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Thread: About fans, air and temperatures.

  1. #1
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    About fans, air and temperatures.

    It's summer, it's warm, I'm using a fan.

    Is the air coming from a working fan cooler than the surrounding air, or is it exactly the same temperature?

    We all know a fan helps when it's warm, but, we also know that it only speeds up the surrounding [warm] air, right? ...or is it right?

    I have NO idea what I'm talking about, but I think that sped up air somewhat cools down, so that it's cooler than static air.

    Again, I have no clue as to what I'm saying or thinking, so maybe we can clear this age old question up once and for all.
    Besides, it gives us something to do on this warm Saturday.
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  2. #2
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    Re: About fans, air and temperatures.

    Air from a working fan will be the same temp as the surrounding air. (OK, technically its is probably hotter, as fans tend to be aircooled...but what difference is 0.01C going to make?)

    the only reason why fnas feel cool is because they increase the rate which air conacts your body. Sweat is evaporative cooling, and the more air conact the better the cooling effect.
    Last edited by cascade9; June 26th, 2010 at 05:20 PM. Reason: typos

  3. #3
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    Re: About fans, air and temperatures.

    Quote Originally Posted by Phrea View Post
    It's summer, it's warm, I'm using a fan.

    Is the air coming from a working fan cooler than the surrounding air, or is it exactly the same temperature?

    We all know a fan helps when it's warm, but, we also know that it only speeds up the surrounding [warm] air, right? ...or is it right?

    I have NO idea what I'm talking about, but I think that sped up air somewhat cools down, so that it's cooler than static air.

    Again, I have no clue as to what I'm saying or thinking, so maybe we can clear this age old question up once and for all.
    Besides, it gives us something to do on this warm Saturday.
    Here in the forum need more fanboy.... mmmhh...
    I rephrase it
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    .


    We need more fangirl
    What if someday login in your facebook account you're required to accept yet-another-update license agreement saying you're a total idiot? Quit Facebook, join Diaspora*
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  4. #4
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    Re: About fans, air and temperatures.

    Technically, the fan moving the air will cause air friction, which will generate heat, but that should be very minuscule compared the increase in evaporative cooling.

  5. #5
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    Re: About fans, air and temperatures.

    All that the fan will do is accelerate evaporation of sweat or other moisture on your skin. Ever notice how fans seem to work really well when you just step out of the shower or back inside after getting sweaty?

    When water evaporates, the hottest water molecules evaporate first, leaving the coolest molecules to cool you down.

  6. #6
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    Re: About fans, air and temperatures.

    Quote Originally Posted by Austin25 View Post
    Technically, the fan moving the air will cause air friction, which will generate heat, but that should be very minuscule compared the increase in evaporative cooling.
    The motor driving the fan will generate a measurable amount of heat though.

  7. #7
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    Re: About fans, air and temperatures.

    the air temperature will be the same, or slightly rising as the fan motor generates additional heat.

    The cooling effect is
    A/ wind chill : if your body temp is higher than the ambient temperature, your body heats up the air around you. a continous flow of air then will transport heat away from you, allowing more heat to be transferred from your body to the surrounding air.

    B/ evaporation : moving air facilitates evaporation (possibly because it has lower pressure of itself, or because the airflow around your body causes the air pressure to decrease, the way it does around airplane wings)
    evaporation requires energy, so as fluids on your skin (sweat, or water after a shower, or ...) make the transition from liquid to vapor, they use heat from your body. And you cool off.

  8. #8
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    Re: About fans, air and temperatures.

    Take that same fan, place a tub or large deep flat pan with water and a folded towel. Blow the air across that and you have a cheap evaporative cooler. Of course if you live along the Gulf coast or in any high humidity area .. it won't work .. if you live in Yuma, it will work.

    I'll use an air conditioner, thank you!! Even casement types are better than fans!!

  9. #9
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    Re: About fans, air and temperatures.

    Quote Originally Posted by Phrea View Post
    It's summer, it's warm, I'm using a fan.

    Is the air coming from a working fan cooler than the surrounding air, or is it exactly the same temperature?

    We all know a fan helps when it's warm, but, we also know that it only speeds up the surrounding [warm] air, right? ...or is it right?

    I have NO idea what I'm talking about, but I think that sped up air somewhat cools down, so that it's cooler than static air.

    Again, I have no clue as to what I'm saying or thinking, so maybe we can clear this age old question up once and for all.
    Besides, it gives us something to do on this warm Saturday.
    Let me give you my answer in the same style as your question:


    The air coming from a working fan is cooler than the surrounding air, at least it feels cooler anyway.

    It is a know fact that fans do help keep us cool, it is also a know fact that the cause of this is that the air-speed increase heightens the relative density of the air, making us feel cooler ...at least that's my view on things anyway.

    To be honest, I'm not totally sure what I'm talking about, but perhaps it's got something to do with fast-moving air causing static electricity - or something.

    In conclusion, I don't have a clue why I'm writing this, or indeed, what the original question was. Perhaps someone else can provide a coherent response? Besides, I'm sure, in acquiring the answer, said person can reach a new level of intellectual enlightenment (even though I'm not exactly sure what that means). Good luck.
    Last edited by Penguin Guy; June 26th, 2010 at 08:20 PM.

  10. #10
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    Re: About fans, air and temperatures.

    I think fans probably work the same way as wind chill.

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