Thermo-physical properties of marine lubricant/hydraulic fluids and enhancing hot surface ignition characteristics considering coupling influences

Abstract

Ship fires frequently originate from an accidental ignition of spilling marine fuels on hot surface in engine room, yet detailed characterization of the initial ignition behavior remains limited. This study investigates the hot surface ignition (HSI) characteristics of marine lubricant and hydraulic oil under simulated ship engine room conditions using a dedicated experimental platform. Critical ignition parameters and thermal data were systematically obtained. The results reveal that the vapor-air mixture formed after fuel contact with the hot surface exhibits a highly stratified distribution in the vertical dimension, distinct from conventional marine diesel. As the hot surface temperature T_s increases, the initial HSI position shifts closer to the high-temperature substrate. Following flame kernel formation, the flame propagates downward toward the hot surface, with hydraulic oil exhibiting higher heat flux intensity compared to the marine lubricant. When hot surface temperature T_s exceeds 765 K, the HSI delay time of the marine lubricant stabilizes, whereas the hydraulic oil continues to show significant variability. Based on heat transfer theory and experimental data, an ignition delay prediction model is developed, and a probability-based HSI assessment framework is specifically optimized for these fuels. By integrating multi-parameter measurements and validation data, this study provides a novel methodology for evaluating the initial fire risks associated with specialized marine fuels in ship engine room.