Desenvolvimento e avaliação de metamodelos para cálculo de extensão de atmosfera explosiva em áreas classificadas.

Abstract

Hazardous extent predictions that ensure process safety while avoiding overprediction has been an enormous challenge for hazardous area classification. Specific scenarios can be addressed to build metamodels capable of predict rapidly and accurately hazardous extent. Therefore, this work aims t o propose a model to predict h azardous e xtent in fla mmable a tmospheres b y metamodeling construction and validation. Considering gas leakages in an open environment and without obstructions, varying the factors storage pressure and temperature, orifice diameter, molar mass, wind velocity and lower explosive limit. Different techniques were used to obtain the metamodel, a s s imple l inear r egression, K riging mo delling, a nd a n interpolation mo del based on w eighted harmonic mean. Every metamodel was built by u sing data obtained from Computational F luid D ynamics (CFD) s imulation. T he s imple linear regression model w as coupled with an axial decay velocity model using an algorithm to avoid the prediction errors due to the nonmonotonic wind effects. The suggested algorithm, called by modified empirical model, calculated the hazardous extent value with a coefficient of determination (R2) equals to 0,9842 and a Root Mean Square Error (RMSE) of 0,0151 for a dataset of 600 cases of generic gases release. The proposed model was also validated for 60 cases of hydrogen release, giving a R2 equal to 0,9829 a nd a RMSE of 0,0680. A c ase o f s tudy c onsidering different r elease scenarios was done, comparing the modified empirical model against analytical models and with the IEC 60079101 (2020). The modified empirical model showed the best results when compared with the other models, reflecting enough evidence to support the model accuracy in predict hazardous extent.