Abstract
The solar absorption efficiency of water as a base-fluid can be significantly improved by suspending nanoparticles of various materials in it. This experimental work presents the photo thermal performance of water-based nano-fluids of graphene oxide (GO), zinc oxide (ZnO), copper oxide (CuO), and their hybrids under natural solar flux for the first time. Nanofluid samples were prepared by the two-step method and the photothermal performance of these nanofluid samples was conducted under natural solar flux in a particle concentration range from 0.0004 wt % to 0.0012 wt %. The photothermal efficiency of water-based 0.0012 wt % GO nanofluid was 46.6% greater than that of the other nanofluids used. This increased photothermal performance of GO nanofluid was associated with its good stability, high absorptivity, and high thermal conductivity. Thus, pure graphene oxide (GO) based nanofluid is a potential candidate for direct absorption solar collection to be used in different solar thermal energy conversion applications.
Highlights
Solar energy is the most abundant renewable source, and can be used for space heating [1], electricity generation, desalination, and many other similar applications [2]
Many studies on different types of nanoparticles for solar energy state state The thatcollection a comparison for photothermal performance characteristics of varioustechnique nanofluids the of direct solar absorption-based nanofluids is an encouraging foratsolar that a comparison for photothermal performance characteristics of various nanofluids at the same same conditions is much needed
Experimental outcomes absorption, changes in fluid volume temperature, and reduction in the mass of the nanofluids are describe that all nanofluids and their composites have higher solar energy absorption, higher disclosed in the perspective of their photothermal conversion efficiencies
Summary
Solar energy is the most abundant renewable source, and can be used for space heating [1], electricity generation, desalination, and many other similar applications [2]. The conventional surface-based solar collector cannot be used at high temperatures because of the heat losses [9] To decrease these heat losses, a volumetric type of solar collector was suggested, which uses nanoparticle suspension as the absorbing medium [10,11]. In volumetric solar collectors, working fluid absorbs solar radiation directly from sun [12] This type of solar collector has certain advantages over the surface-based type of solar collectors including minor heat losses, lower thermal resistance, radiation trapping, and increased thermal conductivity [13]. All this helps in enhancing the overall performance of the solar collector [14]. The solar absorption efficiency is improved by suspending nanoparticles of various materials in heat transfer fluid [17]
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