Hybrid Nanofluid in a Direct Absorption Solar Collector: Magnetite vs. Carbon Nanotubes Compete for Thermal Performance

The paper presents the experimental measurements of thermal efficiency of a tubular direct absorption solar collector (DASC) with a hybrid nanofluid based on magnetite (Fe3O4) and multi-walled carbon nanotubes (MWCNT). The volumetric concentration of Fe3O4 and MWCNT was 0.0053% and 0.0045%, respecti...

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Bibliographic Details
Main Authors: Struchalin, Pavel, Kuzmenkov, Dmitrii M, Yunin, Vladimir S, Wang, Xinzhi, He, Yurong, Balakin, Boris
Format: Article
Language:English
Online Access:Request full text
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Summary:The paper presents the experimental measurements of thermal efficiency of a tubular direct absorption solar collector (DASC) with a hybrid nanofluid based on magnetite (Fe3O4) and multi-walled carbon nanotubes (MWCNT). The volumetric concentration of Fe3O4 and MWCNT was 0.0053% and 0.0045%, respectively. The experiments were carried out for the flow rates of 2–10 L/min and a temperature difference up to 20 ∘C between the environment and the DASC. The performance of the DASC with a hybrid nanofluid was in the range of 52.3–69.4%, which was just beyond the performance of the collector with surface absorption. It was also found that using a MWCNT-based nanofluid with an equivalent total volumetric concentration of particles (0.0091%), the efficiency was 8.3–31.5% higher than for the cases with the hybrid nanofluid. Keywords: direct absorption solar collector; hybrid nanofluid; carbon nanotubes; magnetic nanofluid; iron oxide