ABSTRACT
Many designs of scraped surface heat exchangers (SSHE)
exist. Common to them all, however, is that a SSHE con-
sists of two coaxial cylinders with an internal rotating shaft
fitted with blades at an angle b to the shaft, shown in cross section in Fig. 1. Fluid flows axially along the SSHE
between the static and rotating cylinders. The blades
improve the heat transfer between the heating or cooling
medium by scraping the inner tube wall and, therefore,
preventing fouling, burn-on, or freeze-on problems. This
is achieved through a combined effect of turbulence, inter-
facial film removal, and mixing of the product. High heat
transfer coefficients can be achieved as the boundary layer
is continuously replaced by fresh material. As the product
remains in contact with the heat transfer surface only for a
few seconds, smaller heating areas are needed than for
conventional heat transfer equipment and higher tempera-
ture driving forces between the cooling or heating medium
and the product can be used.
