クリブモデル火災の消火諸現象の定量化

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書誌事項

タイトル別名
  • Quantitative Treatment of Extinction Phenomena of Crib Model Fire
  • クリブ モデル カサイ ノ ショウカ ショ ゲンショウ ノ テイリョウカ

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Many reports are available on the extinction of wood fire, especially on wood crib fire, still they are not enough for systematic appreciation of extinction phenomena and mechanism, we need basic rules that govern extinction. <br>In order to investigate these problems, in this research, water was dripped on the top flat surface of crib, then one could avoid the drain-off ideally until the extinction is almost achieved, reducing one difficult item for analysis. <br>By this method, it was found that there is very clear relation among the extincted number of layers Ne , water application rate P and the period of water application t as follows; <br>Ne = αPmtn<br>where α is a function solely of the weight loss ratio φ and m, n are constants respectively. <br>The mass balance equilibrium can then be written as; <br>I = p − (r +e) <br>where I is the rate of mass increase, r is the burning rate during extinguishing, and e is the evaporation rate of water. <br>And also, it was found that I is merely a function of p neither depending on φ nor t, namely, <br>I = ap−b ≈ap−rM<br>where a, b are constants. <br>and r could be given properly by the following equation; <br>r = rM N0−Ne /N0<br>Here rM is the burning rate just before water application, and N0 is the number of layers. <br>Then e was derived as follows; <br>e = p (1−a)+rM αPm/N0 tn<br>and because the total water evaporated E is the integration of e with respect to t, then; <br>E = ∫te0edt = [p (1−a) + rM /n+1]te<br>Furthermore, the fuel lost during extinguishing can be obtained by integrating r as follows; <br>ΔM = ∫te0rdt = n/n+1 rMte ≈ n/n+1 r0te<br>ΔM was experimentally measured and showed good agreement with the calculated value. <br>The relative difficulty of extinction, such as by carbon formation or crib height, could also be calculated quantitatively. <br>The critical water application rate P, was defined as; <br>M0(1−φ−c)/rM > (N0/α)1/nP−m/n<br>where M0 is the original crib weight, and c is the char yield. <br>and also showed good agreement with measured values in constant flaming combustion area.

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