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
Two air-standard Otto cycles are to be compared. Both use air treated as an ideal gas with constant γ=Cp/CV=1.40, both are run quasistatically as closed cycles with no friction and no heat leaks, both begin the compression at T1=290K, and in both the constant-volume heat input brings the gas to the same peak temperature T3=2100K. One has compression ratio r=6, the other r=20.
((a)) Find the efficiency of each cycle.
((b)) Find the Carnot bound between the extreme temperatures of these cycles.
((c)) For each cycle, find the fraction of that bound it achieves, and say in one sentence why neither cycle reaches it.