HCCI engine performance using fuel mixture of H2 and H2O2

Abstract

The main goal of this paper is to study a free carbon combustion engine using H2/H2O2 fuel for the HCCI engine. HCCI engine Combustion phasing, IMEP, and thermal efficiency are analyzed at different effective equivalence ratios (Phi) and engine speeds. A 3D CFD model is developed and validated with available syngas fuel combustion experimental data. This model is used to control the combustion phasing of the HCCI engine by altering the volume fraction of H2O2 in the H2/air-fueled HCCI engine. Therefore, the results show that H2O2 minimizes the inlet mixture temperature; it also helps control combustion phasing and improve combustion and thermal efficiencies at all Phi and engine speeds. Furthermore, the volume fraction of H2O2 increases the reactivity of fuel due to a high concentration of OH, which enhances the combustion rate in the crevice, resultantly high combustion efficiency. Hence, the combustion efficiency reached 97% at a 20% volume fraction of H2O2, whereas the thermal efficiency reached about 45%. On the other side, a design expert tool is used to analyze the interaction between different factors and their effect on the HCCI engine performance. It is reported that enhancement of H2O2 volume fraction and Phi has a linear effect on combustion efficiency at all engine speeds, but H2O2 volume fraction has a dominant effect. Conversely, it shows a quadratic relation between H2O2 volume fraction and Phi for thermal efficiency. It is concluded that the performance of the HCCI engine is improved with zero carbon and limited NOx emissions by using a blended fuel mixture of H2 and H2O2.