A small petrol generator engine is modelled by an air-standard Otto cycle: a fixed…
PHYSICS · Multi-part · Fermi University Physics · Thermal, Statistical & Complex Systems · The laws of thermodynamics · The laws of thermodynamics
Thermal Physics, Ch Internal-combustion cycles and indicator diagrams
Problem
A small petrol generator engine is modelled by an air-standard Otto cycle: a fixed mass of air treated as an ideal gas with constant γ=1.40, all four legs quasistatic, heat added and rejected at constant volume, friction and heat leaks removed. The compression ratio is r=V1/V2=7.0, the compression starts at T1=295K, and the constant-volume heat input takes the gas to a peak of T3=1750K.
((a)) Find the temperature T2 at the end of the compression.
((b)) Find the temperature T4 at the end of the expansion.
((c)) Find the efficiency of the cycle, once from the four temperatures and once from r alone, and check that the two agree.