Resistance coefficients of fittings for power-law fluids in laminar flow

The calculation of head loss in valves and fittings is highly important to design food engineering processes under several pumping conditions. Neverth eless, there are few data reported to predict pressure loss in accessories for nonNewtonian fluids in laminar flow, usually observed in many viscous f luid foods. In this study, experimental data of pressure drops as a functio n of the generalized Reynolds number were obtained to determine the resista nce or friction loss coefficient(k(f)) of power-law fluids while pumped thr ough 1-in. diameter stainless steel valves (butterfly and globe), and an as sembly of four 90 degrees bends. Aqueous dispersions of carboxymethylcellul ose were used as a model of a shear thinning fluid. Results showed that for all the accessories evaluated, the k(f) values hold an inverse function wi th the generalized Reynolds, using the classical log-log plot. Results are in agreement with data reported in the literature for Newtonian and power-l aw fluids. The correlations obtained in this study were compared with resul ts in previous works and they were found to be within the range reported.