Dynamic Scraped Surface Heat Exchanger

Dynamic scraped surface heat exchanger was created to rectify the problems that were found in other kinds of heat exchangers. They augment heat transfer by several ways such as removing the fouling layers, increasing turbulence in case of high viscosity flow and avoiding the generation of ice and other process by products.

The dynamic scraped surface heat exchanger inculcates particular internal mechanism that once in a while removes the product from the heat transfer wall. Notable technologies for indirect heat transfer employ tubes or flat surfaces. Their aim is to barter larger amount of heat unit region by generating as much turbulence as possible below given pumping power limits. Typical approaches to accomplish this comprise of corrugating the tubes or plates or extending their surface with fins.

The Application and Concept

Nevertheless, these geometry conformation technologies, the calculation of optimum mass flows and other turbulence pertaining factors become diminished when fouling comes, obliging designers to fit significantly larger heat transfer regions. There are many types of fouling comprising particulate accumulation, precipitation, sedimentation and generation of ice layers. Viscosity is yet another factor which is a threat to heat transfer. Elevated viscous fluids seem to generate deep laminar flow a condition with very poor heat transfer rates and high pressure losses containing a considerable pumping power frequently exceeding the exchanger design limits.

The Various Kinds of Dynamic Scraped Surface Heat Exchangers

The product side is scarped by blades attached to a moving shaft frame. These blades are made of a rigid plastic material to avoid damage to the scraped surface. There four major types of dynamic scraped surface heat exchangers all depending on the arrangements of the blades. Rotating, tubular dynamic scraped surface heat exchangers in which the shaft is placed parallel to the tube axis, not necessarily coincident and spins at different frequencies from appropriately dozen to  more than 100rpm. The amount of blades oscillate between 1 and 4, may take advantage of centrifugal forces to scrape the inner surface of the tube.

Reciprocating, tubular ones: where the shaft is concentric to the tube and moves longitudinally without rotating. The frequency spans between 10 and 60 strokes per minute. The blades may differ in number and shape from baffle-like arrangements to perforated disk configurations. And rotating, plate: the blades wipe outside surface of circular plates arranged in sequence within a shell. The heating or cooling fluid moves inside the plates. The frequency is about several dozen rpm.

Questions:

• What is dynamic scraped surface heat exchanger?
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