Abstract:
Flat plate solar collectors (FPSC) should meet durability requirements which are related to the equipment ability to resist aging and damage occurring during lifetime. To face durability issues, especially concerning to freezing and corrosion resistance, Brazilian flat plate solar thermal collector manufactures are embracing product lines with stainless-steel (SS) tubes. Without wishing to proof if the use of SS tubes is beneficial to FPSC freezing and corrosion resistance, the objective of this work is restricted to analyze to what extent SS tubes are being used in Brazilian solar thermal market and its implications on solar collector thermal efficiency, considering that copper (Cu) tubes are the conventional material employed as FPSC tubes. For this purpose, a survey involving national manufacturers was carried out. Results revealed that 57% of the manufacturers belonging to the mandatory Brazilian Solar Thermal Labelling Program have at least one product line made of SS. Additionally, since SS has lower thermal conductivity than copper, an experimental study was conducted to identify the impact of Cu replacement by SS on FPSC thermal efficiency. Results showed that absolute and relative maximum reduction on efficiency is, respectively, around 2% and 7% at most, which is small when compared to the Cu to SS thermal conductivity difference, which is around 95% less for SS. This indicates that if freezing and corrosion resistance is confirmed, therefore, the use of SS tubes may be a good solution for solar thermal collectors installed in cold regions and/or subject to aggressive ambient/water conditions.
Referência:
ARA, Paulo José Schiavon; SOWMY, Daniel Setrak. Use of stainless-steel tubes to replace the usual copper tubes in flat plate solar collectors in the Brazilian solar termal market: overview and impact on energy efficiency. In: ISES SOLAR WORLD CONGRESS, 2025, Fortaleza. Proceedings… 9 p.
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