Effect of water fogs on the deliberate ignition of hydrogen. Final report

This report presents an experimental evaluation of the effects of water fog density, droplet diameter, and temperature on the lower flammable limit (LFL) of hydrogen-air-steam mixtures. The results show that the LFL for hydrogen in air at 200C is only marginally higher with fog than without. Most of the nozzles tested at 200C raised the hydrogen LFL from 4.0 vol % to about 4.8%, for the case of dense fogs with volume-average drop size in the range 45 to 90 microns. The lower flammable limit at 500C was typically 7.2% for dense fogs with drop size in the range 25 to 50 microns. The lower flammable limit at 700C was typically 7.6%. Typical fog concentrations ranged from 0.03 to 0.09 vol % at 200C and decreased with increasing fog temperature. 7 figures, 4 tables