代写MAE 115 APPLIED ENGINEERING THERMODYNAMICS Hw#2代写数据结构语言
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MAE 115
1. What does the area enclosed by the cycle represent on a P-v diagram? How about on a T-s diagram?
2. Someone has suggested that the air-standard Otto cycle is more accurate if the two isentropic processes are replaced with polytropic processes with a polytropic exponent n=1.3. Consider such a cycle when the compression ratio is 8, P1 = 95 kPa, T1 = 15°C, and the maximum cycle temperature is 1200°C. Determine the heat transferred to and rejected from this cycle, as well as the cycle thermal efficiency. Use constant specific heats at room temperature.
3. A six-cylinder, four-stroke, spark-ignition engine operating on the ideal Otto cycle takes in air at 14 psia and 65°F, and is limited to a maximum cycle temperature of 1600°F. Each cylinder has a bore of 3.5 in, and each piston has a stroke of 3.9 in. The minimum enclosed volume is 14% of the maximum enclosed volume. How much power will this engine produce when operated at 2500 rpm? Use constant specific heats at room temperature.
4. When we double the compression ratio of an ideal Otto cycle, what happens to the maximum gas temperature and pressure when the state of the air at the beginning of the compression and the amount of heat addition remain the same? Use constant specific heats at room temperature.
5. A four-cylinder two-stroke 2.0 L diesel engine that operates on an ideal Diesel cycle has a compression ratio of 22 and a cutoff ratio of 1.8. Air is at 70°C and 97 kPa at the beginning of the compression process. Using the cold-air standard assumption, determine how much power the engine will deliver at 2300 rpm.
6. A six-cylinder, four-stroke, 3.2 K compression-ignition engine operates on the ideal Diesel cycle with a compression ratio of 19. The air is at 95 kPa and 67°C at the beginning of the compression process and the engine speed is 1750 rpm. The engine uses light diesel fuel with a heating value of 42,500 kJ/kg, and air-fuel ratio of 28, and a combustion efficiency of 98%. Using constant specific heats at 850 K, determine (a) the maximum temperature in the cycle and the cutoff ratio (b) the network output per cycle and the thermal efficiency, (c) the mean effective pressure, (d) the net power output, and (e) the specific fuel consumption, in g/kWh defined as the ratio of the mass of the fuel consumed to the network produced.