External heating or cooling

Fig. 2. Multipurpose fluidized bed where 1 represents the sheU 2, soHd particles 3, the blower 4, the gas distributor 5, the heat exchanger for fluidizing gas 6, internal heating or cooling 7, external heating or cooling 8, cyclones 9, the soHds feeder 10, soHds offtake 11, Hquid feed 12, the freeboard 13, the...

The mathematical model is based on the superstructure shown in Fig. 11.2. The heat transfer fluid in heat storage remains in the storage vessel during heat transfer with only the process fluid pumped around. The superstructure also shows that each unit is capable of receiving external heating or cooling in addition to direct and indirect heat integration. 

Cjhj, and the net flux F = q 2S[ cjfhj Tf) - Cjhj(T). As for the generation of enthalpy, it is represented only by the external heating or cooling. One does not put in a term for the rate of generation of heat by reaction that falls out naturally from the rearrangement of the enthalpy. Let G = Q(T) then... 

Thermal transmission methods are relatively new techniques for adhesive inspection. Heat flow is determined by monitoring the surface temperature of a test piece a short time immediately after external heating or cooling has been applied. Subsurface anomalies alter the heat flow pattern and, thereby, affect the surface temperature. The surface temperature difference can be detected by thermometers, thermocouples, or heat-sensitive coatings. Liquid crystals applied to the joint can make voids visible if the substrate is heated. 

Fig. 35. Reaction kettle (Samesreuther). The kettle is equipped with external heating or cooling coils. The coils are mounted on copper supports (b) which conduct heat to or from the kettle. This heating system is quite different from that used in the Frederking apparatus (Fig. 34). If the kettle wears out, the heating system can be used for a new kettle. These kettles are very useful, e.g., for suffonations in which varying heating and cooling must be used (see p. 211, H acid).

We therefore consider a different reaction flow model as our basic targeting model—one that can address temperature manipulation by feed mixing as well as by external heating or cooling. The model consists of a differential sidestream reactor (DSR), shown in Fig. 6, with a sidestream concentration set to the feed concentration and a general exit flow distribution function. (As mentioned in Section II, the boundary of an AR can be defined by DSRs for higher-dimensional (> 3) problems). We term this particular structure a cross-flow reactor. By construction, this model not only allows the manipulation of reactor temperature by feed mixing, but often eliminates the need to check for PFR extensions. 

The chemical process and the external heating or cooling devices may give rise to temperature changes. The evolution of the temperature was thus computed as ... 

In this chapter, a number of simplified examples have been outlined to demonstrate how AR theory may be used to answer common reactor synthesis problems related to adiabatic systems and minimum residence time. A number of natural extensions to these discussions may be carried out that enhance the use of AR theory to nonisothermal systems. For the interested reader, two notable papers are available that extend on the ideas discussed here. Nicol et al. (1997) show how the AR for an exothermic reaction may be generated that incorporates external heating or cooling, whereas Glasser et al. (1992) extend the two-dimensional preheating examples, shown in this chapter, to involving x-T-r space. 

There are very well established natural laws, ealled the laws of thermodynamies, working behind the scenes. Along with a few other features, these laws state that objects in contact with each other, absent arty external heating or cooling, will reach a state called thermal equilibrium, in whieh their temperatures will be eqtral. Under normal kitchen conditions, half an hoirr is more than errough to reach this thermal equilibrimn, so all objects in contact with air will have identical temperatiues. Why then, do they feel so different ... 

Heat management in monoUth reactors via external heating or cooling is not as effective as in PBRs due to lack of convective heat transport in the radial direction. At this point, the material of construction of the monolithic structure affects the overall performance. Monolith reactors can be made of metals or ceramics. In case of nonadiabatic reactions, metallic monoliths are preferred due to their higher thermal conductivity which partially eliminates the lacking convective contribution. Ceramic monoliths, on the other hand, have very low thermal conductivities (e.g., 3 W/m.K for cordierite [11]) and are suitable for use in adiabatic operations. 

Whether vessel has external heating or cooling jacket or if there is an internal coil... 

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