A Systematic Algorithm to Compute Hazardous Area Extent for Two-Phase Releases Based on an Improved Low-Dimensional (Simple) Dispersion Model

This contribution aims at systematically determining the extent of classified areas in two-phase releases of pure components. To this end, a novel algorithm is proposed to ensure all proper steps are taken toward accurately computing the required properties of the resulting cloud. The intended framework is based on a refined one-dimensional dispersion model that accommodates (1) the influence of the vapor component on the energy balance of the two-phase jet model; (2) new decay constants to calculate velocity, concentration, and temperature profiles; (3) a new normalization ratio to compute the temperature along the centerline; and (4) a new correlation for the entrainment coefficient in the two-phase region. It was found that the entrainment coefficient ( \({\alpha }_{1}\) ${\alpha }_1$ ) correlates linearly with the orifice Reynolds number ( \(R{e}_{e}\) $R{e}_e$ ), with a coefficient of determination \({R}^{2}>0.98\) $R^2>0.98$ . Altogether, these modifications produced results that are in very good agreement with (scarce) experimental data available in the literature. The calculated release rates were only (on average) 9% off from measured data. The temperature profiles at the centerline compared well with the experimental data, with very small relative squared error \(RSE<0.10\) $RSE<0.10$ . The hope is that this simple algorithm can predict within reasonable precision the reach of the hazardous cloud in open field situations. In particular, it was observed an average reduction of about 55% in the hazardous extent vis-à-vis the computations by the IEC 60079–10-1.