Design and Characterization of a Hot-Surface Ignition (HSI) Experiment

The ignition of flammable liquids on hot surfaces is both a safety concern to industry and an important phenomenon for some combustion devices. Hot-surface ignition (HSI) is a function of fluid properties and environmental parameters, primarily surface temperature. In the current study, a laboratory-scale experiment was designed and characterized to determine the HSI characteristics of flammable liquids. A stainless-steel block is heated using embedded electrical resistance heaters and single drops of liquid fuel are dispensed onto removable test surfaces. The experimental apparatus is well-characterized and provides a uniform surface temperature within the range of 25-750 °C with high accuracy (±5 °C) and control. Experimental measurements include temperature-dependent ignition probability and time-to-ignition. In addition, high-speed video was utilized to further probe the underlying phenomena that govern HSI behavior. Representative HSI data for heptane, nitromethane, and lubricant oils are presented to illustrate the utility of the developed experiment in providing valuable HSI data and elucidating the fundamental parameters that influence HSI behavior.