Sieder-tate term

The Sieder-Tate term has been added, and fp is the Fanning friction factor for smooth tubes in turbulent flow.)... 

Again,/y is given by Equation (6.42). The Sieder-Tate term has been added to the equation. 

The inclusion of the viscosity number, Vis = Pw/p, in the process equation for heat transfer in pipes goes back to Sieder and Tate [29]. These researchers succeded to correlate experimental data obtained in pipe flow with the term (pw/p)-0 14. In this manner, the differences between the cooling and heating process were considered, these manifesting themselves by the differences in the thickness of the boundary layers. In heating, practically no boundary layer is present as compared to cooling. The heat transfer characteristics read ... 

Due to the temperature dependence of the viscosity, cooling and heating are different in as much as, under otherwise identical stirring conditions, boundary layers are formed with different thicknesses. This fact can, according to a suggestion due to Sieder and Tate [505], be taken into consideration with a viscosity term... 

The temperature dependence of the viscosity of the liquid and thereby the boundary layer thickness upon cooling and heating is taken into consideration with the viscosity term Vis = Following the suggestion of Sieder and Tate [505], that experimental data for heat transfer in pipes upon heating and cooling correlated upon inclusion of Vis , this expression was also accepted in most research studies over heat transfer in mixing. 

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. 

The Sieder and Tate relation involving coefficient of heat transfer, mass velocity, physical properties of a fluid and inside tube diameter is shown in Figure 2-25 in terms of dimensionless groups with Reynolds number as abscissa. It will be seen from Figure 2-25 that there are three distinct zones of flow. The first is the streamline region for values of Reynolds number of 2,100 and less. The series of parallel lines is expressed by the equation shown in Figure 2-25. 

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