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Heat engine

  • Thread starter flower76
  • Start date
  • #1
51
0
I'm not sure if I'm interpreting this question correctly

A heat engine operated between 40C and 380C. Being a real engine, it efficiency is only 60% of that theoretically possible for a Carnot engine at these temperatures. If it absorbs heat at a rate of 60kW at what rate does it exhaust heat?

So should I be finding the ideal (Carnot engine) and then taking 60% of that?

ideal = 1-Tl/Th = 1- (313K/653K) = 0.52

so then I figured it runs at 60% of ideal so e should be 0.312

Is this right or is e just 60% ??
 

Answers and Replies

  • #2
2,985
13
You are almost there. You did not answer what the question asked of you, it said what rate does it exhaust heat, not the efficiency.
 
  • #3
51
0
If e is 0.312

then 0.312 = (Qh-Ql)/Qh
0.312 = (60 kJ/s - Ql)/60 kj/s

Ql = 41.3 kj/s So it exhausts at a rate of 41.3 kj/s

Does this look right?
 
  • #4
2,985
13
seems reasonable.
 

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