Hephaestus · Investigation of the ignition of a wall-impinging jet on a hot surface: fuel jet and liquid gas jet

Investigation of the ignition of a wall-impinging jet on a hot surface: fuel jet and liquid gas jet

Ignition of flammable gases, combustible liquids, or powders by hot surfaces is a critical safety concern across industries, including power generation, petroleum, automotive, chemical, and aerospace. The autoignition temperature (AIT), i.e. the minimum temperature for self-sustaining combustion without an external ignition source like a spark or flame, is regularly used to evaluate these risks. The most common methods for determining AIT are the ASTM-E659 standard [1] and the international standard ISO/IEC [2], consisting of injecting a small quantity of liquid fuel (50 to 300 µL) into a vessel heated at a constant temperature in a furnace and observing the presence or absence of a visible flame. However, numerous studies have highlighted significant limitations of the standardized tests from which AIT values are derived. It has been shown that AIT results significantly vary according to factors other than fuel characteristics, such as the material, cleanliness, shape, and volume of the vessel, the ratio of the combustible substance to air, and the ambient temperature and pressure. Moreover, the standard AIT test does not explicitly examine hot surface ignition. Instead, it involves a hot flammable atmosphere surrounded by a hot surface in a confined geometry. While this setup is valuable for evaluating hazards related to self-heating or thermal runaway, many industrial hazards involve hot surfaces in a cold atmosphere and open, unconfined conditions. Under these conditions, ignition threshold temperatures for surfaces can be much higher (500-600°C) than standard AIT values. Hephaestus project combines the expertise of two renowned research centers: the von Karman Institute for Fluid Dynamics (VKI) in Belgium under the supervision of Professor Laboureur and the Explosion Dynamics Laboratory (EDL) at the California Institute of Technology (Caltech) in the United States under the supervision of Professor Shepherd. The ambition of the project is to significantly reduce the occurrence of accidents due to accidental ignition via more robust safety assessments, contribute to better-controlled ignition processes yielding reduced pollutant emissions, and support the transition to greener energies. The aim is to provide fundamental scientific data and analyses on autoignition in a hot atmosphere and over a hot surface. The expertise acquired during the project’s first phase at Caltech has been transferred to Europe by supporting the development of a laboratory for ignition characterization of liquid gas (biogas and hydrogen). Hephaestus represents a unique chance to go beyond the state-of-the-art, achieve an in-depth understanding of the ignition processes, and update safety guidelines. [1] ASTM-E659, 2005. Standard test method for autoignition temperature of liquid chemicals. American Society for Testing and Materials. [2] ISO/IEC, 2017. ISO/IEC 80079-20-1: Explosive Atmospheres - Part 20-1: Material Characteristics for Gas and Vapor Classification-Test Methods and Data. Technical Report. International Organization for Standardization.

Data: CORDIS, © European Union