Thermodynamics: Internal Combustion Engine Cycles

This lecture covers the principles of thermodynamics as applied to internal combustion engines, focusing on the four-stroke cycle and the assumptions necessary for analyzing real versus thermodynamic cycles. The instructor discusses the basic concepts related to combustion engines, including the configuration parameters such as compression ratio and mean effective pressure. The lecture details the four-stroke cycle, explaining the processes of compression, combustion, expansion, and exhaust. It contrasts the ideal Otto cycle with the Diesel cycle, highlighting their respective efficiencies and operational principles. The instructor emphasizes the importance of simplifying assumptions, such as treating air as an ideal gas and considering reversible adiabatic processes. The lecture concludes with a comparison of the efficiencies of Otto and Diesel cycles, noting that while the Otto cycle generally has a higher efficiency at equal compression ratios, Diesel engines can achieve higher overall efficiencies due to their higher compression ratios. The session also includes a practical example to illustrate the thermodynamic analysis of a Diesel cycle.