Kinematic viscosity can be measured using a viscometer because of the relationship presented in the Hagen-Poiseuille law, which expresses that the pressure drop is due to gravity, dynamic viscosity, and kinematic viscosity. Pressure is negligible on liquid-phase fluids, so it does not factor into this experiment. Temperature, density, and composition can create changes in the deformation of the flow. This ratio is unique to kinematic viscosity, which enables the interpolation for an unknown variable by considering two variables, kinematic viscosity and concentration. The ratio of shear stress to the shear rate is the dynamic viscosity of a fluid, which is a measure of the resistance to deformation in laminar flow for a Newtonian fluid. Kinematic viscosity is the ratio of dynamic viscosity to density. In this experiment, a Cannon-Fenske viscometer will be used to measure the viscosities of several propylene glycol solutions to determine the relationship between viscosity and composition. These systems are best for materials with low viscosity, since this system minimizes shear stress, but the system is also harder to operate routinely due to issues with cleaning and needing larger volumes of fluid 1. Couette systems use a cup and filling material, and the fluid flows in between the two 1. Parallel plate systems use two parallel plates and is ideal for measuring across temperature gradients, allowing a smooth transition 1. Different measuring systems exist as well, with the standard being a cone and plate system, where fluid flows under the cone shape and over the plate, in order to minimize shear stress 1. These viscometers make use of the flowing force of the fluid, and they can use either a spring system or a digital encoder system 1. Rotational viscometers operate by applying shearing forces and measuring the time it takes a flowing 1. The standard method of measuring viscosity is through a glass tube viscometer, which estimates viscosity by measuring the amount of time it takes fluid to flow through a capillary tube made of glass 1. A variety of viscometers are used to obtain the most accurate readings of experimental materials. Viscosity is a measure of a fluid's resistance to flow, and it is a useful parameter in the design of efficient product processing and quality control in a wide range of industries. Dooley, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |