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.
Problem 1)
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.
Determine)

1. The mass of each charge of gas.
2. The heat addition in kJ
3. The net work in kJ
4. The thermal efficiency
5. The mean effective pressure in bar
6. The temperature of the gas being exhausted (take as state 4), Why would this matter?
7. The work required/extracted to exhaust the charge
8. The work required/extracted to intake a fresh charge

 
Problem 2)
Of the above problem statement, which values change If the compression ratio is instead 8? What are the new values?
 
Problem 3)
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?
 
Problem 4)
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.
Determine)

1. The compresison ratio
2. The cutoff ratio
3. The thermal efficiency of the cycle
4. The mean effecive pressure in bar

Mechanical Engineering homework help