[DMV]

Hello! Faced with a problem of this nature. A sediment accumulates in the heat exchanger, clogs all the channels, pink / purple color from which the device stops working .. The heat exchanger capacity is made of aluminum, ethylene glycol diluted with distilled water is run through this capacity. Max. solution temperature 50 ° C. Who knows how to prevent the appearance of sediment? Thank!

[Enthalpy]

Do I see that the sediment consists of thin sheets?

This would suggest exfoliating corrosion. Some aluminium alloys are prone to it, Al-Zn more so, and water at +50°C is already aggressive to many alloys. Welds make the situation worse, especially when the full thermal treatment isn't made again after welding, that is almost always. Other base metals, like iron, are less prone to it.

If possible, a chemical analysis of the sediment would tell more, better if it includes the minor constituents of the flakes: for instance Al with 5%Zn or 4%Cu would tell "inadequate alloy". Or could you inspect the whole circuit and see where material is missing? It may be tubing elsewhere, not necessarily at the heat exchanger.

Once you identify the location of missing material, the best solution would be to replace it with a better alloy if manageable. Additives exist as "corrosion inhibitors" for water+glycol, but if an aluminium alloys is poorly chosen they won't make a miracle. Contractors can deposit a protective layer like Ni in the tubes; as long as the layer lasts the tubes are protected, afterwards the corrosion may accelerate (or not) due to the resulting electric cell.

[DMV]

Thank you so much! Yes, there are thin sheets! But there are fewer of them than purple crystals .. Why did I turn to the forum? I think it's me doing something wrong)! Now I am looking for a heat exchanger made of copper or stainless steel. Although the aluminum heat exchanger completely coped with the task of maintaining a stable temperature and was also optimal in size ..

[Enthalpy]

I'm not sure the sediments result from aluminium oxidation. I know that many aluminium alloys can't cope with warm water. With a well-chosen alloy, possibly anodized or covered with a different metal, and inhibitors in the liquid, aluminium has good chances.