A thermodynamic cycle in which only air is admitted in the intake stroke. The air is then adiabatically compressed, and fuel is injected into to the hot air in the form of many small drops (not a vapor). Each drop burns over a small time, giving an approximation of a isobaric explosion. This is one of the reasons that no shock wave is formed even though the air temperature and pressure are high when the fuel is injected. The explosion pushes the cylinder outwards. The power stroke, valve exhaust, and exhaust stroke which follow are identical to those in the Otto cycle.
The maximum theoretical efficiency of a Diesel engine is
where is the heat capacity ratio.
are the expansion and compression ratios and
References
Zemansky, M. W. Heat and Thermodynamics: An Intermediate Textbook, 5th ed. New York: McGraw-Hill, pp. 174 and 176-177, 1968.
