Heat transfer consideration

This expression insures that the heat-transfer considerations of the second law of thermodynamics are satisfied. For a given pair of corresponding temperatures (T, t) it is thermodynamically and practically feasible to transfer heat from any hot stream whose temperature is greater than or equal to T to any cold stream whose temperature is less than or equal to t. It is worth noting the analogy between Eqs. (9.2) and (3.5). Thermal equilibrium is a special case of mass-exchange equilibrium with T,t and AT " corresponding to yi,Xj and ej, respectively, while the values of rrij and bj arc one and zero, respectively. 

As we noted earlier, there may be heat transfer considerations or other factors that dictate the use of a CSTR even when the yield considerations are unfavorable. In such cases the yield... 

This problem indicates the considerations that enter into the design of a tubular reactor for an endothermic reaction. The necessity of supplying thermal energy to the reactor contents at an elevated temperature implies that the heat transfer considerations will be particularly important in determining the longitudinal temperature profile of the reacting fluid. This problem is based on an article by Fair and Rase (1). 

The distillation residue contains mainly glycerol however, condensation and polymerization reactions also took place indicated by coloration of the liquid. These reactions might increase viscosity and decrease heat transfer considerably. 

This involves solution of equation 18.4-6 together with equations 18.4-2 and -3. A stepwise algorithm is as follows, with indicated as the highest allowable value of T for whatever reason (heat transfer considerations, product stability, etc.) ... 

Thus the initial growth is largely controlled by inertial restraints and the radius increases linearly with time [Eq. (12)], whereas at long times heat transfer considerations become predominant and the growth is given by Eq. (16). The actual variation of r with t is less than either of these two asymptotic extremes (see Theofanous, 1969). 

Several factors need to be kept in mind concerning x-ray resist design. Firstly, source design has mainly utilized electron bombardment of the target material to generate x-rays. Power output is limited by heat transfer considerations, and when account is also taken of the separation between source and exposure plane (wafer) as necessitated by geometrical considerations, it... 

In industrial practice, the laboratory equipment used in chemical synthesis can influence reaction selection. As issues relating to kinetics, mass transfer, heat transfer, and thermodynamics are addressed, reactor design evolves to commercially viable equipment. Often, more than one type of reactor may be suitable for a given reaction. For example, in the partial oxidation of butane to maleic anhydride over a vanadium pyrophosphate catalyst, heat-transfer considerations dictate reactor selection and choices may include fluidized beds or multitubular reactors. Both types of reactors have been commercialized. Often, experience with a particular type of reactor within the organization can play an important part in selection. 

For heat transfer considerations, the local heat transfer coefficient and the local Nusselt number are written in the usual way as... 

Heat Transfer Considerations. From a qualitative point of view the observed effect appears explicable in terms of a slow cooling of the solid. However, when examined more closely, the actual heat transfer can account for only a very small part of the observed delay. Three questions may be raised concerning the cooling of the sample ... 

Cost data for the purchase and installation of the insulation are available, and the length of service life can be estimated. Therefore, a relationship giving the effect of insulation thickness on fixed charges can be developed. Similarly, a relationship showing the cost of heat lost as a function of insulation thickness can be obtained from data on the value of steam, properties of the insulation, and heat-transfer considerations. All other costs, such as maintenance and plant expenses, can be assumed to be independent of the insulation thickness. 

Explosive Initiation Evaluation. A model described by Evans, is derived based on heat-transfer considerations. It i ndicates... 

Heat transfer considerations play a crucial role in the design and operation of many modern devices. New approaches and methods of analyses have been developed to understand and modulated (enhance or suppress) such energy interactions. Modulation typically occurs through actively controlling the surface phenomena, or focusing of the volumetric energy. In this section we discuss one such example microscale heat transfer. 

The optimization of an electrochemical reactor calls for a full description of the process to accomplish the specific objective of the mass and the energy balances together with heat transfer considerations and thermodynamic and enthalpy changes that are related to the unit cell and the whole stack [1,2]. A full description of the kinetics of both processes, the electric properties of the cell components, and the hydrodynamic aspects of the entire cell is also required. 

The lining options for vessels have been described in Ch. 4 and reproduced here to aid our discussion. The selection of lining technology depends on several factors such as chemical resistance, material availability, vessel size, heat transfer consideration, shop versus field application, and cost (Tables... 

Note that the correlation was established for a tape with no heat transfer considerable increases in heat transfer are predicted with tapes that act as effective fins [193], The correlation does not seem to be applicable to heating or cooling with a constant wall temperature [114], but more recently a correlation has been proposed for that boundary condition [378] ... 

As we noted earlier, there may be temperature con-trol/heat transfer considerations or other factors that dictate the use of a CSTR even when the yield considerations are unfavorable. In such cases the yield of the desired product may be significantly increased by using a battery of CSTRs in series. If desired, one has the additional flexibility granted by using tanks with different volumes or tanks... 

GEOMETRICAL HEAT TRANSFER CONSIDERATIONS FOR A STACK OF ROUND CONDUCTORS... 

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