Experimental analysis of hydroxyapatite nanofluid for enhanced thermal performance in solar evacuated tube collectors

Sustainable Development Goals motivated this investigation for effective energy harvesting. Thermal performance enhancement helps sustainable energy practices by minimizing fossil fuel use while establishing cleaner energy technologies. The study uses hydroxyapatite and deionized water as working fluids with the mass flow rate of 0.5–1.5 lit/min to experimentally examine the thermal performance of heat pipe-based solar evacuated tube collectors. Samples of hydroxyapatite nanofluid with varying volume fraction as 0.05 %, 0.1 %, and 0.15 % have been used in deionized water. The structure of hydroxyapatite has been examined using a scanning electron microscope, and its structural characteristics were ascertained using X-ray diffraction. The Zeta potential measurement was performed to assess the permanency of the working fluid samples and revealed that the generated samples were stable for as long as 30 days. It was investigated and discussed how changing concentrations of the nanofluid affected its thermophysical characteristics. An impact mass flow rate and volumetric concentrations for nanofluid were considered when examining the thermal performance of SETC. In contrast with water, the thermal performance has been achieved at higher in SETC as 38.5 % at the volume fraction as 0.15 % at the mass flow rate as 1.5 lit/min. The results indicate that employing nanofluid samples significantly increases the temperature differential and energy gain. Based on research outcomes, these proposed findings are suitable for industrial and household applications.