Extending the operating range of HCCI engines with the rhombic drive mechanism: A novel concept
FUEL, cilt.430, 2027 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 430
- Basım Tarihi: 2027
- Doi Numarası: 10.1016/j.fuel.2026.141611
- Dergi Adı: FUEL
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Chimica, Compendex, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Gazi Üniversitesi Adresli: Evet
Özet
Homogeneous charge compression ignition (HCCI) engines offer high thermal efficiency and very low nitrogen oxides (NOx) and soot emissions, but they have significant challenges such as a limited operating range, knocking at high loads, and misfiring at low loads. In this study, the use of a rhombic drive mechanism as an alternative to the conventional crankshaft mechanism was numerically investigated for the first time to extend the operating range of HCCI engines. A total of 301 computational fluid dynamics (CFD) simulations were performed using CONVERGE CFD, employing an HCCI engine model validated with experimental data. The simulations were conducted at engine speeds of 800-2600 rpm, within a lambda range of 1.3-3.4, using fuels with research octane numbers of 20 and 40 (RON20 and RON40). The results showed that the rhombic drive mechanism extended the compression phase, allowing the piston to remain near top dead center (TDC) for a longer duration. This increased the average cylinder temperature, facilitating auto-ignition and enabling stable HCCI combustion near the low-load limit at higher engine speeds. With the rhombic drive mechanism, heat release was more concentrated around TDC, the combustion duration was shortened, and the combustion process approached a constant-volume character. The principal contribution of the rhombic drive mechanism was extending the upper engine-speed limit of naturally aspirated HCCI operation. The low-load improvement was secondary, while higher MPRR under identical engine-speed and lambda conditions showed no direct extension of the high-load limit at a fixed speed.