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Thermodynamics issue with absorption heat pumps

  1. Sep 4, 2010 #1
    I have been recently trying to advance my understanding of thermodynamics, but i have encountered a problem when it comes to absorption heat pumps and similar systems.

    The standard heat pump requires an energy input, to move heat energy from one location to another. Most would consider absorption heat pumps no different as they use heat, a form of energy to operate. My consideration would say otherwise, as a standard heat pump uses, high quality energy to operate. Using high quality energy one can yield much more heat energy, using a heat pump.

    From my understanding, a Carnot heat pump creates a heat gradient efficient enough for a Carnot heat heat engine to utilise and extract the exact amount of energy that was required to create the heat gradient. There is no reduction of entropy in this perfect system and so there is no second law violation.

    If i decided to use a Carnot heat pump to operate an absorption heat pump, the heat added by the Carnot heat pump, is less than the heat expelled by the absorption heat pump. Using a Carnot heat engine to make use of the gradient, I would expect that the engine would produce surplus high quality energy, in violation of the second law.

    So where have a gone wrong in my understanding in this case?
  2. jcsd
  3. Sep 5, 2010 #2
    After more consideration I understand where my mistake has come from.

    An absorption heat pump is not purely a heat pump, it is a heat engine and a heat pump. The heat used is converted to a higher quality energy which is utilised by the heat pump.

    however I still have problems with another heat pump concept, but i will do another post for that one.
    Last edited: Sep 5, 2010
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