Optimization of silver/water-based porous wavy direct absorption solar collector

Abstract

Direct Absorption Solar Collectors (DASCs) are a widely utilized technology in residential applications. However, having known the limitation in DASC size, the efficiency must be enhanced by applying effective modifications and optimizing design parameters. In this study, the performance of a wavy bottom-shaped collector filled with an aluminum porous medium was investigated and the most influential characteristic parameters are specified. Then a design for DASC using Polyvinylpyrrolidone-coated silver nanofluid is proposed and characteristic parameters are optimized based on the full factorial design of the experiment methodology. The model consists of four primary factors, including nanofluid volume concentration (C=0.025%,0.05%,0.1%), porosity (ε=0.8,0.88,0.95), bottom wave amplitude (A=2.5,5,7.5mm), and bottom wavenumber (λ=15,30,60m−1). The results indicated that lowering porosity and increasing nanofluid concentrations improves collector efficiency, whereas rising the wave amplitude and wavenumber causes a higher pressure drop. Additionally, by employing the full factorial design, the main and interaction effects of factors on the efficiency and pressure drop of DASC as the response variables are evaluated. Thus, an optimum value is observed for wave amplitude to reach maximum efficiency and minimize pressure drop. By integrating a porous medium and a wavy bottom with nanofluid, the efficiency of DASC is enhanced from 52 to 93.7%, paving the way for their use in residential applications.