HCCI engine performance using fuel mixture of H₂ and H₂O₂

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.