Evaluating relief events in binary mixtures with dynamic simulations

Relieving rates in ethanol/water and ethylene glycol/water mixtures were investigated using dynamic models of an emergency relief scenario due to an external heat source. A commonly used shortcut method was compared to two rigorous calculation methods—one using ideal conditions and another using non-ideal conditions. In several cases, the shortcut method provides a reasonable estimate compared to the rate predicted by the more rigorous methods. However, in many cases the shortcut method over or under-predicts the required relieving rate—sometimes by a significant amount. Several discrepancies are also noted between non-ideal and ideal conditions. This study demonstrates that each multi-component mixture must be carefully considered before sizing emergency relief systems and devices.