The Effects of iso-propanol and n-heptane Fuel Blends on HCCI Combustion Characteristics and Engine Performance

Abstract

In this study, the effects of iso-propanol fuel blends were investigated on HCCI combustion and engine performance. The variations of cylinder pressure, heat release rate, start of combustion and engine performance were studied in a single cylinder, four stroke, gasoline HCCI engine. The experiments were conducted at different inlet air temperatures at constant air excessive coefficient (λ=2) and engine speed (1500 rpm). The test results showed that cylinder pressure and heat release rate delayed with the addition of iso-propanol in the test fuels. It was also found that the increase of inlet air temperature causes to advance the combustion. Iso-propanol has higher octane number compared to conventional fuels. However, calorific value of iso-propanol is lower than conventional fuels. The aim of this study is to research the usage of iso-propanol in HCCI engines. The experimental findings showed that the tendency of knocking combustion decreased with the increase of the amount of iso-propanol. The start of combustion was delayed with the increase of the amount of iso-propanol. In addition, combustion duration decreased with the addition of iso-propanol in HCCI combustion. As a result, knocking can be prevented using iso-propanol in HCCI engines. This effect also led to extend the HCCI operating range