Optimization of silver nanoparticle-enhanced nanofluids for improved thermal management in solar thermal collectors

Abstract

This study aimed to enhance the thermal performance of solar thermal collectors using silver nanoparticle-enhanced nanofluids. Silver nanoparticles, known for their high thermal conductivity, were synthesized via chemical reduction, stabilized with polyvinylpyrrolidone, and dispersed in base fluids like deionized water and ethylene glycol. Various nanoparticle sizes (20 nm to 50 nm) and concentrations (0.2 wt% to 0.8 wt%) were tested to optimize thermal conductivity while maintaining stability. Thermal properties were measured using the transient hot-wire method for conductivity, rotational rheometer for viscosity, and differential scanning calorimetry for specific heat capacity. Stability was monitored via UV-Vis spectrophotometry. Results indicated that smaller nanoparticles (20 nm) at lower concentrations (0.2 wt%) yielded the highest thermal conductivity of 0.73 W/mK, due to their high surface area-to-volume ratio. Viscosity increased with nanoparticle size and concentration, peaking at 0.0012 Pa.s for 50 nm nanoparticles at 0.8 wt%. Specific heat capacity remained relatively stable, slightly increasing with larger nanoparticles. Conclusions reveal that optimizing nanoparticle size and concentration is crucial for balancing enhanced thermal conductivity and manageable viscosity. These findings underscore the potential of silver nanoparticle-enhanced nanofluids in improving the efficiency of solar thermal systems, offering valuable insights for future research in sustainable energy technologies.

Keywords:
Silver nanoparticles; Nanofluids; Thermal conductivity; Thermal management systems