Energy, exergy and corrosion analysis of direct absorption solar collector employed with ultra-high stable carbon quantum dot nanofluid

Nanofluid offers remarkable thermal and optical properties favourable for direct solar absorption. The nanofluids prepared by the conventional two-step synthesis method have low colloidal stability, while that synthesized through the one-step method is costly. Hence the nanofluid synthesized using an economical one-step method has great significance. In the present study, a highly stable C-dot/water nanofluid was synthesized using an economical one-pot synthesis method. The optical characterisation, corrosion analysis and cost estimation of the nanofluid were conducted. The influence of C-dot/water nanofluid on the performance of direct absorption solar collector was analyzed. The direct absorption parabolic solar collector employed with C-dot/water nanofluid yielded a maximum thermal efficiency of 73.41% at Reynolds number of 2952, while that for water was 15.79%. Thermodynamic analysis of the system and cost estimation of the nanofluid was performed to establish its commercial suitability in various solar thermal devices. The maximum exergy destruction was found to be 924.3 W and was more or less constant at all flow rates. The main highlight of the new C-dot/water nanofluid is its significantly high colloidal stability and was found to be stable for more than six months. The corrosion rate of the new C-dot/water nanofluid was obtained as 0.094 mm/year, while that for the base fluid was 0.372 mm/ year. With superior optical performance, corrosion resistance, and low production cost, the C-dot nanofluid has the potential to be a prospective working fluid in various direct absorption solar thermal systems. (c) 2021 Published by Elsevier Ltd.

Automated summary

The study synthesized a highly stable C-dot/water nanofluid using an economical one-pot synthesis method, which showed excellent thermal efficiency and stability in direct absorption solar collectors, along with superior optical performance and corrosion resistance.