Abstract
• Novel eight-process hybrid engine cycle is introduced. • Includes Carnot, Miller, and Takemura cycle features. • Analyzed using Finite-Time Thermodynamics (FTT). • Optimum operating conditions are determined. The Carnot cycle is widely recognized in the literature as the most efficient cycle due to its heat transfer occurring at constant temperature processes. Consequently, practical engine cycles should ideally approach the Carnot cycle to maximize thermal efficiency. In recent years, the Miller cycle has emerged as an environmentally friendly alternative, extensively applied to reduce NOx emissions from internal combustion engines (ICEs). By lowering the compression ratio and increasing the expansion ratio, the Miller cycle effectively reduces maximum in-cylinder combustion temperatures, thereby significantly slowing down NOx formation. The Takemura cycle is another method that hasn’t been studied as much. It adds heat to the engine cylinder while keeping the combustion temperatures almost constant. This study presents a novel eight-process cycle that integrates the Carnot, Miller, and Takemura cycles, developed through advanced numerical models and computational techniques. The goal of this novel cycle is to reduce emissions and increase engine efficiency beyond what can be achieved with individual conventional cycles. Key performance metrics, including effective power (EFP), effective power density (EFPD), exergy destruction (X), exergy efficiency (ε), ecological coefficient of performance (ECOP), effective ecological power density (EFECPOD), effective ecological performance coefficient (EFECPEC), and effective exergetic performance coefficient (EFEXPEC), have all been taken into consideration in a thorough performance analysis of the suggested cycle engine. A thorough investigation has been conducted into the effects of engine design and operating parameters on these performance metrics. Furthermore, irreversibilities associated with incomplete combustion loss, exhaust output loss, heat transfer loss, and friction loss have been incorporated into the performance simulations.