Computational methodology for determination of head loss in both laminar and turbulent regimes for the flow of high concentration coal ash slurries through pipeline

ABSTRACT: Flow of fine coal ash slurries at high concentrations (60–70% by weight) was analyzed using the commercial computational fluid dynamics (CFD) package FLUENT. Rheological properties of high concentration slurry show that the slurry behaves as a non-Newtonian fluid and exhibits Bingham plastic behavior. The predicted results for pressure drop as a function of flow velocity for the slurry flow at different concentrations are found to be in good agreement with experimental data reported in the literature. The k-ω Shear Stress Transport (SST) model was found to give better results in the turbulent regime and is consistent with the observations reported in literature. The predicted results for pressure drop were used to calculate the friction factor at various Reynolds and Hedstrom numbers. The methodology developed will help the design of high concentration ash slurry disposal systems based on the measured values of rheological parameters of the slurry. The rheological parameters account for the variation of the particle size distribution in the coal ash and thus the effect of particle size distribution on the head loss in the pipe line was established indirectly.