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Can a hair dryer burn? Thermodynamic considerations...

  1. Feb 4, 2016 #1
    Hi all,
    I actually work in physics (quantum physics) but my thermodynamics knowledge is a bit lacking these days. The following problem has had me puzzled for quite a long time.

    Basically, if I point the hot air coming out of a hairdryer at a target, will that target's temperature ever go higher than the temperature of the hot air? I recall reading somewhere that hairdryers product air at 60 degrees C, which is just below the threshold that can cause burning.

    Thanks.
     
  2. jcsd
  3. Feb 4, 2016 #2

    BvU

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    Burning of the skin, not bursting into flames, is what they probably mean.
     
  4. Feb 4, 2016 #3

    Nidum

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    Free flowing air probably stays within temperature limits most of the time . Problem with all heat gun devices is that if exit duct is partially blocked then temperature can rise considerably . Modern equipment is usually fitted with an over temperature trip out device or full thermostatic control for safety .
     
  5. Feb 4, 2016 #4
    Thanks for the reply.
    To be clear, I'm talking about the hairdryer burning the skin, not the dryer bursting into flames. In fact I just gave the hairdryer as an example, I'm really interested in understanding the physics here: i.e. if I blow air at 60 degrees C at a wall can that wall's temperature exceed 60 degrees?
     
  6. Feb 4, 2016 #5
    If that were possible, why not just blow air at room temperature and expect things to warm up?
     
  7. Feb 4, 2016 #6
    Thanks for that answer!
     
  8. Feb 4, 2016 #7

    Nidum

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    It is possible to build machines which use a large flow of cold air to produce a small flow of hot air .
     
    Last edited: Feb 4, 2016
  9. Feb 4, 2016 #8

    A.T.

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