Simple thermal efficiency check 1

[jmoth79]

The working fluid of a power plant executes a thermodynamic cycle with thermal efficiency of 40%. The working fluid is heated by the hot gases in a coal-fired furnace, and cooled by water from a river. How much heat transfer from the hot gases occurs, for each joule of heat transfer to the river water?

So, I just used the thermal efficiency equation: n = 1 - Q out / Q in. Plugging in 0.4 for n , and 1 Joule for Q out.
I calculated 0.714 Joules for an answer. Is this correct?

 

[Dougt115]

No. Your method is ok but your math is bad 1-1/.714 = -.4. Answer should be 1.67

Qin > Qout Unless you are measuring the water at the inlet and outlet?

How and where you measure Qin and Qout would be interesting.

 

[jmoth79]

Yes, silly math mistake. Thanks for correcting!