OPTIMUM ECONOMIC PIPE DIAMETER FOR PUMPING HERSCHEL-BULKLEY FLUIDS IN LAMINAR FLOW.

A method for determining optimum pipe diameter, for which total pumping system cost is minimum, has been derived for the transport of W. H. Herschel-R. Bulkley (H-B) fluids (power-law fluids wih a yield stress) in laminar flow. The method accounts for pipe system cost as a function of diameter, and pump station and operating costs as a function of power requirements. The optimum diameter can be estimated given rheological properties, fluid density, mass flow rate and economic parameters. Optimum diameter does not depend on system elevation or pressure energy difference when a linear relationship is used for pump station cost. Friction loss in fittings and valves can be ignored when the pipe length is much greater than the pipe diameter. Pump station cost has less influence than operating cost in determining the optimum diameter.