(44b) Minimum Ignition Energy Study of Flowing Heat Transfer Fluid Aerosols: Experimental and Theorectical Approach

Liquid-gas aerosol has been a significant concern in process industries for its complexity and unpredictability of formation, ignition probability, combustion mechanisms, and flame propagation with impact on onshore/offshore facilities. Heat transfer fluid, specifically, has been proved to have the possibility to form aerosol from pressurized leaking, spraying, and potential liquid impingment from surfaces. Having more combustible matter and higher energy density, the high-flash point aerosol may induce more hazardous fires and explosions even operated or stored under the safety limits. Among the indicators describing flammability, minimum ignition energy (MIE) is one of the most widely used and studied ones. It is capable to reflect the internal chemical properties of the material, as well as to make connection to analyze the possible facility ignition sources. This paper demonstrates MIE experimental result of commercial heat transfer fluid aerosols, and develops COMSOL-Multiphysics models as theoretical approach on MIE prediction of similar chemical species. The influence of aerosol droplet sizes, initial spray velocity, fuel-air equivalence ratio, and fluid temperature are analyzed. The characteristic ignition temperature, which is the "flash point" of aerosol system, is also developed to compare with single-phase material. Results of the study may be used for industry liquid handling, working fluid selection, mitigation design, and ignition elimination to prevent fire and explosion of aerosols.