Abstract
For solar thermal harvesting, an experimental study was performed on the thermal absorption performance of water-based carbon nanotubes (CNTs), Cu, and Al2O3 nanofluids using a halogen lamp-based thermal radiation system. The effect of nanoparticle concentrations (0.01 wt.%, 0.1 wt.%, and 1 wt.%) on the nanofluid dispersion, stability, and thermal absorption characteristics was investigated, and a comparative analysis was performed for each type of nanofluid. All types of nanofluids increased the absorbance and electrical conductivity with increasing nanoparticle concentration, which contributed to improving the thermal absorption performance of nanofluids. The results showed that the thermal absorption performance was high in the order of carbon-based nanofluids (CNTs), metal-based nanofluids (Cu), and oxide-based nanofluids (Al2O3). In CNTs nanofluids, the thermal absorption performance expressed the time reduction rate, which was 12.8%, 16.3%, and 16.4% at 0.01 wt.%, 0.1 wt.%, and 1 wt.% test cases, respectively. Therefore, the 0.1 wt.%-CNTs nanofluid is more economical and appropriate. However, in Al2O3 nanofluids, the time reduction rate of the 1 wt.% nanofluid was significantly higher than that of the 0.01 wt.% and 0.1 wt.% nanofluids. In Cu nanofluids, unlike CNTs and Al2O3 nanofluids, the time reduction rate constantly increased as the nanoparticle concentration increased.
Highlights
Owing to the continuously increasing energy consumption and undesirable consequences of environmental pollution, researchers need to develop environmentally friendly, clean, and sustainable energy resources, such as solar, wind, and geothermal energy
distilled water (DW) was used as the base fluid to manufacture three different types of nanofluids
We indicate that the zeta potential or electrical conductivity (EC) measurements are needed in terms of the stability and dispersion of nanofluids
Summary
Owing to the continuously increasing energy consumption and undesirable consequences of environmental pollution, researchers need to develop environmentally friendly, clean, and sustainable energy resources, such as solar, wind, and geothermal energy. Research on the effects of flow mixing and nanomaterial on heat transfer enhancement in solar collector systems has been published [9,10,11] Various nanoparticles such as carbon-(CNTs and graphene), metal-(Ag, Au, and Cu), and oxide-based (Al2O3, CuO, SiO2, TiO2, and ZnO) nanoparticles are mixed with the working fluid (water, alcohol, oil, etc.) to manufacture nanofluids. Lee et al [24] investigated the effect of nanoparticle concentration (0.1 wt.%, 0.3 wt.%, and 0.5 wt.%) on the solar thermal absorption performance of Al2O3/water nanofluids in an actual environment They concluded that the temperature increases for the 0.1 wt.%, 0.3 wt.%, and 0.5 wt.% alumina nanofluids were 3.1%, 12.5%, and 13.9% higher, respectively, than distilled water (DW). The thermal absorption performance was compared and analyzed with the time reduction rate by measuring the time required for each nanofluid to reach the same temperature (20–50 ◦C)
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