Heat transfer from a wall to a falling film (short contact time limit (Fig. 12BA

Question

Heat transfer from a wall to a falling film (short contact time limit (Fig. 12BA). Acold liq uid film flowing down a vertical solid wall, as shown in the figure, has a considerable cooling effect on the solid surface. Estimate the rate of heat transfer from the wall to the fluid for such short contact times that the fluid temperature changes appreciably only in the immediate vicinity of the wall. (al Show that the velocity distribution in the falling film, given in $2.2, may be written as v a nal20y/8) (y/6 in which pgb /2u. Then show that in the vicinity of the wall the velocity is a linear function of ygiven by (12B4-1) Downflowing liquid film enters at uniform temperature, T T-T outer edge of filmisaty Solid surface, T-To Note that the fluid at constant temperature is in the temperature Th neighborhood of the wall, .is Fig, 12BA. Heat transfer to a film almost linear. falling down a vertical wall.

Explanation / Answer

Dear student, this is a classical case of heat transfer in falling film type arrangement.

The velocity profile when put in heat transfer equation gives the final system's equation which then needs to be simplified for the boundary conditions.

The images that you have uploaded refer to many equations which are not present in these Two pages.

I recommend you to read "introduction to heat transfer" by Frank p incropera. Or I would love to teach you the derivation of such equations on chegg tu tors if you have some time. My ID is 9514657

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