is always less than WBT. Suppose, If DBT gives 30 degree the WBT will be less than 30 degree.When Relative Humidity is 100%, than DBT=WBT.

 Specific Humidity: It is called Absolute or Humidity ratio. If a simple volume of air take from atmospheric air. There we can observe both air and moisture. Cause moisture is always present in air.The ratio of mass of vapor upon mass of  air on that taken portion volume is called Specific Humidity. It is denoted by w. Specific Humidity:
                                                                   ( Mass of Vapor: Mass of Air)

Degree of Saturation: In normal condition moisture of air stay or water vapor of air stay in super-heated  and unsaturated condition. That means it can absorb more moisture. It can absorb moisture in constant temperature. The air can absorb  moisture till reaching the saturated line. After reaching the saturated line it is saturated condition. If more moisture are added that condition than it changes its phase.
Dew Point Temperature: When moisture or water vapor having in a particular temperature in super-heated unsaturated condition. If the temperature is decreasing it will reaches saturated line. In this point it could not contain same moisture from that decreasing point. Now if it change the phase the moisture fall look dew. The point which dew start it is called Dew Point temperature.
Relative Humidity: How much amount of moisture air contain is understand by Relative Humidity.

  
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