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When unsaturated air is adiabatically saturated, which of the following properties decrease? 1. Dry bulb temperature 2. Wet bulb temperature 3. Relative Humidity 4. Specific Humidity

When unsaturated air is adiabatically saturated, which of the following properties decrease? 1. Dry bulb temperature 2. Wet bulb temperature 3. Relative Humidity 4. Specific Humidity Correct Answer 1 only 

Concept:

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An adiabatic saturation process is an adiabatic process in which an air and water vapor mixture with a relative humidity of less than 100% have liquid water added. Some of the water is evaporated into the mixture bringing it to the saturation process which is nothing but an adiabatic saturation process.

  • Evaporative cooling takes place along lines of constant wet-bulb temperature or enthalpy.
  • It is obtained during the process of adiabatic saturation, where there is the removal of sensible heat from the air and an equivalent amount of heat addition in the form of latent heat to it in the form of added water vapor.
  • This is because there is no change in the amount of energy in the air.
  • The energy is merely converted from sensible energy to latent energy.
  • The moisture content of the air increases as the water is evaporated which results in an increase in relative humidity along a line of constant wet-bulb temperature.

We can see from the figure mentioned above,

  • Wet-bulb temperature of the air during the adiabatic saturation process remains constant 
  • Dry bulb temperature decreases 
  • Specific humidity increases and
  • Relative humidity also increases.

Related Questions

Consider the following statements: 1. The relative humidity of air does not change with temperature as long as specific humidity remains constant. 2. Dew-point temperature is the temperature at which condensation begins when air is cooled at constant volume. 3. Saturated air passing over a water surface does not cause change of air temperature. 4. For saturated air, dry-bulb, wet-bulb and dew-point temperatures are identical. Which of the above statements are correct?
The wet bulb temperature is lower in dry air than in wet air at the same temperature. A dry bulb thermometer registers a higher temperature than a wet bulb thermometer except at __________ percent relative humidity.
Suppose saturated polar air has an air temperature and dew point of -10o C, and unsaturated desert air has an air temperature of 35o C and a dew point of 10o C. The desert air contains ______ water vapour and has a ________ relative humidity than the polar air.
If ouside air is to be conditioned from 60% relative humidity and 40 °C dry bulb temperature to 50% relative humidity and 24 °C dry bulb temperature, which psychromatic process would be required?
It is desired to condition the outside air from 70% relative humidity and 45°C dry bulb temperature to 50% relative humidity and 25°C dry bulb temperature (room condition). The practical arrangement will be
The bypass factor (B. P. F.) in case of sensible heating of air is (Where td₁ = Dry bulb temperature of air entering the heating coil, td₂ = Dry bulb temperature of air leaving the heating coil, and td₃ = Dry bulb temperature of heating coil)
The bypass factor, in case of sensible cooling of air, is given by (where td₁ = Dry bulb temperature of air entering the cooling coil, td₂ = Dry bulb temperature of air leaving the cooling coil, and td₃ = Dry bulb temperature of the cooling coil)
The bypass factor (B.P.F.) in case of sensible heating of air is (Where td1 = Dry bulb temperature of air entering the heating coil, td2 = Dry bulb temperature of air leaving the heating coil and td3 = Dry bulb temperature of heating coil)
The bypass factor, in case of sensible cooling of air, is given by (where td1 = Dry bulb temperature of air entering the cooling coil, td2 = Dry bulb temperature of air leaving the cooling coil and td3 = Dry bulb temperature of the cooling coil)
Relative humidity is given by (where pv = Partial pressure of water vapour, pb = Barometric pressure, ps = Pressure of saturated air, pd = Pressure at dry bulb temperature, pw = Saturation pressure corresponding to wet bulb temperature, and μ = Degree of saturation)