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Homework Help: Simple humidifying process

  1. Nov 22, 2013 #1
    1. The problem statement, all variables and given/known data

    Consider Simple humidifying process. Atmospheric air enter at a volume flow rate of 3000 m3/h at 25°C and 10% relative humidity (A). Then is humidified to 60% relative humidity (B) by adding saturated steam at atmospheric pressure. The density of atmospheric air is 1.18 kg/m3

    2. Relevant equations
    a) Plot the whole process on psychometric chart?
    b) What is the final temperature of air?
    c)What is mass flow rate of water added
    d) What is the total heat added by the steam

    3. The attempt at a solution

    I have plotted the humidifying process on the psychometric chart by following the vertical line which corresponds to 25°c. Using the vertical line, I marked the points where 10% & 60% relative humidity intersect the line, then from the points I drew a diagonal line to obtain moisture content. (A) = 0.002
    (B) = 0.0125

    Using Mw = V * ρ (B - A) =

    Mw being the mass of water added
    V = 3000 m3/h
    ρ = 1.18 kg/m3
    A = 0.002
    B = 0.0125

    =3000/3600 x 1.184(0.0125 - 0.002) = 0.01036 kg/s = 37.8296 kg/h

    I know that heat is being added to the the air, by the steam but the photometric chart plot does not show any change in in the final temperature. How can I find the final temperature?
  2. jcsd
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