The triple tube or annular space heatexchanger is used for heat transfer applications with viscous fluids. It consists of three concentric tubes.

Product flows through the annulus between tubes 2 and 3. The media fluid flows in the other two channels. The product is therefore heated or cooled from both sides. Corrugated tubes are used
to increase heat transfer rates. The result is a highly efficient heat exchanger for difficult heat transfer applications.