Cooling experiment

Qui, Yangeng and Rasmuson, A.C., 1994. Estimation of crystallization kinetics from batch cooling experiments. American Institute of Chemical Engineers Journal, 40, 799-812. 

A2. Adorni, N., Bertoletti, S., Lesage, J., Lombardi, C., Peterlongo, G., Soldaini, G., Weckermann, F. J., and Zavattarelli, R., Results of wet steam cooling experiments pressure drop, heat transfer and burnout measurements in annular tubes with internal and bilateral heating, CISE-R.31 (1961). 

Figure 135 shows a temperature history in a cooling experiment. In Figure 136 the time when the temperature at the different thermocouples in the experiment dropped below the phase change temperature is compared with predictions from different models. 

For instance, the main process parameter in a heating/cooling experiment is the temperature. 

In a stepwise cooling experiment, texp is equal to the time spent at every temperature step... 

Figure 12.16 Screw speed, pressure at the entry to the first-stage meter (PI), and discharge pressure for the screw cooling experiment...

Figure 4.5 shows the liquidus and solidus for In-Pb determined during cooling from the liquid the solidus, in this case, is a non-equilibrium boundary. This was demonstrated by Evans and Prince (1978) when they atmealed as solidified alloys for several hours just below their measured solidus. On re-heating melting occurred at a higher temperature than had been measured by DTA. The samples were then annealed for several hours just below the new measured melting temperature before being heated until melting was just observed again. The cycle was repeated until the solidus temperature became reproducible and the temperature then plotted as the true solidus. This is compared with the apparent solidus on the initial cooling experiment in Fig. 4.5. This paper shows the problems that can occur with...

Schlenz H., Kroll H., and Phillips M.W. (2001) Isothermal annealing and continuous cooling experiments on synthetic orthopyroxenes temperature and time evolution of the Fe, Mg distribution. Eur. J. Mineral. 13, 715-726. 

Figu re 9.16 Cooling experiment in a full-scale reactor. The heat balance is calculated between the two instants, t, and t2. 

This gives a linear plot where the slope is the inverse of the thermal time constant. An example of such a linear fit is represented in Worked Example 9.1. Since the mass (M), the specific heat capacity of the contents (c P), as well as the heat exchange area of the reactor (A) are known, the only unknown is the overall heat transfer coefficient (U). As during heating and cooling experiments, the reactor... 

A 2.5 m3 stainless steel stirred tank reactor is to be used for a reaction with a batch volume of 2 m3 performed at 65 °C. The heat transfer coefficient of the reaction mass is determined in a reaction calorimeter by the Wilson plot as y = 1600Wnr2KA The reactor is equipped with an anchor stirrer operated at 45 rpm. Water, used as a coolant, enters the jacket at 13 °C. With a contents volume of 2 m3, the heat exchange area is 4.6 m2. The internal diameter of the reactor is 1.6 m. The stirrer diameter is 1.53 m. A cooling experiment was carried out in the temperature range around 70 °C, with the vessel containing 2000 kg water. The results are represented in Figure 9.16. 

The characteristics of industrial reactors are identified in a series of heating and cooling experiments, as described in Section 9.3.4, building a dynamic model of the reactor ... 

Table 9.7 Two points extracted from the cooling experiment.

Fig. 9.19 Helical ribbon of LDPE, after it was taken off the screw following a cooling experiment. The numbers indicate turns downstream the hopper and cross sections for examination obtained by slicing it perpendicular to the flights, as shown by the broken line.

Fig. 9.20 Cross sections obtained from cooling experiments of a 2.5-in-diameter 26.5 length-to-diameter ratio screw extruder. Material rigid PVC. Operating conditions are listed in the figure Tb is the barrel temperature, N the screw speed, P the pressure at the die, and G the mass flow rate. Numbers denote turns from the beginning (hopper side) of the screw. The screw was of a metering type with a 12.5 turn feed section 0.37 in deep, a 9.5 turn transition section, and a 4.5 turn metering section 0.127 in deep. [Reprinted by permission from Z. Tadmor and I. Klein, Engineering Principles of Plasticaling Extrusion, Van Nostrand Reinhold, New York, 1970. The experiments were carried out at the Western Electric Engineering Research Center, Princeton, NJ.]...

Fig. 9.21 Cross sections obtained from cooling experiments of a 2.5-in-diameter, 26.5 length-to-diameter ratio screw extruder. Material PP. Operating conditions are listed in the figure (G — 96.8 lb/h). Symbols and screw descriptions as in Fig. 9.20.

Fig. 9.22 Cross sections from cooling experiment. For details see Figs. 9.20 and 9.21. Material nylon.

Fig. 9.25 Cross sections obtained from a cooling experiment of an 8-in-diameter extruder. Material and operating conditions indicated in the figure. [Reprinted by permission from Z. Tadmor and I. Klein,...

Fig. 9.26 Idealized cross-section compared to (a) the cross-section from a PVC cooling experiment and (b) the cross-section from an LDPE cooling experiment. [Reprinted with permission from Z. Tadmor and I. Klein, Engineering Principles of Plasticating Extrusion, Van Nostrand Reinhold Book Co., New York, 1970.]...

As mentioned earlier, the melting mechanism in screw extruders was first formulated by Tadmor (29) on the basis of the previously described visual observations pioneered by Bruce Maddock. The channel cross section and that of the solid bed are assumed to be rectangular, as in Fig. 9.26. The prediction of the solid bed width profile (SBP), that is the width of the solid bed X as a function of down-channel distance z, is the primary objective of the model, which can be experimentally verified by direct observation via the cooling experiment of the kind shown in Figs. 9.20-9.25. As shown by Zhu and Chen (40), the solid bed can also be measured dynamically during operation by equipping the extruder with a glass barrel. 

Existing correlation equations for calculating the heat transport parameters were obtained from heating or cooling experiments without reactions and assuming plug flow they therefore permit only a semiquantita-tive evaluation. This is adequate for qualitative comparison of catalyst structures. 

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