A facile, green fabrication of aqueous nanofluids containing hydrophilic functionalized carbon nanotubes toward improving heat transfer in a closed horizontal flow passage
“…The stability of the nanofluid was also confirmed by UV/VIS spectroscopy. The absorbance reading will rise as the amount of dispersed GAMWCNTs increases, and the relative concentration of GAMWCNTs remains stable till 60 days 38 . Figure 4 ( a , b ) TEM images of pristine MWCNTs and GAMWCNTs (reuse with permission of elsevier).…”
Section: Resultsmentioning
confidence: 99%
“…Natural phenolic extract 3,4,5 trihydroxy benzoic acid, also known as gallic acid (GA), was used to covalently functionalize multiwall carbon nanotubes (diameter: < 8 nm, purity: > 95%, SSA: > 500 m 2 /g). A two-step method, as suggested by Akram et al 38 was introduced for preparation of green gallic acid treated multiwall carbon nanotubes nanofluid. 5 g of immaculate multi-wall carbon nanotubes (Nanostructured & Amorphous Materials Inc.), and 15 g of gallic acid were immersed into a beaker filled with 1000 ml distilled water and then stirred for almost 1/4 h until the mixture turned homogeneous.…”
The use of solar energy is one of the most prominent strategies for addressing the present energy management challenges. Solar energy is used in numerous residential sectors through flat plate solar collectors. The thermal efficiency of flat plate solar collectors is improved when conventional heat transfer fluids are replaced with nanofluids because they offer superior thermo-physical properties to conventional heat transfer fluids. Concentrated chemicals are utilized in nanofluids' conventional synthesis techniques, which produce hazardous toxic bi-products. The present research investigates the effects of novel green covalently functionalized gallic acid-treated multiwall carbon nanotubes-water nanofluid on the performance of flat plate solar collectors. GAMWCNTs are highly stable in the base fluid, according to stability analysis techniques, including ultraviolet–visible spectroscopy and zeta potential. Experimental evaluation shows that the thermo-physical properties of nanofluid are better than those of base fluid deionized water. The energy, exergy and economic analysis are performed using 0.025%, 0.065% and 0.1% weight concentrations of GAMWCNT-water at varying mass flow rates 0.010, 0.0144, 0.0188 kg/s. The introduction of GAMWCNT nanofluid enhanced the thermal performance of flat plate solar collectors in terms of energy and exergy efficiency. There is an enhancement in efficiency with the rise in heat flux, mass flow rate and weight concentration, but a decline is seen as inlet temperature increases. As per experimental findings, the highest improvement in energy efficiency is 30.88% for a 0.1% weight concentration of GAMWCNT nanofluid at 0.0188 kg/s compared to the base fluid. The collector's exergy efficiency increases with the rise in weight concentration while it decreases with an increase in flow rate. The highest exergy efficiency is achieved at 0.1% GAMWCNT concentration and 0.010 kg/s mass flow rate. GAMWCNT nanofluids have higher values for friction factor compared to the base fluid. There is a small increment in relative pumping power with increasing weight concentration of nanofluid. Performance index values of more than 1 are achieved for all GAMWCNT concentrations. When the solar thermal collector is operated at 0.0188 kg/s and 0.1% weight concentration of GAMWCNT nanofluid, the highest size reduction, 27.59%, is achieved as compared to a flat plate solar collector with water as a heat transfer fluid.
“…The stability of the nanofluid was also confirmed by UV/VIS spectroscopy. The absorbance reading will rise as the amount of dispersed GAMWCNTs increases, and the relative concentration of GAMWCNTs remains stable till 60 days 38 . Figure 4 ( a , b ) TEM images of pristine MWCNTs and GAMWCNTs (reuse with permission of elsevier).…”
Section: Resultsmentioning
confidence: 99%
“…Natural phenolic extract 3,4,5 trihydroxy benzoic acid, also known as gallic acid (GA), was used to covalently functionalize multiwall carbon nanotubes (diameter: < 8 nm, purity: > 95%, SSA: > 500 m 2 /g). A two-step method, as suggested by Akram et al 38 was introduced for preparation of green gallic acid treated multiwall carbon nanotubes nanofluid. 5 g of immaculate multi-wall carbon nanotubes (Nanostructured & Amorphous Materials Inc.), and 15 g of gallic acid were immersed into a beaker filled with 1000 ml distilled water and then stirred for almost 1/4 h until the mixture turned homogeneous.…”
The use of solar energy is one of the most prominent strategies for addressing the present energy management challenges. Solar energy is used in numerous residential sectors through flat plate solar collectors. The thermal efficiency of flat plate solar collectors is improved when conventional heat transfer fluids are replaced with nanofluids because they offer superior thermo-physical properties to conventional heat transfer fluids. Concentrated chemicals are utilized in nanofluids' conventional synthesis techniques, which produce hazardous toxic bi-products. The present research investigates the effects of novel green covalently functionalized gallic acid-treated multiwall carbon nanotubes-water nanofluid on the performance of flat plate solar collectors. GAMWCNTs are highly stable in the base fluid, according to stability analysis techniques, including ultraviolet–visible spectroscopy and zeta potential. Experimental evaluation shows that the thermo-physical properties of nanofluid are better than those of base fluid deionized water. The energy, exergy and economic analysis are performed using 0.025%, 0.065% and 0.1% weight concentrations of GAMWCNT-water at varying mass flow rates 0.010, 0.0144, 0.0188 kg/s. The introduction of GAMWCNT nanofluid enhanced the thermal performance of flat plate solar collectors in terms of energy and exergy efficiency. There is an enhancement in efficiency with the rise in heat flux, mass flow rate and weight concentration, but a decline is seen as inlet temperature increases. As per experimental findings, the highest improvement in energy efficiency is 30.88% for a 0.1% weight concentration of GAMWCNT nanofluid at 0.0188 kg/s compared to the base fluid. The collector's exergy efficiency increases with the rise in weight concentration while it decreases with an increase in flow rate. The highest exergy efficiency is achieved at 0.1% GAMWCNT concentration and 0.010 kg/s mass flow rate. GAMWCNT nanofluids have higher values for friction factor compared to the base fluid. There is a small increment in relative pumping power with increasing weight concentration of nanofluid. Performance index values of more than 1 are achieved for all GAMWCNT concentrations. When the solar thermal collector is operated at 0.0188 kg/s and 0.1% weight concentration of GAMWCNT nanofluid, the highest size reduction, 27.59%, is achieved as compared to a flat plate solar collector with water as a heat transfer fluid.
Herein, we present for the first time a quick, easy, effective, and green method for preparing green nanofluids containing silver nanoparticles. The solution plasma method with a high-voltage DC power source and extracts from the Paramignya trimera was employed to prepare silver nanoparticles. The obtained results showed that silver nanoparticles were spherical, with a small average size of − 8 nm and fairly uniformly dispersed in solution. Surface plasmon resonance spectra show a strong peak at 410 nm for the prepared samples. The Fourier transform infrared spectra revealed the presence of possible functional groups on the surface of silver nanoparticles. Furthermore, the formation mechanism of silver nanoparticles is also proposed. The effect of the preparation times on the thermal conductivity of nanofluid was also investigated. As a result, the nanofluids prepared with longer preparation times had higher thermal conductivity and the highest improvement of 18.3% was obtained for the nanofluid using 4 min preparation compared to the base fluid. The obtained results indicate promise for a simple, fast, and environmentally friendly method for producing nanofluids containing silver nanoparticles with high thermal conductivity for potential applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
