CONCLUSIONS 



The work conducted to date indicates that radiant heat transfer can account for 

 only 40 percent of the total heat flux necessary to sustain a spreading fire. 

 Convective heat transfer at the interface of the combustion zone and the new fuel 

 probably accounts for the rest. Burning characteristics and flame depth are strongly 

 controlled by the fuel particle size and the porosity of the bed. In porous beds the 

 residence time of a fire is controlled by the particle size. A direct relationship 

 seems to exist between residence time and particle size. 



Fuel beds of solid fuel elements can be correlated to liquid pool fires by using 

 the ratio of fuel bed density to cold vapor gas density. Three burning regimes, 

 turbulent, transitional, and laminar, exist in solid fuels and may contribute to 

 discrepancies found among various sets of experimental fires. 



A group of selected fuel descriptors consolidates the more important parameters 

 into a measure of the bulk heat requirement, B.t.u./ft.^, and, with the experimental 

 rates of spread, indicates the maximum heat flux is near 40 X 10^ B.t.u./ft.2 - hr. 

 (3 cal . /cm. 2 - sec . ) , 



The tallest flames and highest burning rates occur where an optimum porosity 

 exists. Natural litter fuel beds appear to have low porosities and small changes can 

 cause large shifts in burning rate. 



LITERATURE CITED 



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