Phase change, interfacial momentum transfer

The interfacial momentum transfer due to phase change is defined by ... 

The conventional formulas for the interfacial momentum transfer due to phase change are defined in sect 3.3 for the different averaging methods commonly applied in chemical reactor analysis. The modeling concepts usually adopted for the different averages are mathematically similar, so we choose to present a representative interfacial momentum transfer term in the framework of the volume averaging method described in sect 3.4.1. 

In fluid mechanics the interfacial momentum transfer due to phase change (3.148) is normally expressed in terms of interfacial mass flux weighted quantities... 

For catalytic solid surfaces in packed beds and porous materials the speed of displacement of the interface is assumed to be zero, vi-Hk =0. For this reason the interfacial momentum transfer due to phase change can be reduced to ... 

The rather blurry picture of the gas-liquid interface makes it very difficult to parameterize the yk)Aj variable. Therefore, the interfacial momentum transfer due to phase change is generally neglected at these surfaces too. Further work is obviously required to improve our knowledge about these phenomena and to validate this model assumption. 

Interfacial momentum transfer due to phase change (N/m ) Interfacial momentum transfer caused by stresses (N/m ) Instantaneous mass flux of molecules of species of type c with respect to stationary coordinate axes (kg/m s)... 

---