THANK YOU An engine has a net power output of 10.0 kW. It has a thermal efficien
ID: 1816982 • Letter: T
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An engine has a net power output of 10.0 kW. It has a thermal efficiency of 0.35 (or 35%). Heat transfer to the engine occurs by combustion of liquid fuel. Determine the net rate of heat transfer to the engine from the combusting fuel, in kW. Be sure to include the correct sign. Determine the net rate of heat transfer to/from the engine, in kW. Be sure to include the correct sign. The fuel consumption rate is 2.0 liters/hour, and the fuel costs $2.001iter. What is the cost of fuel per kW· h of work produced by the engine?Explanation / Answer
Key is the sign convention. I remember it as "to make money with a steam engine you put in heat and get out work" So "Positive flow" is heat in and work out. a. 10 KW/0.35 = +28.6 KW (heat into the engine) b. Waste heat out of engine = +10 Work - 28.6 = -18.6 (heat out) c. ( $2/ liter * 2 L/hr ) / (28.5 KW * 1 hr) = $0.14/KWH
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