Development of an N-Propanol Mechanism and Its Application on HCCI Engine Simulations

In this work a reduced n-propanol mechanism was obtained and implemented in the numerical simulation of the combustion process of n-propanol/air mixtures in a homogenous charge compression ignition (HCCI) engine. The first step of the research was the development of a reduced model of chemical reactions. For that purpose, twenty chemical reactions are identified, as well as their corresponding reaction constants, that when coupled to the reduced base mechanism (the San Diego mechanism) that covers up to n-butane and does not include this biofuel, can simulate combustion phenomena of n-propanol. The methodology considers extensive recent literature on detailed chemical kinetics of this biofuel and the chemical kinetics reduction is based on sensitivity analysis and steady-state approximation on the appropriate chemical species. Modeling comparison tests with experiments for flame propagation and ignition times at high temperatures for stoichiometric mixtures are reported, which supports and validates this model of chemical reactions. Then, this reduced mechanism was implemented for testing its effectiveness to simulating HCCI internal combustion engines. The results of the simulation show that the auto-ignition of the mixture depends on its inlet temperature to the combustion chamber of the HCCI engine. Thus, the use of reduced chemical models instead of detailed fuel mechanisms will allow more complex simulations of HCCI-type engines with the advantage of saving in computational time.