Multi-walled carbon nanotube nanofluids in solar flat plate collectors for advanced heat transfer solution

Flat plate solar collector (FPSC) is extensively utilized for harness energy from renewable solar thermal energy, particularly for applications like water heating and thermal storage. Sustainable and innovative designs for solar energy collection incorporate advanced technical solutions. Enhancing of the thermal conversion efficiency of the FPSC is a critical research focus, and the choice of heat transfer fluid is crucial. This investigation presents a unique hybrid nanofluid which is prepared by an improved in situ oxidation–precipitation technique and stabilized using PEG-200 to increase dispersion and thermal characteristics. This also examines the thermal performance and stability using a suitable experimental setup under varying flow rates, heat fluxes, and ambient conditions. Outcomes demonstrate a significant enhancement in collector performance, achieving up to 84% thermal efficiency and 34% exergy efficiency because of improved thermal behavior, stability, and adaptability of the proposed novel hybrid nanofluid. Furthermore, the synthesis method of the hybrid nanofluid is optimized and these improvements provide significant potential for better solar thermal applications, creating opportunities for more effective and stable renewable energy systems in the near future.