As a result of attendant drag forces that are associated with flowing viscous liquids, viscous sublayers tend to be thick. In other instances, turbulent conditions within the core liquid are no longer attained without significant pressure loss. To overcome this problem and reduce high pumping costs, you must physically remove the layer of fluid on top of the heat transfer surface. After, it would help if you mixed them with bulk fluids inside the heat exchanger. Because the fluid is heated, the heat gets directly conveyed from walls to bulk liquid. This process is popular with heat-sensitive liquids (pharmaceutical and food products).
A scraped surface heat exchanger contains a spring-loaded blade that rotates and scrapes the surface while also effectively removing liquid from it. The blades do move against the heat transfer surface because of rotational forces. As the liquid is being removed, the system also removes fouling substances that have deposited on the surface. The process ensures that contamination of the fluids is significantly reduced. This process is incredibly essential when texture and taste are crucial qualities of the products being produced.
Scraped Surface Heat Exchangers
A wiped surface heat exchanger is like a scraped surface heat exchanger except of one significant difference. A wiped surface exchanger passes over the surface within proximity (never touching). This method is preferable when a surface does not tolerate a blade or because of adverse contamination effects.