Optimisation of thermo-optical properties of SiO2/Ag–CuO nanofluid for direct absorption solar collectors

Augmenting thermal and optical properties of working fluids used in solar thermal conversion systems using hybrid nanomaterials is gaining prominence. In the present study photo-thermal analysis and thermal conductivity investigations were performed on SiO2/Ag–CuO binary water based nanofluid. The influence of particle concentration and surfactant concentration on thermo-optical properties were investigated using the design of experiment concept. Analysis of variance (ANOVA) was employed to study the significance of the process parameters on thermal conductivity and solar weighted absorption fraction of nanofluid. The statistical optimisation of the process parameters was done using the desirability function. The optimum combination of nanoparticles and surfactant that yield good thermal conductivity and solar absorption was found to be SiO2/Ag: 206.3 mg/L, CuO: 864.7 mg/L, and SDS (surfactant): 1996.2 mg/L. The optimum mass fraction of constituents yielded a relative thermal conductivity of 1.234 and solar weighted absorption fraction of 82.82%.