For security issue of alkane used in Organic Rankine Cycle, a new model to evaluate the upper flammability limits for mixtures of alkanes, carbon dioxide and air has been proposed in present study. The linear relationship was found at upper flammability limits between molar fraction of diluent in alkane-CO₂ mixture and calculated adiabatic flame temperature. The prediction ability of the variable calculated adiabatic flame temperature model that incorporated the linear relationship above is greatly better than the models that adopted the fixed calculated adiabatic flame temperature at upper flammability limit. The average relative differences between results predicted by the new model and observed values are less than 3.51% for upper flammability limit evaluation. In order to enhance persuasion of the new model, the observed values of n-butane-CO₂ and isopentane-CO₂ mixtures measured in this study were used to confirm the validity of the new model. The predicted results indicated that the new model possesses the capacity of practical application and can adequately provide safe non-flammable ranges for alkanes diluted with carbon dioxide.

中文翻译：

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基于绝热火焰温度的新模型，用于评估烷烃-空气-CO ₂混合物的易燃上限

针对有机朗肯循环中使用的烷烃的安全性问题，本研究提出了一种评估烷烃，二氧化碳和空气混合物可燃性上限的新模型。在烷烃-CO ₂中稀释剂的摩尔分数之间的可燃性上限之间发现线性关系混合物并计算绝热火焰温度。结合了上述线性关系的可变绝热火焰温度模型的预测能力大大优于采用可燃上限的固定绝热火焰温度模型的预测能力。对于可燃性上限评估，新模型预测的结果与观测值之间的平均相对差异小于3.51％。为了增强对新模型的说服力，正丁烷-CO ₂和异戊烷-CO ₂的观测值在这项研究中测量的混合物被用来确认新模型的有效性。预测结果表明，该新模型具有实际应用的能力，可以为二氧化碳稀释的烷烃提供足够的安全，不可燃范围。