An Empirical Approach to Correlate Power Law Fluid Parameters Obtained from Low Shear Rate Rotational Viscometers and Tube Flow Viscometers

Abstract

Methods for pressure drop estimation of non-Newtonian power law fluids in tube flow are reviewed. Pressure gradients and the corresponding mass flow rates of five different non-Newtonian fluid foods: 1% solutions of sodium alginate and CMC, 1. 5% CMC solution, two different tomato ketchups, oyster sauce, in four different diameter stainless steel tubes ranging from 7. 51 to 16. 34 mm i. d. were recorded using a continuous flow tube viscometer capable of operating in both transient and continuous flow modes. The fluids were pseudoplastic in nature and followed the power law model. The flow was confined to the laminar flow regime and appreciable slippage occurred in all cases. Power law parameters, based on tube flow and low shear rate rotational viscometer were determined and compared. These power law parameters failed to give the classical relationships proposed by Dodge and Metzner [1]. Empirical equations were developed to correlate power law parameters based on low shear rate rotational viscometer to the ones based on tube flow viscometer. Pressure drop estimations based on the empirical equations followed the experimental values with 139 average absolute error.