AME 436
Assigned: 2/29/08
Problem Set #3
Due: 3/7/08 at 4:30 pm in OHE 430 for oncampus
students; DEN students submit homework through DEN
For all problems, if useful, you can use the AirCycles.xls spreadsheet to guide your answers but you need to explain your
results.
Note:
laptops or Pocket PCs running Excel spreadsheets will NOT be permitted on the exams.
Problem #1 (Cycle analysis)
For a Diesel cycle engine with the following parameters:
r = 20,
γ
= 1.3, M = 0.029 kg/mole, f = 0.05, Q
R
= 4.45 x 10
7
J/kg, initial temperature T
2
= 300K, initial pressure P
2
= 1 atm, P
exh
= 1 atm, h = 0,
η
comp
=
η
exp
= 1 (in other words, an ideal cycle), determine the following:
a)
Temperature (T
3
) and pressure (P
3
) after compression, and the compression work per kg of mixture
b)
Temperature (T
4
) and pressure (P
4
) after combustion, and the work output during combustion per
kg of mixture
c)
Cutoff ratio
d)
Temperature (T
5
) and pressure (P
5
) after expansion, and the expansion work per kg of mixture
e)
Net work per kg of mixture
f)
Thermal efficiency
g)
IMEP
You can of course check your answers with aircycles4recips.xls, but I want to see that you know the
equations behind them.
For example, for part a, P
3
= P
2
r
γ
= (1 atm)(20)
1.3
= 49.1 atm and T
3
= T
2
r
γ
1
=
(300K)(15)
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 Spring '08
 Ronney
 Thermodynamics, Combustion, Internal combustion engine, Diesel engine, ii. iii. iv.

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