Pumps viscosity behavior

Figure 15.3 shows a typical time versus consistency graph for a permafrost-sealant test composition. The low initial Be ensures a low yield stress and pumping viscosity. The increase in Be is gradual, indicating slow dissolution of MgO and wollastonite in the solution. As the Be increases, its rise to 70 is rapid, and the time versus Be curve is almost vertical. Such behavior ensures that the slurry, once placed, will set rapidly. 

Many materials are conveyed within a process facility by means of pumping and flow in a circular pipe. From a conceptual standpoint, such a flow offers an excellent opportunity for rheological measurement. In pipe flow, the velocity profile for a fluid that shows shear thinning behavior deviates dramatically from that found for a Newtonian fluid, which is characterized by a single shear viscosity. This is easily illustrated for a power-law fluid, which is a simple model for shear thinning [1]. The relationship between the shear stress, a, and the shear rate, y, of such a fluid is characterized by two parameters, a power-law exponent, n, and a constant, m, through... 

While the EHD apparatus simulates industrial bearings and provides information on lubricants performance, it has serious drawbacks for the spectroscopic studies of liquid crystal behavior under shear. The temperatures in the conjunction region vary with position and depend on load, speed, viscosity, etc., but cannot be controlled arbitrarily. The gap widths are similarly determined by the same parameters and cannot be maintained arbitrarily. Therefore shear rates (speed/gap width) are not easily controlled. As Fig. 7 shows, film thicknesses and tractions for a typical liquid lubricant vary with spe because more fluid is pumped in the EHD contact at high speeds while higher temperatures are generated, which cause the viscosity to decrease in ordinary fluids. As was shown, liquid crystals can behave differently because of phase changes. 

The dynamic behavior of ionic liquids is important for both practical and theoretical reasons. From a practical standpoint, bulk transport properties such as the viscosity, self-diffUsivity, thermal conductivity and electrical conductivity govern the effectiveness of these liquids in any application. For example, mass transfer of reactants and products is critical to the performance of ionic liquid solvents, and is highly correlated with the self-difiiisivity and viscosity. Viscosity also plays a role in the cost of pumping the liquid and its performance as a lubricant. Thermal conductivity is a key parameter for thermal fluid applications, and electrical conductivity is obviously important in electrochemical applications. 

One of the most easily observed macroscopic properties of colloidal systems is their flow behavior, and it may range anywhere between a low viscous fluid and a gel state. The rheological properties and, in particular, the viscosity of microemulsions are macroscopically observable parameters that characterize a given system. Of course, the viscosity is a relevant quantity for many practical applications of microemulsions. For instance, pumping such systems might be of interest in their application, and here viscosity plays an important role. 

This model yields good predictions (straight lines shown in Figure 3) for the apparent viscosity. The model parameters are needed to calculate the pressure required for pumping the emulsified acid. The power-law index (n) slightly increases (from 0.62 to 0.68) as temperature is increased to 45 °C [14]. As a result, the emulsified acid approaches Newtonian behavior at higher temperatures. Field data [14, J5] indicate that the... 

Strictly speaking, one cannot insert a power law melt viscosity in the Newtonian throughput-pressure reiationship, as discussed earlier in Section 8.2.1. Thus, Eqs. 8.81 and 8.83 are not 100% accurate. However, they are much more accurate than predictions based on pure Newtonian behavior, because the latter can cause substantial errors see, for instance. Figs. 7.62 through 7.66. The dimensionless maximum pressure is shown as a function of the pump ratio Xp in Fig. 8.39. 

In the area of personal care, solution rheology directly affects how a cosmetic product behaves. In this way, associative polymers can influence a cosmetic s aesthetic properties. Perhaps more importantly, they can influence the appearance of the product, the spreading behavior, the film thickness, and the feel of cosmetics from lotions to gels to shampoos. From the consumer s perspective, products that appear stringy (pituitous) or that ball up on application (pilling) are undesirable (72). Good viscosity control can impart a perceived increase in product concentration that the consumer considers beneficial. A low-viscosity product delivered from a bottle or pump is unacceptable, yet low-viscosity products are a necessity for products that are atomized (aerosols). In most cases, the viscosity manipulation is partly the result of appropriate polymer selection. 

For the production of fuel cell electrodes via a doctor blade process, a Newtonian behavior of carbon-based inks is very desirable. This means, that the viscosity is not changing, no matter what shear stress is applied on the ink or slurry, what is leading to the fact, that the ink or slurry can be pumped from a storage vessel to the doctor blade with low changes in viscosity. The low change of viscosity leads to a very constant flow of ink to the doctor blade. 

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