Environmental sustainability, entropy generation, energy and exergy analysis of sanitary waste syngas‐diesel blends in <scp>RCCI</scp> combustion mode

Abstract This study addresses the dual challenge of waste management and sustainable energy by investigating the utilization of sanitary‐waste‐derived syngas in a dual‐fuel Reactivity‐Controlled Compression Ignition (RCCI) engine. Sanitary waste, co‐gasified with CO 2 , produces hydrogen‐rich syngas, offering a novel route for both waste valorization and partial diesel displacement. The engine was operated under varying load conditions using different diesel‐syngas injection strategies (DS2–DS10), with syngas port‐injected and diesel directly injected. A combined energy and exergy analysis was performed to evaluate combustion behavior, emission characteristics, entropy generation, and the sustainability index. The results revealed that the DS2 blend (2 ms syngas injection) delivered the most balanced performance, achieving only a 4.1% reduction in exergy efficiency compared to diesel while limiting exergy destruction and entropy generation. Higher syngas fractions such as DS10 degraded performance, leading to an 18.45% drop in exergy efficiency and a 36.26% increase in entropy generation. Compared to diesel, DS2 showed minor losses in BTE (4.68%) and exhaust energy (3.72%) but enabled a net improvement in environmental sustainability metrics. The novelty of this work lies in demonstrating the viability of sanitary‐waste syngas as a co‐fuel in RCCI mode, supported by integrated thermodynamic and sustainability assessments, extending beyond conventional biomass syngas applications by addressing the energy‐exergy trade‐offs of hydrogen‐rich waste‐derived fuels.