The invention relates to a mixer-heat exchanger insert or mixer-heat exchanger, having a geometry that leads to less fouling of a fluid to be temperature-controlled, wherein the mixer-heat exchanger insert has an extent in a longitudinal extension direction (L), comprising a temperature-control fluid inlet (110) and a temperature-control fluid outlet (120) and a volume (130) for guiding a temperature-control fluid, which volume extends between the temperature-control fluid inlet (110) and the temperature-control fluid outlet (120), and the mixer-heat exchanger insert has a first tubular section (10), and wherein the tubular section (10) extends in the longitudinal extension direction, wherein the tubular section is led in loops (10a, 10b, ...) transversely to the longitudinal extension direction (L).