Exploring the performance of a novel solar water heater by combining three augmentation approaches (nanofluids, absorber roughness, and surface coating)

Abstract

Three unique approaches were adopted in this research first for the solar water heater (SWH), a surface-modified (resurfacing) absorber plate was manufactured through the steel shot-blasting approach. Furthermore, the naturally acquired activated carbon nanomaterials (ACNMs) have been synthesized and the same was employed as nanofluids (NFDs) and coating material on the absorber plate through the spray painting. Also, ACNMs and water, (DIW) based nanofluids were synthesized using the double-step methodology and applied as heat transfer medium (HTM). In addition, the thermal properties of DIW-ACNM such as ratios of thermal conductivity (TC), specific heat, viscosity, and density were measured experimentally and colloidal stability of NFDs was also ensured through zeta potential and SEM analysis. The temperature difference of the HTM across the SWH was recorded as 7.5, 9.8, 10.6, and 12.04 °C at 0, 0.1, 0.25, and 0.4 vol % of ACNMs loading respectively. The thermal efficiency of modified SWH was increased up to 52.7% with a volume fraction of 0.4% despite a proliferation in pressure drop and pumping power by 23.5 and 22.1% respectively. Overall, combining ACNM as an NFD and coating material along with shot-blasting on the absorber plate had excellent improvement in the SWH performance with a performance augmentation factor of 1.14.