ISSN:: 1020.1265,98 Design and Construction of Capillary Rheometer

A capillary rheometer was designed and constructed to carry out studies on the flow behaviour of viscous non-Newtonian fluids. Two capillary tubes were attached to the pressure chamber which increase the accuracy of the rheological measurements ( power law index as well as consistency index). By employing two capillary tubes, the power law index can be calculated directly from the measuring values and the accuracy of consistency index increases as well. Capillary tubes with different diameters and various lengths can be used and a wide range of shear rates can be covered by using different tubes. Tests were conducted with solutions of sodium carboxymethyl cellulose (CMC) of different concentrations and various temperatures. The CMC solutions exhibited characteristics typical of power law model of non-Newtonian fluids. The measurements illustrated that the consistency index varies significantly with both concentration and temperature. Increasing concentration enhances consistency index while promoting temperature has a reverse effect. Also concentration has noticeable effect on power law Index. As concentration increases the power law index decreases. The effect of temperature on power law index is negligible