Solidification point parameters

While this may appear even more cumbersome than Eq. (3.41), it contains some parameters that are directly measurable such as the interfacial surface energy, y, and the heat of fusion, AH, but more importantly, it contains the temperature difference (T, — T), which is the degree of undercooling—that is, how far the temperature is below the melting (solidification) point ... 

Industry uses a number of analytical methods to characterize oils and fats, in terms of a number of parameters which include moisture, titer (solidification point), free fatty acid, unsaponifiable material, iodine value, peroxide value, and color. Moisture content of the oils and fats is an important measure for storage stability at elevated temperature because it facilitates hydrolysis which in turn impacts odor and color quality. Titer is a measure of the temperature at which the material begins to solidify, signifying the minimum temperature at which the material can be stored or pumped as a fluid. Free fatty acid is a measure of the level of hydrolysis the oils and fats have undergone. Increased fatty acid content usually negatively impacts product color stability because fatty acids are more susceptible to oxidation. Unsaponifiable material is a measure of the nontriglyceride fatty material present, which affects the soap yield of the material. The iodine value is a measure of the amount of unsaturation present in the oils and fats. Peroxide value is a measure of the... 

The transition to the continuum fluid may be mimicked by a discretization of the model choosing > 1. To this end, Panagiotopoulos and Kumar [292] performed simulations for several integer ratios 1 < < 5. For — 2 the tricritical point is shifted to very high density and was not exactly located. The absence of a liquid-vapor transition for = 1 and 2 appears to follow from solidification, before a liquid is formed. For > 3, ordinary liquid-vapor critical points were observed which were consistent with Ising-like behavior. Obviously, for finely discretisized lattice models the behavior approaches that of the continuum RPM. Already at = 4 the critical parameters of the lattice and continuum RPM agree closely. From the computational point of view, the exploitation of these discretization effects may open many possibilities for methodological improvements of simulations [292], From the fundamental point of view these discretization effects need to be explored in detail. 

Mathematical designing of an experiment has been applied to mathematical modeling of solidification and hardness of concrete as a function of three basic factors Xi-cement consumption, kg/m3 X2-percentage of sand in filler mixture, % and X3-water consumption, 1/min. This parameter was measured as response yi-concrete solidification, s. The cement of the same brand and the sand from the same supplier have been used in all design points. A mixture 101 in volume was mixed manually for 3 min and a 7 1 volume for 2.5 min. Samples of 10 x 10 x 10 cm were prepared on a vibration table with amplitude of 0.45-0.50 mm, frequency of 2800 min 1 and under pressure of 80-100 kp/cm2. Concrete solidification was measured 10-15 min after formation of samples by GOST 10181-62. Basic experiment was done by FUFE 23, as shown in Table 2.161. 

The Effect of the Polymer-Solvent-Precipitant System on Membrane Structure and Properties. The effect of the polymer on membrane structure and properties is closely related to the solvent used in the casting solution and the precipitant. The solvent and the precipitant used in membrane preparation determine both the activity coefficient of the polymer in the solvent-precipitant mixture and the concentration of the polymer at the point of precipitation and solidification. The polymer-solvent-precipitant interaction can be approximately correlated in terms of the disparity of the solubility parameter of polymer and solvent. 

The specific shape of the bubble (Fig. 3.8) depends on the combined influence of several process parameters. In general, the bubble usually has a small diameter and large thickness at the die exit and transitions to a large diameter and small thickness as it moves upward toward solidification. Above some point, the geometry is frozen-in and remains virtually constant. 

When the formulated solution contains essentially saline or organic solutes that crystallize easily, the interstitial phase will crystallize out abruptly as an eutectic or a mixture of eutectics. The crystallization results in an immediate hardening of the frozen system, which becomes fully rigid. At this point, the system has reached its maximum temperature for complete solidification (eutectic point, Te), which is a basic parameter of the freeze-drying process. 

There is, however, another use for data of the type of Fig. 11-11. That use is to estimate the reduced radius at which the solidAiquid interface is positioned for various z values. All that is needed in such as case is some rough measure of complete solidification, such as a quench point generally measured as a plant parameter. The rough measure of z is then taken as the value for the ft for solidification (ft = 0.832). Then, for example, for the case in which the liquid/ solid interface is at an r/R of 0.5 (ft = 0.510), the following will hold ... 

The blown film process is known to be difficult to operate, and a variety of instabilities have been observed on experimental and production film lines. We showed in the previous chapter (Figure 10.10) that even a simple viscoelastic model of film blowing can lead to multiple steady states that have very different bubble shapes for the same operating parameters. The dynamical response, both experimental and from blown film models, is even richer. The dynamics of solidification are undoubtedly an important factor in the transient response of the process, but the operating space exhibits a variety of response modes even with the conventional approach of fixing the location of solidification and requiring that the rate of change of the bubble radius vanish at that point. 

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