Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Efficiency of heat pump and refrigerator

  1. Oct 6, 2008 #1
    I know the formulas for efficiencies e of heat pump (it is e<=Tmax/(Tmax-Tmin)) and refrigerator (e<=Tmin/(Tmax-Tmin)), where Tmax and Tmin are temperatures of warmer and colder (respectively) involved containers. These formulas make me puzzled, as efficiencies seem to be possibly bigger than 1. Is that correct? If yes, what does it mean?
  2. jcsd
  3. Oct 6, 2008 #2


    User Avatar
    Science Advisor

    The http://en.wikipedia.org/wiki/Coefficient_of_performance" [Broken] of a heat engine with COP. They are not the same thing.

    Last edited by a moderator: May 3, 2017
  4. Oct 6, 2008 #3


    User Avatar

    Staff: Mentor

    In a typical heat engine, you have a certain amount of thermal energy that is converted to mechanical energy. In a heat pump or refrigeration cycle, the working fluid is being circulated to move heat between a hot and cold well. There is no direct corellation between the energy required to circulate the working fluid and the energy it is carrying with it when you move it.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook