Modeling contact heating

Contact Drying. Contact drying occurs when wet material contacts a warm surface in an indirect-heat dryer (15—18). A sphere resting on a flat heated surface is a simple model. The heat-transfer mechanisms across the gap between the surface and the sphere are conduction and radiation. Conduction heat transfer is calculated, approximately, by recognizing that the effective conductivity of a gas approaches 0, as the gap width approaches 0. The gas is no longer a continuum and the rarified gas effect is accounted for in a formula that also defines the conduction heat-transfer coefficient ... 

Direct contact heat transfer, 185 Dispersion model, 560-562 first order reactions, 561 second order reactions, 562 Distillation, 371-457 batch, 390 binary, 379 column assembly, 371 flash, 375... 

The heat transfer coefficient in the batch rotative reactor has been determined both theoretically and experimentally. As indicated by the heat transfer model (Eq.1-3), the heat transfer coefficient between the reactor and the feedstock is a function of the thermophysical properties of the feedstock Cp, p and X, the contact heat transfer coefficient and the bottom layer renewal efficiency fi. When the feedstock material is known, the thermal properties and can be determined [5]. The heat transfer coefficient becomes a function of and t u. 

Our discussions on the film model for heat transfer showed an exact parallel with the corresponding mass transfer problem. The same parallel holds for unsteady-state transfer. Thus, for Fo = Xt/pC rl 0 (short contact time), the time-averaged heat transfer coefficient is given by... 

A semiempirical analysis of heat transfer to impacting sprays has been developed by considering the major components of spray heat transfer to consist of (1) contact heat transfer to impacting droplets, (2) convective heat transfer to gas, and (3) thermal radiation heat transfer [142], The model further assumes that the droplet interference is negligible (i.e., dilute sprays), and the three heat transfer components are independent of each other. The heat transfer data to a single impacting droplet have been correlated by the Weber number, surface temperature superheat, and thermophysical properties. 

Modeling the heat generation therefore requires some representation of the interface contact behavior together with the viscous dissipation behavior of the material. Simple analytical approaches are discussed in this section numerical methods, in which heat generation is calculated directly from coupled models of the temperature field and metal deformation, are discussed in section 10.3, Metal Flow. ... 

The electrolysis cell is best constructed of a refractory of high alumina content, and containing as little silica as possible, owing to the ready attack of silica by thorium metal. The small-scale cell illustrated in Fig. 7.6, however, uses a silica pot and care is taken to prevent thorium metal contacting the silica wall or base. The small, 6 kg scale, model is heated externally, although a more conventional internal heating system is necessary for a production scale cell. 

Kom GA, Korn TM (1968) Mathematical handbook. McGraw-Hill, Boston Landau LD, Lifshitz EM (1959) Fluid mechanics, 2nd edn. Pergamon, London Morijama K, Inoue A (1992) The thermodynamic characteristics of two-phase flow in extremely narrow channels (the frictional pressure drop and heat transfer of boiling two-phase flow, analytical model). Heat Transfer Jpn Res 21 838-856 Ngan CD, Dussan EBV (1982) On the nature of the dynamic contact angle an experimental study. JEluidMech 118 27- 0... 

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