Expert ForumsHeat Transfer

Topic: Re: Fluid handling with conventional heat exchangers

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Assuming that the definition of fibrous fluids means a slurry of fibrous particles, there can be a number of ways to approach the problem.
First, one must understand the slurry, as the viscosity is an important parameter in determining the heat transfer rate. Once this is understood along with the minimum transport velocity of the solid, an approach to designing an exchanger may be pursued. If the fiber length is greater than 3 mm, it will preclude the use of a plate- and frame-style unit. The use of a shell and tube or spiral plate heat exchanger may be possible, provided the minimum transport velocity is maintained at all points in the unit.
Maintaining this velocity can sometimes be difficult in the heads of a shell and tube unit and often results in the choice of a spiral plate design. The single flow-path design of a spiral plate exchanger results in a constant velocity and shear rate throughout the unit without the need for distribution headers or tube sheets such as are encountered in plate and shell and tube designs. Any tendency to foul or plug results is an increase in velocity, and therefore shear-rate, in the channel which can help to clear out the fouling material.