Development of Combustion Technology with Foam of Liquid Fuel and Air

Page 4

3 2. Mechanism of Foam Combustion Foamed liqui d fuel is made eas i 1 y by dispersing numerous air bubbles wrapped wi th very thin Ii qui d fuel film Photo 1 shows the typical example of foam J\ir bubble to be wrapped with thin liquid film which means foaming accomplish increase of interfacial area of liquid and air and dec­rease of specific heat capacity. J\s the result, evaporation rate increase markedly, and the mixture of fuel and air start burn­ing wi th small igni ter easi lYe Fig.l shows the schematic of the foam combustio~ llhe combustion steps, evaporation, diffusion, mixing with air, ignitio~ and burnin~ proceed concurrently and correspond each other. llhe simple comparison of flammability of liquid phase and foamed kerosine in the atmospheric condition are shown in Photo 2. }Cerosine does not ignite because of the lack of evaporation rate, on the other hand foamed kerosine ignites easily with just small flame torc~ Photo 1 Foam of liquid fuel F l ame Comb:Jstion Air Vapor ~ Keros; no /::: Foami ng Air ~ ~ t t j t i Foamed Keros ine ~porous Filter it Foaming Air Fig.l Mechanism of foam combustion