文档介绍：Thermal Energy Problem Set #6– Fall 2002
Time spent on problems:
Problem 1:
Problem 2:
Problem 3:
Problem 4:
Problem 5:
Problem 6:
Thermal Energy Problem Set #6 – Fall 2002
Do all problems. Please use a separate sheet of paper for each problem.
1. An Otto cycle with pression ratio of operates from the suction conditions of
100 kPa, 30oC. Find the pressure and temperature at the end of pression (a)
if cold air (k=) is the working substance, (b) if hot air (k=) is the working
substance. Compare answers. (c) Solve for the ideal thermal efficiency based upon
the conditions given in (a) and (b).
2. For an ideal Otto engine operating with cp=1 kJ/kgK, the temperature at the end of
pression is 450oC and at the end of expansion is 1400oC. The
compression ratio is r=. Find the work and the efficiency.
3
3. An ideal Diesel engine operates on m (measured at state 1) of air. Let P1=100
o
kPa, T1=60 C, r=14, and let the cutoff be at 6% of the stroke (where cutoff is V3-V2).
Draw the P-V and T-s diagrams, use cp=1 kJ/kgK, and find (a) T2, P2, V2, T3, V3, P4
and T4; (b) Qin and Qout; (c) W and η.
4. Reynolds and Perkins, Engineering Thermodynamics, 2nd Ed. Problem ,
5. Reynolds and Perkins, Problem , pp. 372
6. Scramjets or ramjets are