Effect of Physical Properties on Accuracy Enhancement of Free Radical Polymerization Model in Tubular Reactors

In past decades free radical polymerization model in tubular reactors based on reacting flow of Computational Fluid Dynamics has been developed by implementing the method of moments (Zhou et al., 2001) in which physical properties of the fluid phase was mostly assumed to have constant values. However, in commercial reactors, vast temperature gradient of feed components, reacting mixture and heating or cooling operation were manipulated in order to control the reactor temperature. This gradient can be expected to significantly influence the predicted results. In the present work, physical property correlations as functions of temperature such as heat capacities and viscosity were combined with the CFD model in order to improve the accuracy and reliability of predicting the temperature profile in the reactor. In a case study, the developed model indicated that the variation of specific heat capacity (C-p) significantly affected the temperature profile of LDPE tubular reactor. In turn, this effect also influenced the determination of the safe window for commercial operation with respect to ethylene decomposition.