Question

Problem #2 17.5 pts)Topic. Entropy A typical gasoline engine operates at 200°F while the maximum temperature inside the combustion chamber can be 1100F. On the other hand, the temperature of the combustion chamber of a typical diesel engine can reach up to 2500 F. So let's compare the performances of two Carnot cycles, one operating between ~1100°F and 200°F heat reservoirs and the other between ~2500°F and 200°F, to have a first-order crude estimate of engine performance Step a) Choose a temperature between 1050 F and 1150 F. Your temperature should have two digits below decimal point (e.g., 982.14°F is fine but 982 F is not). Use it as the hot temperature for your Carnot cycle A. Choose a temperature between 2450°F and 2550°F. Your temperature should have, again, two digits below decimal point. Use it as the hot temperature for your Carnot cycle B. Both cycles have 200 F for the cold temperature. For both cycles, compute: Efficiency, work delivered per pound of working fluid, entropy (per pound of working fluid) that is being dumped to the cold side Step b) Suppose you built a physical prototype of cycle B. You measured the efficiency of the cycle and found that the work output per pound was 5 per cent lower than what you obtained in step a. Compute the efficiency of the cycle, and entropy (per pound) that is being dumped to the cold side.

Answer 1

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