| 摘要: | 本研究以理論模式預測含有碳、氫、氧原子的可燃性物質隨著加入不同濃度的惰性物質之惰化效應。能量守恆與假設絕熱火焰溫度為定值來建立本研究預測模式。甲烷、丙烷、異丁烷、乙烯、丙烯、甲酸甲酯、二甲基醚、甲醇及丙酮等物質用來驗證本研究所提出的模式。N2、CO2、H2O、五氟乙烷(HFC-125)及三氯甲烷(CHCl3)為本研究所使用的惰性物質。
燃燒上限和下限的預測值與實驗值之平均相對誤差百分率都低於10 %，但是會過度地預測最小需氧量。本研究發現在預測燃燒上限時，燃燒產物由CO轉變成CO2的情形是不能忽略的，否則會產生很大的誤差。整體而言，除加入HFC-125和CHCl3外，本模式能有效地預測惰性物對於燃燒界限的影響性。
本研究認為至少需要四個濃度點，且在燃燒上限各物質實際的生成產物組成是必需的，才能準確地預測燃燒範圍。除了學術上的價值外，結果能被應用在真實製程的防火防爆設計，和降低製程可燃性物質在正常操作、儲存和運輸上的火災爆炸風險。
This study proposed a model to estimate inerting effect on flammability limits for organic compounds made up of carbon, hydrogen and oxygen. The energy balance and assumption of constant adiabatic flame temperature were used to establish model. Methane, propane, isobutane, ethylene, propylene, methyl formate, dimethyl ether, methanol and acetone were selected as examples to validate the proposed model. Nitrogen, carbon dioxide, water, 1,1,1,2,2-pentafluoroethane (HFC-125) and chloroform (CHCl3) were used as inert.
The mean absolute relative deviations between predictions and experiments are both less 10 % at LFL and UFL, but over estimating the LOC. Our results reveal that combustion products transfer from CO to CO2 should not be ignored in the prediction of UFL, otherwise the deviations would be considerable. Overall, the estimated results of this proposed model describe the experimental data well, except the case of adding to HFC-125 or CHCl3 flammable mixture.
We suggest that at least four points and the actual compositions of products at UFL are required for precisely predicting the flammable zone. In addition to academic values, the results will be applicable in preventing the fires and explosions in real process, and can reduce the risk of fire and explosion in normal operation, storage, and transportation of materials |
