At the beginning of August the Swiss company Clariant brought a new heat transfer medium for solar thermal systems out onto the market under the name Antifrogen Sol HT. The antifreeze has been designed to survive stagnation temperatures of over 270 °C unscathed.
First the technical background: The heat transfer fluid is the wear and tear element of a solar thermal system. The mixture of water, glycol as antifreeze and inhibitors to reduce the corrosiveness of the heat transfer medium, has to be checked regularly and replaced if necessary. For if the collector overheats in the summer because the tank is already full, but the sun is still shining brightly, the water and glycol evaporate. Under these conditions the inhibitors crystallise out on the hot copper surface and undergo thermal decomposition there. The result: narrowed, and in extreme cases, blocked pipes and a reduced corrosion protection.
Clariant has now replaced the normal propylene glycol with glycols from company-internal production sites that have a higher boiling point. This antifreeze has a boiling point of over 270 °C at 1 bar and should make sure that the inhibitors stay liquid even if the system stagnates. Antifrogen Sol HT was developed by Clariant Germany and is also produced there in-house.
www.antifrogen.de (availability via sales partner)