Hammad Younes

Effects of alignment, pH, surfactant, and solvent on heat transfer nanofluids containing Fe2O3 and CuO nanoparticles

In this paper, the effects of alignment, pH, surfactant and solvent on heat transfer nanofluids containing Fe2O3 and CuO nanoparticles are studied and analyzed. The microscope images show that Fe2O3 could form some kind of alignment spontaneously in water even without external magnetic field. With the addition of external magnetic field, the alignment is strengthened. In water, the magnetic particle agglomeration to larger size occurs easily, which makes the directional alignment much faster and easier. Ethylene glycol solvent and chemical surfactant sodium dodecyl benzene sulfonate, NaDDBS could separate the Fe2O3 and CuO nanoparticles well in the fluids and avoid possible aggregation. Therefore, magnetic alignments are hard to observe. The measured thermal conductivities of each individual sample coincide with the microscope images and assumptions. In addition, pH values of Fe2O3 and CuO nanoparticles are measured and it has been determined that at those pH values, thermal conductivities of those nanopa...

Tribological properties of carbon nanotube grease

Purpose – The purposes of this paper are to prepare the carbon nanotube (CNT) grease, to contrast the tribology properties of the CNT grease with the original grease and to find the lubricating mechanism of the CNT grease. Design/methodology/approach – The CNTs (single-wall and multi-wall) are added into the polyalphaolefin oils (DURASYN_166) to form stable and homogeneous CNT grease with potential heat transfer, conductive and lubricative properties. The friction of this new type of CNT grease was determined by wear experiments under three conditions: dry friction, with the base oil grease and with the CNT grease. Findings – The research is about the tribological properties of CNT greases; it shows better lubricating performance and wear resistance than the base oil grease. The performance improvement of CNT grease is owing to the unique hexagonal structure and the high thermal conductivity of CNTs. Originality/value – The paper documents that CNTs can obviously improve the lubricating effect of grease, ...

Effects of solvent hydrogen bonding, viscosity, and polarity on the dispersion and alignment of nanofluids containing Fe2O3 nanoparticles

It has been shown that the alignment of Iron (III) oxide (Fe2O3) nanoparticles in water (H2O) can enhance the thermal conductivity of nanofluids. To better understand solvent effects such as hydrogen bonding, viscosity, and polarity, nanofluids were prepared by mixing Fe2O3 nanoparticles and various solvents (water, ethanol, 1-propanol, isopropanol, 2-propanone, hexane, cyclohexane, ethylene glycol, glycerol, etc.), and the dispersions and alignments of the Fe2O3 nanoparticles in these solvents with and without an applied magnetic field were investigated using an optical microscope. The microscope images indicated that inter-molecule hydrogen bonding of the solvents with one OH group (water, ethanol, 1-propanol, and isopropanol) could help to disperse and align the Fe2O3 nanoparticles. The intra-molecular hydrogen bonding causes a dramatic increase in viscosity for fluids with multiple OH groups, such as ethylene glycol (C2H6O2) and glycerol (C3H8O3), and makes the Fe2O3 nanoparticles dispersion and align...

Optimizing the dispersion conditions of SWCNTs in aqueous solution of surfactants and organic solvents

The optimum concentration of surfactants in aqueous medium and the optimum sonication time for organic medium to achieve the best dispersion of SWCNTs are investigated in this study. Scanning electron microscope (SEM), atomic force microscope (AFM), and UV-vis-NIR study show that the optimum surfactant concentrations to achieve best dispersion for 0.25mg/mL of SWCNTs are 9-10mg/mL for (sodium dodecylbenzenesulfonate (SDBS)) and 8-9mg/mL for (sodium deoxycholate (DOC)). The diameter of the SWCNT lies between 0.7 and 2.5nm in the case of aqueous solvent, which is in good agreement with the chirality. Moreover, SEM analysis reveals the presence of well-dispersed nanotubes along with some amount of surfactant particles; that is, some nanotubes might be covered with surfactants. Best dispersion of SWCNTs in organic solvents (1,2-Dichloroethane (DCE) and N,N-Dimethylformamide (DMF)) is achieved by four hours of tip sonication. It realized that organic solvents provide pure SWCNTs after drying, which may possibly have SWCNTs with intrinsic properties.

Plasmonic nanofluids enhanced solar thermal transfer liquid

Plasmonic nanostructures suspended in a liquid are known to offer enhanced absorption of light and improved photo-thermal efficiency comparing with conventional solar absorbers. This approach localizes high temperatures to the interior of the liquid through efficient trapping of incoming light via scattering and absorption mechanisms. Theoretical studies show that Ag exhibits the highest efficiency of plasmonic excitations, and the plasmonic absorption band can be shifted to cover the visible wavelength ranges by loading the Ag NPs onto silica core. In this work, silica-core decorated with Ag NPs are synthesized through the chemical reduction method and their morphological and optical properties are characterized using transmission electron microscope (TEM) and UV-Vis-NIR spectrophotometer. The characterization results show the potentials of light absorbing plasmonic metal-dielectric nanoparticles suspended in water for producing steam at high efficiencies upon solar illumination. The experimental work su...

Carbon nanomaterials based TSVs for dual sensing and vertical interconnect application

We discuss fabrication and characterization of TSVs filled with carbon nano-materials (CNM) for dual function of sensing and vertical interconnect for hostile environment applications (Corrosive High Temperature and Pressure). Nano-composites, made by functionalization of CNTs were integrated using dispersion in epoxy resin and inkjet techniques to fill up the TSVs and provide sensing surface. The results reveal ability for the nano-composite to fill vias with electrical conductivity path and sensing established through the wafer backside.

Carbon Nanostructure‐Based Scale Sensors Using Inkjet Printing and Casting Techniques

In this chapter, the fabrication and characterization of scale sensor using carbon nanotubes (CNTs) are discussed. Two different methods are used to prepare the carbon nanomaterials for the sensor fabrication: CNT casting and the CNT inkjet printing. In addition, the sensors are integrated into Kelvin architectures. The electrical resistance of the carbon nanomaterial films is measured with and without adding a drop of brine to the surface of the film. The films are characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), and energy dispersive X‐ray spectroscopy (EDS). Electrical resistance of the casted CNT films and five layers of CNT inkjet printing are found to be close to 40.0 kΩ and 1.00 kΩ, respectively. Adding one drop of brine solution on the surface of the casted CNT film and five layers of CNT inkjet printing changed the resistance by 50% and 75%, respectively. The resetting process is done for all sensors by soaking in deionized water (DI water) for some time, and the electrical resistance is measured and found to be close to the initial electrical resistance.

Effect of Saline Solution on the Electrical Response of Single Wall Carbon Nanotubes-Epoxy Nanocomposites

The effects of saline solution on the electrical resistance of single wall carbon nanotubes-epoxy nanocomposites have been investigated experimentally. Ultrasonic assisted fabricated 1.0% and 0.5 W/W% SWCNTs epoxy nanocomposites are integrated into a Kelvin structure by smear cast the nanocomposites on a glass wafer. Four metal pads are deposited on the nanocomposites using the beam evaporator and wires are tethered using soldering. The effect of saline solution on the electrical resistance of the nanocomposites is studied by adding drop of saline solution to the surface of the fabricated nanocomposites and measuring electrical resistance. Moreover, the nanocomposites are soaked completely into 3 wt.% saline solution and real-time measurement of the electrical resistance is conducted. It is found that a drop of saline solution on the surface of the nanocomposites film increases the resistance by 50%. Furthermore, the real-time measurement reveals a 40% increase in the resistance of the nanocomposites film. More importantly, the nanocomposites are successfully reset by soaking in DI water for four hours. This study may open the door for using SWCNTs epoxy nanocomposites as scale sensors in oil and gas industry.

Nanofluids Based on Carbon Nanostructures

A nanofluid consists in a liquid suspension of nanometer-sized particles. These fluids may contain (or not) surface-active agents to aid in the suspension of the particles. Nanometer-sized particles have higher thermal conductivity than the base fluids. Oxides, metals, nitrides, and nonmetals, like carbon nanotubes, can be used as nanoparticles in nanofluids. Water, ethylene glycol, oils, and polymer solutions can be used as base fluids. In this chapter, we summarize the recent studies of using CNTs and graphene to improve the thermal conductivity of nanofluids. Moreover, we refer to the studies about the effect of using magnetic fields on enhancing the thermal conductivity of nanofluids. Too much discrepancy about thermal conductivity of nanofluids can be found in the literature. For carbon nanofluids, unfortunately, no significant improvements on thermal conductivi‐ ty are observed using low concentrations. Different improvement percentages have been reported. This variation in the thermal conductivity can be attributed to many factors, such as particle size temperature, pH, or zeta potential. We believe that more research efforts need to be made in order to, first, improve the thermal conductivity of nano‐ fluids and, second, assess the effect of the different parameters and conditions on the thermal conductivity of nanofluids.