Heat transfer medium flows through the tubes. The tube elements generate radial mixing in the product flow and at the same time transfer heat to the product through their large surface area. Due to the narrow residence time distribution and low axial back mixing, there are no stagnant zones in the SMR® heat exchanger. This ensures that the temperature of the polymer melt can be accurately controlled. Low shear forces and pressure drop are other considerable advantages of the SMR® cooler which can not only be installed vertically but also horizontally. More than 200 SMR® units were sold to the fiber industry and are still in operation.