A diesel engine has a compression ratio of 22: 1. the conditions in the cylinder

Question

A diesel engine has a compression ratio of 22: 1. the conditions in the cylinder at the start of compression are p = 101. 3 kPa and T = 325 K. Calculate the pressure and temperature at the end of compression, assuming the compression process is isentropic: Assume the cylinder contains an ideal gas with gamma = 1. 4 and R= 287 J/kg K. Assume the cylinder contains air which may be regarded as a semiperfect gas (use the gas tables). Compare the work of compression in (a) and (b) above. In practice, heat losses reduce the final compression temperature by 100 K. For a diesel engine operating at an equivalence ratio of 0. 75 (full load): Calculate the ratio of heat loss during compression to the fuel energy added per cycle.

Explanation / Answer

P1 = 101.3 KPa T1 - 325 K a) P2 = 22*P1 = 2228.6 KPa T2 = T1*(P2/P1)^(y-1/y) = 786.018 K where y = 1.4 b) P2 = 2228.6 KPa T2 = use gas table (sorry, i don't have) c) work for compression would be more foe semiperfect gas. Idael gas requires the least work input d) heat loss = Cp*(100) = 100.5 KJ fuel energy added per cycle = 0.75*43400/4 KJ Ratio = 0.012

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