Kern’s method

Example 10-21. Vertical Thermosiphon ReboUer, Kern s Method ... 

Further detailed discussion of Kern s method together with a worked example is presented in Volume 6. 

Though Kern s method does not take account of the bypass and leakage streams, it is simple to apply and is accurate enough for preliminary design calculations, and for designs where uncertainty in other design parameters is such that the use of more elaborate methods is not justified. Kern s method is given in Section 12.9.3 and is illustrated in Examples 12.1 and 12.3. 

Only the thermal design will be considered. This example illustrates Kern s method. Coolant is corrosive, so assign to tube-side. 

This approach will give more satisfactory predictions of the heat-transfer coefficient and pressure drop than Kern s method and, as it takes into account the effects of leakage and bypassing, can be used to investigate the effects of constructional tolerances and the use of sealing strips. The procedure in a simplified and modified form to that given by Bell (1963), is outlined below. 

Appreciably lower than that predicted by Kern s method. This shows the unsatisfactory nature of the methods available for predicting the shell-side pressure drop. 

Using Kern s method, the mean coefficient for a tube bundle is given by ... 

Pressure Drop on the Shell Side with 25% Open Segmental Baffles by Kern s Method 194... 

The calculation procedure shown is based on Kern s method,1 with modifications to include the heat transfer correlations presented earlier... 

Pressure Drop ou the Shell Side with 25% Opeu Segmental Baffles, hy Kern s Method (1950, p. 147)... 

Gs = mass flow rate per unit area, based on the total flow and free area at the bundle equator. This is the same as calculated for Kern s method do = tube outside diameter. 

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