Methanol is a promising alternative fuel, which can assist in reducing emissions in heavy-duty (HD) dual-fuel (DF) compression ignition (CI) engines. In medium and large bore marine engines, DF operation is achieved through either direct injection (DI) or port fuel injection (PFI) of methanol with diesel acting as a DI pilot fuel for ignition. However, the injection of methanol presents a significant challenge due to its high latent heat of vaporization and decreased lower heating value (LHV) compared to diesel. Therefore, for the same energy content operation, methanol requires around eight times the amount of heat to evaporate completely in comparison to diesel, which results in lower in-cylinder temperatures. This charge cooling effect leads to a strong negative temperature gradient influencing ignition and flame propagation. This paper aims to quantify the cooling effect of methanol in a heavy-duty dual-fuel direct injection compression ignition (DICI) engine environment. The presented methodology uses computational fluid dynamics (CFD) simulations to model methanol sprays with validation originating from the engine combustion network (ECN) Spray D experimental data. The CFD models operate within the Lagrangian–Eulerian framework in CONVERGE-CFD using the Reynolds Averaged Navier Stokes (RANS) turbulence modeling. Compared to diesel, injecting methanol with the same energy content exhibited up to 100 K more decreased temperature within the mixture. Consequently, this cooled mixture may pose challenges to combustion stability due to the intense temperature gradients. Nonetheless, lower mixture temperature decreases NOx emissions, which can prove beneficial for high methanol energy fractions in dual-fuel DICI engines.

The advancement of DC systems, especially in transportation applications, hinges on the development of effective protection mechanisms. Robust protection systems are crucial for enabling the widespread adoption of DC technologies in important transport modes, offering both operational and economic benefits. This paper introduces a high-speed solid-state circuit breaker designed for enhancing the protection of general DC systems. The upgraded breaker integrates the functionality of a latching current limiter, designed to minimize modifications to existing technologies. A custom gate driver and controller are developed and experimentally validated to support the circuit breaker. A scaled solid-state circuit breaker prototype is tested under various operational conditions to evaluate its performance. The breaker's behavior is simulated in SPICE to guide the experimental validation on a referential DC system. The results demonstrate high performance, with a clearing time close to 200ns, effectively reducing system stress during short circuits. The current limiter functionality prevents unnecessary tripping during temporary overcurrents, keeping the current within safe parameters. The innovative gate driver simplifies the implementation of the latching current limiter, offering a practical and scalable solution. This work represents a significant step forward in DC protection technology, promoting the adoption of DC systems in transportation applications and beyond, by addressing critical protection challenges.