Temperature increase due

Substances containing a significant porosity also show an increasing photon transfer of energy as the temperature increases due to the superior n ansmis-sivity of infra-red photons tlrrough the pores over the sunounding solid. 

Oil recovery from underground reservoirs can be improved by injection of water and pressing of oil to the surface. This secondary oil recovery process is relatively cheap though not always successful. Further, however more expensive, methods are the so-called tertiary oil recovery processes whereby the viscosity of the oil is lowered by mixing with low viscous oils or gas, or by temperature increase due to injection of steam, and where the viscosity of the pressing water layer is increased or the surface tension between water and oil is decreased via addition of surfactants. 

Is any heat generated during the mixing or physical processing of substances YES Some temperature increase due to mechanical energy of screw conveyor... 

Excess benzene is always used in the reactors, also for two reasons. First, the benzene acts like a heat sponge, mitigating the rate at which the temperature increases due to the exothermic reaction. Second, excess benzene helps eliminate some of the undesirable side reactions that can take place, mainly the formation of di- or tri-isopropyl benzene (benzene hooking up with two or three propylenes) or other miscellaneous compounds. 

The results of the calculations shown in Fig. 2.32 represent a complete quantitative solution of the problem, because they show the decrease in the induction period in non-isothermal curing when there is a temperature increase due to heat dissipation in the flow of the reactive mass. The case where = 0 is of particular interest. It is related to the experimental observation that shear stress is almost constant in the range t < t. In this situation the temperature dependence of the viscosity of the reactive mass can be neglected because of low values of the apparent activation energy of viscous flow E, and Eq. (2.73) leads to a linear time dependence of temperature ... 

The activation energies for the electronic conductivity increase with decreasing p0i as the contribution from the ionic conductivity to the total conductivity increases. The maximum conductivity observed in Pq2 = 1 atm is 14 S cm-1 at 400°C. Above 400°C, the conductivity falls as the temperature increases due to the decrease of the concentration of electron holes as the concentration of oxygen vacancies increases at elevated temperatures according to Eq. I5... 

The scenario presented here was developed by R. Gygax [1, 2]. Let us assume that while the reactor is at the reaction temperature (TP), a cooling failure occurs (point 4 in Figure 3.2). The scenario consists of the description of the temperature evolution after the cooling failure. If, at the instant of failure, unconverted material is still present in the reactor, the temperature increases due to the completion of the reaction. This temperature increase depends on the amount of non-reacted material, thus on the process conditions. It reaches a level called the Maximum Temperature of the Synthesis Reaction (MTSR). At this temperature, a secondary decomposition reaction may be initiated. The heat produced by this reaction may... 

Presently there is no direct quantitative measure of the probability of occurrence of an incident, or in the case of thermal process safety, of the occurrence of a runaway reaction. Nevertheless, if we consider the runaway curves presented in Figure 3.3, the two cases presented are very different. In case 1, after the temperature increase due to the main reaction, there is enough time left to take measures to regain control or recover a safe situation. If we compare the probability of runaway in both cases, it becomes clear that the probability of triggering the runaway is higher in case 2 than in case 1. Thus, while we cannot easily quantify probabilities, we can at least compare them on a semi-quantitative scale. 

The beneficial effect of the rhodium catalyst was proved by experiments at a reactor which was coated only with alumina. However, full conversion was also achieved at 1 000 °C, but along with inferior selectivity. Decreasing the residence time was beneficial for both conversion and hydrogen selectivity at the reactor impregnated with rhodium. This was explained by a temperature increase due to an increased rate of the combustion reaction, which in turn propagated the reforming reactions. 

As a result, no temperature increase due to the exothermal chemical process was observed. With this single-channel reactor, a phosgene productivity of 3.5 kg per year is projected for continuous operation. 

Figures 7.13 and 7.14 give results using the FS2 flowsheet with the furnace for this hot-reaction case. Figure 7.13 shows that a 10% decrease in recycle flowrate can be handled, but a 20% decrease produces a reactor mnaway. This occurs despite the fact that the reactor inlet temperature increases only slightly ( 0.5 K) during the transient. Figure 7.14 gives results for changes in the setpoint of the reactor inlet temperature controller. Rather surprisingly, inlet temperature can be increased by 2 K without a runaway. This is unexpected since the isolated reactor (Fig. 7.12) showed a runaway with a +2 K change in Tm. The difference may be due to the effect of pressure. In the isolated reactor simulation, pressure is held constant at 50 bar. In the simulation of the whole process, pressure drops as reactor temperature increases due to the increased consumption of reactants. Since the reaction rate depends on the square of the total pressure (P2), the decrease in pressure lowers the reaction rates. However, a 3 K increase cannot be handled.

Measurements of the characteristics of various electrolyte compositions and the pure salts are reported by some authors [266,267,282], At 750°C the standard decomposition potentials of the electrolyte components are [282] MgCl2 -2.51 V NaCl -3.22 V KC1 -3.27 V LiCl -3.30 V CaCl2 -3.33 V BaCl2 -3.40 V. Codeposition of sodium or calcium will thus occur only by depletion of MgCl2 (<3%). This lowers the current efficiency and causes a temperature increase due to the recombination of sodium and chlorine. 

At various temperatures ranging from 200 to 300 °C, fso-propyldichloro-silane was obtained in the highest yield at 220 °C, but decreased as the reaction temperature increased due to the decomposition of iso-propyl chloride. Under these reaction conditions, the yield of fso-propyldichloro-silane was higher compared to those obtained from the direct reaction without hydrogen chloride addition, indicating that the decomposition of iso-propyl chloride was suppressed as expected. The yields generally increased with increased ratios of hydrogen chloride to /so-propyl chloride. 

The extruder might look like Figure 13-9. The feed, which is viscous and partly solid, enters at the left where it is picked up by the screw and thoroughly mixed. The screw causes the pressure to rise as the feed moves to the right. At the same time, temperature increases due to viscous dissipation. At the end of the extmder, the hot and cooked material moves through... 

Other errors, which could influence the results obtained, are, for example, wall effects ( slipping ), the dissipation of heat, and the increase in temperature due to shear. In a tube, the viscosity of a flowing medium is less near the tube walls compared to the center. This is due to the occurrence of shear stress and wall friction and has to be minimized by the correct choice of the tube diameter. In most cases, an increase in tube diameter reduces the influence of wall slip on the flow rate measured, but for Newtonian materials of low viscosity, a large tube diameter could be the cause of turbulent flow. ° When investigating suspensions with tube viscometers, constrictions can lead to inhomogeneous particle distributions and blockage. Due to the influence of temperature on viscosity (see Section Influence Factors on the Viscosity ), heat dissipated must be removed instantaneously, and temperature increase due to shear must be prevented under all circumstances. This is mainly a constructional problem of rheometers. Technically, the problem is easier to control in tube rheometers than in rotating instruments, in particular, the concentric cylinder viscometers. ... 

Many studies of the thermal stability of this reactant have been completed, due to its technical use as a primary explosive. Four polymorphic forms exist [12] of which the orthorhombic a-form is the most stable. The other forms can be prepared under specific conditions [12], At high temperatures (above 613 K) the reaction accelerates to detonation. This autocatalytic process has been attributed [54] to an increased concentration of defect sites, rather than a mechanism controlled primarily by temperature increases due to self-heating. 

Particle resistivity decreases as gas temperature increases due to enhanced volume conductivity. Resistivity may also decrease as gas temperature decreases if surface conditioning agents such as moisture or acid gases are present in the gas stream. Adsorption of these on the particle surface is favored at lower temperatures and provides a conductive path on the particle surface. 

When there is a heat of reaction, the temperature increases due to the reaction. In that case you have to also solve an energy balance on the catalyst pellet. A typical energy balance is... 

The possible occurrence of homogeneous reactions was tested by performing experiments in the absence of catalyst under the same reaction conditions of the catalytic tests. No ethane conversion was observed up to 700°C. In the activity tests the oxygen conversion was kept always <100% and the temperature increase, due to the exothermal reactions, was neghgible. AU the catalysts produce C2H4, CO and CO2. 

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