Experimental study on hot surface ignition and flame characteristic parameters of lubricating oil

Lubricating oil (LO) is an extensively applied fuel in industrial processes, often operating under high temperature and high-pressure conditions, which makes it prone to hot surface ignition. Hot surface ignition of LO is one of the potential sources of fire incidents in industrial processes and automotive lubrication systems. Taking LO as the object, a hot surface ignition experiment was conducted, using a self-developed test rig, image processing technology, and statistical analysis methods. The lowest ignition temperature of 311 degrees C was found. When the hot surface temperature exceeded 407 degrees C, the probability of ignition was prominent. Utilizing experimental probability data, a predictive model for ignition probability was established. In addition, the study discusses three stages of combustion and free radical generation, as well as the ignition delay time, flame duration, and flame height. Finally, the experimental results are compared with the measured distance of the automobile pipeline to quantify the fire risk of leaked LO. It is indicated that the dependence of ignition delay time on temperature is more substantial than oil volumes. As the volume of LO increased, the minor ignition temperature became smaller, and the probability of ignition decreased. The time when the flame height reached the measured distance accounted for 65-79% of the flame duration, and the average flame temperature was 1162-1347 degrees C. These results can quantify the danger of hot surface ignition resulting from leaked LO and guide the safety design for the automobiles.