Development and Validation of a Model to Account for Gaseous HCl and Aluminum Surface Interactions for Spacecraft Fire Safety Applications



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49th International Conference on Environmental Systems


Experiments and modeling were performed to determine the surface kinetics of gaseous hydrogen chloride (HCl) with aluminum surfaces subjected to various treatments. HCl and other acid gases are a spacecraft fire safety concern as they are commonly found in products from electrical wire pyrolysis. Three types of aluminum surfaces were considered: surface with chromate conversion coating (iridite), anodized, and untreated. A test cell made of Teflon was used to measure the difference in HCl from the inlet to the outlet. Inlet and outlet sensors were used to measure HCl concentrations. A simple one-step global surface reaction model was proposed, and an Arrhenius surface kinetics expression that accounts for active surface sites was employed. The kinetic constants were determined (calibrated) using the measured data. The calibrated model was validated against experiments with different flow rates and HCl inlet concentrations. The results showed that anodized aluminum had the most HCl uptake, followed by the iridite and then the untreated aluminum. The amount of HCl uptake seems to correlate well with the thickness of the oxide layer on aluminum. The relevance of these findings are discussed with respect to the design of large-scale fire safety experiments in space and various fire safety application scenarios.


Justin Niehaus, National Aeronautics and Space Administration (NASA), The Ohio State University, USA
Suleyman Gokoglu, National Aeronautics and Space Administration (NASA), USA
Sandip Mazumder, The Ohio State University, USA
Gordon Berger, Universities Space Research Association (USRA), USA
John Easton, Case Western Reserve University, USA
ICES509: Fire Safety in Spacecraft and Enclosed Habitats
The 49th International Conference on Environmental Systems was held in Boston, Massachusetts, USA on 07 July 2019 through 11 July 2019.


Fire Safety, Smoke, Acid Gas, Surface Kinetics, Modeling