question about wet bulb temperature

[stonebrook2003]

hello, everyone
My problem is related to refrigrant substance and spray droplet evaporation. A typical question is like:
A HFA-134a liquid is preserved in pressurized container, and is injected through nozzle to room condition (1atm, 25C). Ignore the spray breakup effect. The droplets then suffer from high rate evaporation.
So my question is, suppose the evaporation time is long enough and air has zero HFA-134a, what is the eventual droplet equlibrium temperature (wet bulb temperature)?
What confuses me is, HFA-134a has its boling point around -30C at 1atm much lower than room temperature? So any way (equation?book?paper?) to calculate this wet bulb? Make necessary assumptions if you need, I guess I only need an answer under the simplest situation.

Thank you very much.

 

[quark]

What do you mean by "air has zero HFA-134a"? Under simplistic conditions, the drop in air temperature (upto the DPT) can be calculated by balancing the equation, (mxcpxdT)_134a + (mxh)_134a = (mxcpxdT)_air

Once the air reaches the dew point then, (mxcpxdT)_134a + (mxh)_134a = (mxcpxdT)_air + (moisture content x h)_air

PS: There is nothing like wet bulb in this case. If you have enough 134a and if your room has infinite thermal resistance, then lowest temperature of room can be -30⁰C

 

[Zapster]

student?

 

[stonebrook2003]

thanks for reply. I am new in this area, sorry that the question looks silly and unprofessional.
I can ask this question again with air/h2o case.
Say, a water droplet is blown by air under a typical condition (T=25C, P=1atm, V=10m/s, RH=0). And droplet will reach its equilibrium wet bulb temperature (lower than 25C for sure). But if the air is extremly hot (say 400C)? Droplet will evaporate quickly for sure, but what is its temperature (can I call it as wet bulb temperature?) during the evaporation process. Is it its boiling point (100C)? Actually, my question in general is, what is liquid droplet temperature when it is blown by air which has a temperature much higher than its boiling point at that pressure level? Seems like it is called flashing evaporation.
Thanks a lot!

 

[stonebrook2003]

PS: I think droplet temperature is its boiling point because liquid temperature remains at its boiling point when it is flashing. Does this rule apply here?

 

[quark]

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