The precipitants are inverse soluble salts and, most commonly, calcium carbonate. Precipitation
fouling usually follows a linear fouling curve.
The temperature distribution, which is dependent on the flow conditions as well as the available overall temperature difference across the heat exchanger, affects the location of the precipitation.
If the region of super-saturation is at the heat transfer surface, then precipitation likely occurs.
If the super-saturation is away from the heat transfer surface, crystals will form in the bulk fluid and deposit in the same manner as a particulate [2].
Calcium carbonate will crystallize in two forms, calcite and aragonite.