| 1. |
- Zehri, Abdelhafid, 1989, et al.
(författare)
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Graphene Oxide and Nitrogen-Doped Graphene Coated Copper Nanoparticles in Water-Based Nanofluids for Thermal Management in Electronics
- 2022
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Ingår i: JOURNAL OF NANOFLUIDS. - : American Scientific Publishers. - 2169-432X .- 2169-4338. ; 11:1, s. 125-134
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Tidskriftsartikel (refereegranskat)abstract
- Graphene oxide (GO) and nitrogen-doped graphene (NG) coated copper nanoparticles (NPs) have been developed in this work and investigated as nanofiller for water as Heat Transfer Fluids (HTFs). The morphology and composition of the coating were characterized to confirm the presence of functional groups and the nitrogen-doping of the graphene coating. Different fractions of the two types of coated nanoparticles NPs between 0.1 and 10 wt.% were dispersed in water. The thermal conductivity of the dispersions was evaluated at temperatures between 20 and 50 degrees C. A positive correlation between the thermal conductivity of the HTFs and the fraction and temperature are observed as a result of the increase of the solid phase contribution into the heat transfer. At a concentration of 0.5 wt.%, the thermal conductivity of the NG-CuNPs nanofluid reached its maximum increase of 78%, compared to a 13% increase in the case of GO-CuNPs. However, due to the poor stability of the NG-CuNPs, further increase of the solid phase did not result in any additional improvement. In contrast, the thermal conductivity of the GO-based dispersion resulted in a 103% enhancement at 10 wt.% at a temperature of 50 degrees C.
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| 2. |
- Wang, Jin, et al.
(författare)
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Investigation of mixed convection in an enclosure filled with nanofluids of Al2O3 –water and graphene-ethylene glycol
- 2019
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Ingår i: Journal of Nanofluids. - : American Scientific Publishers. - 2169-432X. ; 8:2, s. 337-348
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Tidskriftsartikel (refereegranskat)abstract
- In this research work, heat transfer enhancement of mixed convection in an enclosure is investigated with a moving top wall. Numerical simulations based on an Al2 O3 –water nanofluid are conducted by using variable thermophysical properties. Flow fields and temperature distributions are analyzed by considering effects of two partially heated walls. Moreover, water–ethylene glycol mixed with graphene nanoplatelets (GnP-WEG) is also considered to analyze effects of the heating procedure, Reynolds number, Rayleigh number and volume fraction of the nanoparticles, as well as on the heat transfer enhancement. It is found that there is a velocity difference between the pure water and the Al2 O3 –water nanofluid due to the increase of the fluid viscosity by an injection of Al2 O3 nanoparticles into the water. Moreover, flow patterns are significantly affected by the Reynolds number and the Rayleigh number. The heat transfer in the enclosure is enhanced by the increase of the top wall moving velocity. Although heat transfer enhancement for most cases are obtained by increasing the volume fraction of graphene nanoplatelets, a mixture of 0.25% graphene nanoplatelets and the water–ethylene glycol (the base fluid) provides the largest enhancement of heat transfer at low Reynolds number (Re = 1).
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| 3. |
- Wang, Zhe, et al.
(författare)
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Effects of graphene ethylene glycol/water nanofluids on the performance of a brazed plate heat exchanger
- 2018
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Ingår i: Journal of Nanofluids. - : American Scientific Publishers. - 2169-432X. ; 7:6, s. 1069-1074
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Tidskriftsartikel (refereegranskat)abstract
- Effects of graphene ethylene glycol/water nanofluids as the hot side fluid on heat transfer and pressure drop characteristics in a brazed plate heat exchanger (BPHE) were experimentally investigated. Nanofluid properties, especially thermal conductivity and viscosity of the graphene nanofluids were measured at various graphene concentrations (0.01 to 1.0% wt.) and temperatures (10 to 60 °C). Dimensionless Nusselt number and friction factors were used to compare the performances of the BPHE with and without graphene addition. Experimental analysis showed that the heat transfer performance is improved by an increase in Reynolds number and flow velocity and with a decrease in nanofluid concentration. The graphene nanofluids at 0.01 to 0.1% wt. brings an acceptable pressure drop penalty, but with a higher heat transfer performance than the base fluid in the BPHE. At a fixed flow velocity, the graphene nanofluids with proper concentrations give an increase about 4% to 7% in the heat transfer coefficients, which reveals that the graphene nanofluids can be a useful working medium in the BPHE. The increase in pressure drop is moderate under these experimental conditions which favours graphene nanofluids to be used in BPHEs for thermal systems.
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