# Engine Optimization Model for Accurate Prediction of Friction Model in Marine Dual-Fuel Engine
###### Abstract
Additionally, fine-tuning valve timing can decrease pumping losses, which indirectly reduces engine friction [16; 17; 18]. Experimental testing is essential for estimating and validating friction forces within engines [19; 20], while few experimental studies have been performed. Techniques such as fired engine tests or pressurized motoring tests are commonly used to measure friction. Research has also assessed the lubrication conditions between the piston ring and cylinder liner in different diesel engines, with numerical models validated through experimental data to show how surface roughness affects engine performance [21; 22]. In low-speed diesel engines, friction measurements on components such as the piston assembly-cylinder liner, piston rod stuffing box, and crosshead slipper-guide have been conducted to improve tribological performance and reduce fuel consumption [23]. This has led to the exploration of biodiesel blends in lubricating oils, which often exhibit superior lubrication properties compared to conventional diesel [24; 25]. For instance,a 10% biodiesel-oil blend can reduce both the friction coefficient and wear scar diameter [26; 27; 28; 29]. The addition of nano-lubricants has shown further potential for enhancing the lubrication properties of diesel engines [30; 31; 32]. Furthermore, selecting optimal cylinder bore coating materials is vital to minimizing fuel consumption and exhaust emissions while ensuring engine reliability [33; 34]. Numerical simulation is pivotal in the development of new engine technologies, enhancing production efficiency and ensuring precision, especially with the increasing complexity of controlling engine subsystems via the engine control unit (ECU). [PERSON] et al. [35] emphasized that the 0D/1D models used in this study allow comprehensive control over various engine components while offering faster computational times compared to 3D computational fluid dynamics (CFD) models. While 3D CFD models offer detailed insights into specific phenomena, they are computationally intensive, making 0D/1D models ideal for early-stage development and system-level analysis. Engine models also serve as valuable tools for simulating performance with different fuels. For example, [PERSON] et al. [36] used AVL's BOOST software [37] to study the impact of Early Intake Valve Closure (EIVC) on engine performance. Their findings revealed that EIVC significantly increases the heat release rate, resulting in higher nitric oxide (NO) emissions and potential misfires under low-load conditions. [PERSON] et al. [38] utilized WAVE 2019.1 from Ricardo Wave Software [39] to simulate the behavior of a marine diesel engine, validating the model with experimental data. The model accurately predicted emissions during sea trials, demonstrating its reliability in evaluating engine performance and environmental impact. Similarly, [PERSON] et al. [40] used GT-Power [41] to explore how turbocharger performance degradation affects overall engine performance in both diesel and gas modes. Their results showed a downward trend in key parameters like the turbocharger speed, boost pressure, peak pressure, and brake thermal efficiency, while the exhaust temperature and emissions increased, highlighting the critical role of turbocharger health in engine efficiency. [PERSON] et al. [42] and [PERSON] et al. [43] investigated the transition of marine engine performance across various operating points using a 1D engine model. This model is developed as a digital twin to reflect real-time engine operation onboard ships, enabling better control and optimization of marine engines under varying conditions. Thanks to the use of Application Programming Interfaces (APIs), engine models can be seamlessly integrated with third-party software to perform optimization procedures. For instance, [PERSON] et al. [16] coupled WAVE with a nonlinear optimizer to identify the key parameters of the turbocharger, valve, and injection system of a large marine diesel engine, optimizing performance across the engine's operating range.