Heat transfer correlations

The Nusselt-type expression was used by Handley and Heggs (1968) to correlate heat transfer coefficients between particulate solids and fluid as ... 

Rohsenow, W. H., A Method of Correlating Heat Transfer Data for Surface Boiling of Liquids, Heat Transfer Div. ASME, Atlantic City, NJ. Meeting Nov. 25, (1951) Paper No. 51-A-llO. 

Rousenow. W.M. Trans. Am. Soc. Mech. Ping. 74 (1952) 969. A method of correlating heat transfer data for surface boiling of liquids. 

It is often convenient to correlate heat-transfer data in terms of a heat transfer factor, which is similar to the friction factor used for pressure drop (see Volume 1, Chapters 3 and 9). The heat-transfer factor is defined by ... 

An analogy exists between the transfers of heat and mass in moving fluids, such that correlations of heat transfer involving the Prandtl number are valid for mass transfer when the Prandtl number Cp/k is replaced by the Schmidt number p pkd. This is of particular value in correlating heat transfer from small particles to fluids where particle temperatures are hard to measure but measurement of mass transfer may be feasible, for example, in vaporization of naphthalene. 

Although general treatments of the flow in fluidized beds of coarse particles, in view of the difficulty of the problem, will only evolve slowly, there have been some promising developments. These include the success achieved in correlating heat transfer data (7, 113., 114) and the development of scaling parameters that permit the use of cold flow models to study many of the characteristics of AFBC s (114%115). 

The results of the more extensive experimental investigations are outlined in Table VI. Except for scattered early data (P6, R2), the work of Chilton et al. (C5) was the first study to use the conventional groups for correlating heat transfer to jackets or coils. In some cases the temperatures at different points in the liquid varied by as much as 5°F. They used a variety of liquids, and found values of h in the range of 20-2000 B.T.U./(hr.) (ft.2) (°F.), depending on the conditions used. 

Numerous measurements of heat transfer between the fluid bed and immersed surface have been carried out these have been reviewed by Kunii and Levenspiel (K24), Davidson and Harrison (D5), Botterill (B12), and Zabrodsky et al. (Zl, Z2). Wen and Leva (W3) and Wender and Cooper (W5) correlated heat-transfer data at the walls of fluidized beds. However, the data utilized for their correlation were obtained with a... 

It should be remembered, that Sieder and Tate [505] used the viscosity term to correlate heat transfer for cooling and heating, which makes little sense. In each case the boundary layer is completely different also with identical fluids. With the viscosity term the effect of the different /z(T) behavior of the fluid should be separately taken into account for either heat transfer direction, see Section 7.4. 

Nusselt number Nu = hDIk Used with Re and Pr to correlate heat-transfer data... 

In stratified flow, the stratified layer at the lower part of the tube free-flow area is influenced primarily by shear effects, while a thin film covers the upper portions of the inner tube wall and stratifies under the influence of gravity. The heat transfer conditions in two regions are quite different, but it is a standard practice to correlate heat transfer based on the entire perimeter. In Table 17.25, a correlation based on the modified Nusselt theory is given for stratified flow, developed by Chato [87] and modified by Jaster and Kosky, as reported by Carey [76]. Consult Carey [76] and Butterworth [81] for a detailed analysis of related phenomena. The most recent condensation correlations are given by Dobson and Chato [89]. 

Keywords Dufour effect Evaporation Frossling correlation Heat transfer Fatent heat Mass transfer Nusselt number Ranz-Marshall correlation Soret effect Stefan flow... 

A heat exchanger with iV transfer units allows a temperature change in a fluid equal to N times the average temperature difference. It should be noted that the number of transfer units based on the over-all temperature difference is always less than or at most equal to the number of transfer units based on the film difference. In correlating heat transfer data it is important to define clearly the type of transfer unit which is used. 

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