Heat transfer and multiphase flow with hydrate formation in subsea pipelines

A new predictive model is developed to analyze hydrate formation with coupled heat and mass transfer in a pipe. The model tracks the particle velocity at each time step, while estimating the growth of the hydrate using the change in Biot number and dimensionless time. The numerical results are validated experimental results for R134a hydrates. The effects of change in heat transfer ratio, phase change number, superheating, and pipe diameter on hydrate formation are reported in this paper. The results indicate that higher heat transfer ratio between the internal and external fluids reduces the possibility of hydrates creating a blockage in the pipeline. The pipes with smaller diameters are also found to reduce the possibility of hydrate formation at a constant pipeline pressure. The results show that at temperatures below −10 °C, changing thermophysical properties have limited impact on the rate of hydrate formation in the pipe.