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Adiabatic mixing of airstreams

  1. Jan 6, 2010 #1
    I'm having a lot of trouble with an adiabatic mixing process.
    This is what I know:
    There's an airstream coming from outside and its temperature is T1=5 'C, its relative humidity being [tex]\varphi[/tex]1= 90% at a rate of 20 m3/min.
    Another airstream is coming from inside and its temperature is T2= 25 ´C, relative humidity [tex]\varphi[/tex]2= 50%, at the rate of 20 m3/min.
    The airstreams are mixed in a chamber with the pressure p = 1 bar.
    I should find the densities of the first and second mixtures (meaning the airstreams including the water). This I've accomplished, the densities being [tex]\rho[/tex]1=1.249 kg/m3 and [tex]\rho[/tex]2= 1.162 kg/m3. I've also found the mass rates for the water in both streams; [tex]^{.}[/tex]mw1= 2.0 g/s and m[tex]^{.}[/tex]w2= 3.8 g/s.

    What I havent been able to find is this: the specific humidity [tex]\omega[/tex]3 of the mixed airstreams. I simply don't know what to do: I've tried finding first the specific humidities of the airstreams before mixing and stuff like that, but I just can't get the right result! This is what it should be: [tex]\omega[/tex]3= 7.36*10-3 kg H2O/kg air.

    Can someone please help me?

    I should also find the temperature after mixing, as well as the new relative humidity, but I don't know how to do that either...
  2. jcsd
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