From predictive combustion modeling to real-time power plant digital twins: An integrated synthesis framework for low-carbon marine engines

The transition toward low- and zero-carbon marine power systems requires engine development methods that can evaluate alternative fuels, advanced combustion modes, thermal constraints, control strategies, and system-level interactions before extensive experimental implementation. This paper synthesizes the main modeling developments established within the Computationally Aided Systems Engineering for Marine Advanced Technology for The Environment (CASEMATE) framework for simulation-driven development of next-generation marine engines. The framework is organized as a traceable model hierarchy linking fuel-flexible chemical mechanisms, UVATZ-based multi-zone combustion simulation, spray and stratification modeling, combustion–thermal coupling, one-dimensional engine simulation, fast-running model reduction, functional mock-up unit modularization, and model-based systems engineering workflows. At the combustion level, the framework consolidates predictive submodels for multi-fuel Reactivity controlled compression ignition (RCCI) operation, with engine-level validation concentrated mainly on diesel–natural-gas and hydrogen-enriched RCCI cases, while ammonia-related pathways are treated at the chemical-kinetic validation level. At the engine level, these models are coupled with multi-cylinder and air-path simulations to support performance and emissions optimization under realistic boundary conditions. At the system level, reduced-order and real-time-capable representations enable hardware-in-the-loop deployment and hybrid power plant digital twin applications. Representative case studies demonstrate the use of the framework for analyzing thermal-emissions trade-offs in RCCI combustion, hydrogen-enriched combustion control, retrofit potential of existing diesel platforms, and MBSE-compatible power plant simulation. The synthesis shows that the integrated framework provides a pathway from fundamental combustion modeling to real-time system-level validation, reducing reliance on sequential experimental iteration while preserving the physical interpretability required for engineering decision-making. The framework should be interpreted as a synthesis of implemented and partially coupled model components rather than as a single fully automated end-to-end software package. Remaining challenges include generalization beyond RCCI-dominated combustion modes, broader marine-engine validation of hydrogen-rich and ammonia-containing operation, improved treatment of NH 3 slip, N 2 O, NOx, spray-wall interaction, and transient effects, and further automation of requirement-driven model configuration for industrial deployment.