Mechanical Engineering homework help. ME 325: Thermodynamics 2
Homework assignment 6
Note: For problems 1-3 it may be helpful to implement your solution in a spreadsheet program.
At the beginning of the compression process of a cold-air standard Otto cycle, p1 = 1 bar, T1=290K, V1=400cm3. The maximum temperature in the cycle is 2200K, and the compression ratio is 9.
- The mass of each charge of gas.
- The heat addition in kJ
- The net work in kJ
- The thermal efficiency
- The mean effective pressure in bar
- The temperature of the gas being exhausted (take as state 4), Why would this matter?
- The work required/extracted to exhaust the charge
- The work required/extracted to intake a fresh charge
Of the above problem statement, which values change If the compression ratio is instead 8? What are the new values?
What would happen if instead of a fixed maximum temperature, the same amount of heat addition from Problem 1 was added to an engine with a compression ratio of 8? Which values change and how?
The pressure and temperature at the beginning of compression of a cold-air-standard diesel cycle are 120kPa and 300 K respectively. At the end of the heat addition, the pressure is 80 bar and the temperature is 2150K.
- The compresison ratio
- The cutoff ratio
- The thermal efficiency of the cycle
- The mean effecive pressure in bar