A review of studies using graphenes in energy conversion, energy storage and heat transfer development

Preparation of poly(vinyl alcohol)-grafted graphene oxide/poly(vinyl alcohol) nanocomposites via in-situ low-temperature emulsion polymerization and their thermal and mechanical characterization

Design and testing of a wave-rotor constant-volume combustor achieved stable combustion at near-atmospheric inlet conditions and demonstrated the potential of pressure-gain combustion using a wave ...

Experimental Test, Model Validation, and Viability Assessment of a Wave-Rotor Constant-Volume Combustor

Poly(vinyl alcohol)-grafted Graphene oxide (PVA-g-GO) as novel nanofillers were used to reinforce poly(vinyl alcohol) (PVA) composite fibers via simple wet spinning to promote homogeneous dispersion of reinforcing nanofillers as well as strengthen interfacial adhesion between nanofillers and matrix. Then the impact of these PVA chains grafted above GO sheets on the compatibility and dispersion of PVA-g-GO sheets in PVA fiber, the interfacial adhesion between nanofillers and matrix and the structure as well as property of PVA-g-GO/PVA fibers were studied systematically via characterizing morphology, aggregation structure and mechanical property of these composite fibers. These results showed that not only well dispersion and compatibility of PVA-g-GO sheets in composite fibers could be achieved, but also obvious enhancement in interfacial adhesion between nanofillers and matrix. Meanwhile, significant reinforcement in tensile strength and initial modulus of these composite fibers could also be obtained. Compared with neat PVA drawn fiber, tensile strength and initial modulus of these composite drawn fibers could increase by 39% and 69% with addition of 0.60 wt% of PVA-g-GO sheets, respectively. On the one hand, crystallization and orientation degree of these composite fibers could be improved because of the template-oriented effect of PVA-g-GO sheets during hot drawing. On the other hand, efficient load transfer between matrix and nanofillers in composite drawn fibers could be achieved easily because of the strong interfacial adhesion between nanofillers and matrix. These were also two main reasons for the obvious improvement in tensile strength and initial modulus of composite drawn fibers.

Enhanced tensile strength and initial modulus of poly(vinyl alcohol)/graphene oxide composite fibers via blending poly(vinyl alcohol) with poly(vinyl alcohol)-grafted graphene oxide

Experimental results from the Bath μ-wave rotor turbine performance tests

This study focuses on electrostatics of various graphene structures as graphene monolayer, graphene nanoribbons, as well as multi-layer graphene or graphene flakes. An atomistic moment method based on classical electrostatics is utilized in order to evaluate the charge distribution in each nanostructure. Assuming a freestanding graphene structure in an infinite or in a semi-infinite space limited by a grounded infinite plane, the effect of the length, width, number of layers and position of the nanostructure on its electrostatic charge distributions and total charge and capacitance is examined through a parametric analysis. The results of the present show good agreement with corresponding available data in the literature, obtained from different theoretical approaches. Performing nonlinear regression analysis on the numerical results, where it is possible, simple analytical expressions are proposed for the total charge and charge distribution prediction based on structure geometry.

Analytical expressions for electrostatics of graphene structures

In the present study, a buckling analysis of laminated composite rectangular plates reinforced with multiwalled carbon nanotube (MWCNT) inclusions is carried out using the finite element method (FEM). The rule of mixtures and the Halpin-Tsai model are employed to calculate the elastic modulus of the nanocomposite matrix. The effects of three critical factors, including random dispersion, waviness, and agglomeration of MWCNTs in the polymer matrix, on the material properties of the nanocomposite are analyzed. Then, the critical buckling loads of the composite plates are numerically determined for different design parameters, such as plate side-to-thickness ratio, elastic modulus ratio, boundary conditions, layup schemes, and fiber orientation angles. The influence of carbon nanotube fillers on the critical buckling load of a nanocomposite rectangular plate, considering the modified Halpin-Tsai micromechanical model, is demonstrated. The results are in good agreement with experimental and other theoretical data available in the open literature.

Design of Laminated Composite Plates with Carbon Nanotube Inclusions against Buckling: Waviness and Agglomeration Effects.

The propulsion demands of high-speed naval vessels often rely on gas turbines, producing significant amount of power achieving thus high performance requirements. Gas turbines can be used either to...

Gas turbine performance enhancement for naval ship propulsion using wave rotors

Abstract Wave rotors are rotating equipment designed to exchange energy between high and low enthalpy fluids by means of unsteady pressure waves. In turbomachinery, they can be used as topping devices to gas turbines aiming to improve performance. The integration of a wave rotor into a ground power unit is far more attractive than into an aeronautical application, since it is not accompanied by any inconvenience concerning the over-weight and extra dimensioning. Two are the most common types of ground industrial gas turbines: The one-shaft and the two-shaft engines. Cycle analysis for both types of gas turbine engines topped with a four-port wave rotor is calculated and their performance is compared to the performance of the baseline engine accordingly. It is concluded that important benefits are obtained in terms of specific work and specific fuel consumption, especially compared to baseline engines with low compressor pressure ratio and low turbine inlet temperature.

Performance Enhancement of One and Two-Shaft Industrial Turboshaft Engines Topped With Wave Rotors

Flows of variable viscosity fluids have many industrial applications in fluid mechanics and in engineering such as pump flows for highly viscous fluids. Carrying out a literature survey, it was found that in most cases the fluid viscosity is mainly temperature dependent. Numerical investigation of such flows involves the solution of the Navier-Stokes equations with an extra difficulty arising from the fact that the viscosity is not constant over the flow field. This article presents an analytical solution to the Navier-Stokes equations for the case of laminar flows in rotating systems with variable viscosity fluids. The equations are written in a cylindrical relative frame of reference rotating with a constant angular velocity. In the following, appropriate reference quantities are chosen to provide the non-dimensional form of the partial differential equations. The proposed solution that satisfies the continuity, the momentum and the energy equation, is expressed in terms of the Bessel function of the first kind and of exponential functions. Carrying out algebraic manipulations, it is proven that the proposed solution satisfies all the governing equations. Plots of the velocity, pressure and temperature distributions show the influence of the radius and of the axial coordinate to the flow field.

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A. Fatsis

Papers

Analytical expressions for electrostatics of graphene structures

Design of Laminated Composite Plates with Carbon Nanotube Inclusions against Buckling: Waviness and Agglomeration Effects.

Gas turbine performance enhancement for naval ship propulsion using wave rotors

Performance Enhancement of One and Two-Shaft Industrial Turboshaft Engines Topped With Wave Rotors

On The Exact Solution Of IncompressibleViscous Flows With Variable Viscosity