1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Heat engine

  1. May 24, 2008 #1
    1. The problem statement, all variables and given/known data

    A machine with COP = 5.0 removes 25kJ of heat from a cold reservoar. If the machine is reversible and driven the other way as a heat engine, what is the efficiency?

    3. The attempt at a solution

    COP = QL/W --> W = 5kJ

    e = QH/W

    Is QH the same as QL som that e = 20%
     
  2. jcsd
  3. May 25, 2008 #2

    alphysicist

    User Avatar
    Homework Helper

    Hi kasse,

    No, I don't believe that [itex]Q_H[/itex] and [itex]Q_L[/itex] are the same. Using conservation of energy, you can find out how Qh, QL, and W are related. What do you get?

    Also, your efficiency formula needs to be:

    [tex]
    e=\frac{W}{Q_H}
    [/tex]
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook




Loading...
Similar Threads for Heat engine Date
Radiative heat engine Mar 29, 2018
Simple 3 stage engine Jul 27, 2017
Calculating the Efficiency of a Heat engine Apr 17, 2017
Temperature in a Carnot heat engine Apr 16, 2017