Design According To Leungs Equilibrium Model

The modified homogeneous equilibrium rate model according to Leung [101] is probably the most widely accepted model for the design of emergency relief situations 

The optical impression of a bubble flow system is characterized by a great number of finely dispersed small bubbles, while in the case of the chum turbulent flow a growing bubble size is observed on its way to the liquid surface. 

If this estimation shows that the fiee board volume is not completely filled with the boiling reaction mixture because the liquid level prior to venting was very low, the design for single phase venting may be conducted. 

In the other case the vapour mass fiaction at the relief device entrance must be estimated taking into account the flushing flow hypothesis. This allows the calculation of the so-called entropy parameter ro, which is required for the determination of the critical mass flow density G.  

A common prerequisite to the application of all these equations is the evaluation whether the ratio of set pressure of the relief device to the counterpressure is high enough to ensure critical flow conditions in the vent area. 

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