Ok, my question is as follows:(adsbygoogle = window.adsbygoogle || []).push({});

An inventor claims to have developed an engine that takes in 10^8 J (Q_in) at a temperature of 400 K (T_2), and rejects 4x10^7 J (Q_out) to a reservoir of Temperatue of 200 K (T_1). The engine delivers 15 kilowatt hours of mechanical work (which = 3600 sec/hour *15 * 10^3 watts = 5.4x10^6 Joules). Would you advise investing money to put this engine on the market?

the way i approached it was to calculate the max efficiency that a carnot engine would have, which is:

efficiency = 1 - T_1/T_2 = 1 - 200/400 = 0.5 or 50%

Now, using the expression,

Efficiency = Work output/Heat inputfor the hypothetical engine gives. This gave me an efficiency of roughly 54%, and by Carnot's theorem, no engine can be more efficient than a carnot engine, or:

Efficiency(carnot) > Efficiency(hypothetical)and in this case, it doesnt hold, i.e.:

50 % > 54 % is not true.

Is this the correct way to do this problem?

Thanks

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# Homework Help: Thermodynamics engine question

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