Carnot engine air conditioner

1. Apr 30, 2010

noname1

A Carnot air conditioner takes energy from the thermal energy of a room at 76°F and transfers it as heat to the outdoors, which is at 96°F. For each joule of electric energy required to operate the air conditioner, how many joules are removed from the room?

Attempt at problem

76 + 273 = 349
96 + 273 = 369

COP = energy removed / elec energy required

COP = 349 / (369 - 349) = 17.45

17.45 = energy removed / 1 Joule

the system is always saying that my answer is incorrect but i cant figure out what

2. Apr 30, 2010

vela

Staff Emeritus
Your temperatures are in Fahrenheit, not Celsius, so you're converting them to absolute temperatures incorrectly. The rest looks okay, though.

3. Apr 30, 2010

noname1

shoot i didnt notice that but anyways converted now but the system still says i got the wrong answer

(5/9)(76-32) = 297.44
(5/9)(96-32) = 308.56

COP = energy removed / elec energy required

COP = 308.56 / (308.56 - 297.44) = 27.75

27.75 = energy removed / 1 Joule

i cant find out whats wrong

4. Apr 30, 2010

vela

Staff Emeritus
You're using the wrong temperature in the numerator.