A new model based on adiabatic flame temperature for evaluation of the upper flammable limit of alkane-air-CO_2 mixtures

摘要

Highlights•A new model based on adiabatic flame temperature has been proposed.•A linear relationship exists between dilution ratio and calculated adiabatic flame temperature.•The flammable zones of n-butane-CO2and isopentane-CO2were measured to test effectiveness of the VAFT model.•The average relative differences are less than 3.51% at upper flammability limit for VAFT model.AbstractFor 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-CO2mixture 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-CO2and isopentane-CO2mixtures 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.