The performance of a given Diesel engine is approximated by the limited-pressure cycle. The compression ratio of the engine is
15:1
and the total heat added to the cycle is
1935 kJ
per kg of working fluid. The conditions prior to compression are as follows:
P=100kPa
and
T=290 K
. Assume that
γ=1.3
and
R=0.287 kJ/kg−K
. Note: Here
γ=1.3
means that the mixture properties are slightly different than pure air, but the compression is still isentropic. a) Assuming that half of the total heat is added at constant volume and half at constant pressure compute the indicated thermal efficiency of the limited pressure cycle. b) Compare the efficiency and peak pressure of the limited-pressure cycle with the efficiency and peak pressure that would be obtained if the same total heat were added at constant volume or at constant pressure. Tabulate your results and explain whether the calculated values meet expected trends and why?