Solar fluid

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Solar fluid in the canister

As solar liquid ( English collector fluid ) which is in solar panels flowing liquid mentioned. It transfers the heat from the collectors to the place of use.

It must be able to withstand high temperatures and at the same time remain liquid at freezing temperatures. The liquid must withstand the high stagnation temperatures and must not freeze in winter. A mixture of propylene glycol and water has prevailed, with a mixing ratio of around 50 percent glycol. Other suitable forest protection is: Di-propylene glycol or 1,3-propanediol. In some cases an anti-corrosion agent is also included. Similar mixtures are also used for engine cooling in vehicles. This fluid has to be replaced after years due to aging. If a system has found itself in extreme or particularly frequent stagnation states, it may be necessary to replace the fluid earlier. In the event of stagnation, temperatures of 200 to 260 ° C occur and the glycol decomposes thermally. It can then lead to the so-called cracking of the glycol, which can lead to lumpy residues. Therefore, a collector system should be designed in such a way that if it overheats it is emptied by the formation of steam and the high temperatures act on the solar fluid for as short a time as possible. For this purpose it has a buffer volume and a corresponding arrangement of the collector piping.

Liquids such as thermal oil or brine have not caught on. Oil has a lower heat capacity and is more difficult to handle. Brine is corrosive.

literature

  • Peuser, Remmers, Schnauss: Long-term experience of solar thermal energy , Solarpraxis, Berlin 2001, ISBN 3-934595-07-3 , pp. 218–225
  • Chapter 3.2.2: Solar fluid. In: T. Schabbach , P. Leibbrandt: Solarthermie: How the sun becomes heat , Springer-Vieweg, Berlin / Heidelberg 2014, ISBN 978-3-642-53906-0 , pp. 48–49
  • Heat transfer fluids. In: Sonne Wind & Wärme No. 7–8 / 2017, pp. 30–33; with a market overview of solar fluids
  • Wolfgang Böhmer: Heat transfer fluids have to withstand high requirements. In: Building & Automation No. 4/2018, pp. 66–69

Individual evidence

  1. ↑ Goran Mijic: Solar Energy and Technology , Volume 2, De Gruyter, 2018, ISBN 978-3-11-047577-7 , p. 104
  2. ↑ Peuser, Remmers, Schnauss: long-term experience of solar thermal energy , Solarpraxis, Berlin 2001, ISBN 3-934595-07-3 , p. 218
  3. ↑ a b Info sheet No. 34 (March 2011) , Bundesindustrieverband Deutschland Haus-, Energie- und Umwelttechnik eV, accessed on October 22, 2017