Conductive heat transfer through basement wall

[omc1]

Homework Statement

In an electrically heated home, the temperature of the ground in contact with a concrete basement wall is 13.8oC. The temperature at the inside surface of the wall is 20.8oC. The wall is 0.118m thick and has an area of 9.43m2. Assume one kilowatt*hour of electrical energy costs $0.10. How many hours are required for one dollar's worth of energy to be conducted through the wall?

Homework Equations

q=KAdeltaT/L

The Attempt at a Solution

(1.7)*(9.43)*(20.8-13.8)/0.118=950.99 W $1=10000Whr
10000/950.99=1052 hrs...not working though?

 

[mpreds]

Where did you find your k value? And is it in the correct units?

-Mark

PS: You did mean to write 10.52 hrs I hope?

 

[omc1]

yes i mean to write that, I got 1.7 from online source, but someone else also used 1.5 but neither of those works?

 

[mpreds]

Are you working from a textbook? Check to see if there is any data tables in the back that may contain concrete.

http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

Shows a range of 0.1 - 1.7 for concrete k values