Sequence of temperatures

Figure 4. Variable temperature flowing HP 129Xe NMR MAS spectra of xenon adsorbed in montmorillonite pillared with pyridinium ions. The Xe/N2/He mixture flow rate was 300 cc/min. The sequence of temperature steps progresses from bottom to top. The spectrum at 373K was after drying in a stream of flowing helium for 3 hrs at 373K.

Thus, in the idealised tubular reactor all elements of fluid take the same time to pass through the reactor and experience the same sequence of temperature, pressure and composition changes. In calculating the size of such a reactor, we are concerned with its volume only its shape does not affect the reaction so long as plug flow occurs. 

The catalysts were presulfided with a 10% H2S/H2 mixture and tested at a reactor pressure of 2000 psig and a hydrogen circulation of 5000 scf/B. Each catalyst was subjected to a standard sequence of temperatures and liquid hourly space velocities, ranging from 720-800°F and 0.5-2.0 hour l, respectively... 

III. El > Ez, Ez < Ei In the early stages of the reaction before much X has been formed it is important to make reaction (1) dominate reaction (2), so that a high temperature is called for. Later on in the course of the reaction it is reaction (3) which is to be emphasized at the expense of (4), and this requires a lower temperature. Hence a decreasing sequence of temperatures is desirable. 

Figure 8, Time sequence of temperature profiles of the front south of Nova Scotia taken by Batfish over —30 /i. A bimodal intrusion occurs in Panel 4 at...

Figure 3.12. Sequence of temperature profiles measured by Lidar at Bicarosse, France (from 19 00 to 23 00) showing the presence of gravity waves in the mesosphere. From Hauchecorne et al. (1987).

The kinetic parameters for coke combustion were obtained by fitting to eq. (14) the experimental data of weight loss rate, dC/dt, obtained in thermogravimetric equipment by working under a programmed sequence of temperature-time [9]. 

A typical schematic inlet stream temperature history is shown in Fig. 1. The temperatures were recorded on the oscillograph at a chart speed of 4 in./sec. Since the cool-down period was generally 20 sec or more in duration, much of the significance of the temperature fluctuations observed is lost on the time scale used in Fig. 1 therefore, actual temperature traces for typical time increments are reproduced in Fig. 2. From Fig. 1 it is evident that the temperature-time trace is initially very smooth, but fluctuates with time thereafter. A few seconds after the admission of fluid into the test section, saturation temperature appears momentarily. As the test section gradually cools down, liquid appears more frequently and persists for longer periods. These phenomena can be readily seen from the sequence of temperature traces shown in Fig. 2. From these observations, the following mechanisms of two-phase flow are postulated for pressurized cool-dowm. 

Second, there is no reproducibility of the resulting compositions in duplicate experiments. Third, die final products of the same gross composition reactions, for instance, R+2S or RS. 50+0-5S, are not always identical, and depend on the origin of the starting products and the sequence of temperature and pressure variation. With these principles, one can suggest that the powdered polysulfides prepared by different authors (see sect. 3.3) can hardly be related to equilibrium materials. A multiphase surface state of powders has a serious effect on many properties and, thus, merits detailed consideration here. It is apparent that special means must be used to provide data on the gross composition and the spatial variation of the sulfur content over the grain. 

Fig. 20.23 The upper curve represents a sequence of temperatures 8- 2 5°C (46 5-144-5°F) typical of a pasteurization process. The lower curve is the corresponding number of pasteurization units delivered (ordinate 0-3-2). Total pasteurization units = 40.

After setting up the experimental assembly, a typical procedure has to be undertaken which leads to sequences of temperature fields. 

FIGURE 52.11 Time course of the emission of isoprene (m/z 69), methanol (m/z 33), and (E)-2-hexenal (m/z 57) following exposure to high temperature of Phragmites leaves. The sequence of temperature is shown at the top part of the figure. Other C6 compounds are identified by the lines that represent (Z)-3-hexenal (m/z 81 + m/z 99) and the sum of (Z)-3-hexenol and (E)-2-hexenol (m/z 83 + m/z 101). NS, mean values nonsignificantly different from those recorded before treatment. (Reprinted with kind permission from Reference [21], Wiley-Blackwell Publishing Ltd.)... 

This condition can always be attained even if the return path cannot be devised in the simple manner of Fig. 8. For example, use may be made of a heat engine which absorbs heat from the prescribed heat bath at T and delivers heat into the S3nBtem at any necessary sequence of temperatures. 

Fig. 39. The density of states of the f-like band plotted for a sequence of temperatures. Solid curves represent N+(a>) for the upper band, and the dotted curve represents (V (to) for the lower band (Liu 1987,...

Fig. 9. Sequence of temperature profiles in the H2 oxidation on a Ni foil. The catalyst is not heated electrically. Dark areas are hot, there are two fronts emanating from the left and top which subsequently merge after [46].

A method was described for measuring the heat and rate of crystallisation following partial melting. The method uses a specific sequence of temperatures with a differential scanning calorimeter, and the melting and recrystallisation processes were confirmed by optical observations. The method was applied to poly(butylene terephthalate). The melting temperatures obtained from recrystallisation were used in the Hoffman-Weeks equation to deduce 236 C as the equilibrium melting temperature for PBTP. 22 refs. 

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