Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

Chemistry of Carbon Nanotubes

We review the present state of polymer nanocomposites research in which the fillers are single-wall or multiwall carbon nanotubes. By way of background we provide a brief synopsis about carbon nanotube materials and their suspensions. We summarize and critique various nanotube/polymer composite fabrication methods including solution mixing, melt mixing, and in situ polymerization with a particular emphasis on evaluating the dispersion state of the nanotubes. We discuss mechanical, electrical, rheological, thermal, and flammability properties separately and how these physical properties depend on the size, aspect ratio, loading, dispersion state, and alignment of nanotubes within polymer nanocomposites. Finally, we summarize the current challenges to and opportunities for efficiently translating the extraordinary properties of carbon nanotubes to polymer matrices in hopes of facilitating progress in this emerging area.

Polymer Nanocomposites Containing Carbon Nanotubes

The boundary layer equations for plane, incompressible, and steady flow are 

$$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Boundary Layer Theory

Initial-value ordinary differential equation solution via variable order Adams method (SIVA/DIVA) package is collection of subroutines for solution of nonstiff ordinary differential equations. There are versions for single-precision and double-precision arithmetic. Requires fewer evaluations of derivatives than other variable-order Adams predictor/ corrector methods. Option for direct integration of second-order equations makes integration of trajectory problems significantly more efficient. Written in FORTRAN 77.

Solving Ordinary Differential Equations

Cerium dioxide (CeO2, ceria) is becoming an ubiquitous constituent in catalytic systems for a variety of applications. 2016 sees the 40th anniversary since ceria was first employed by Ford Motor Company as an oxygen storage component in car converters, to become in the years since its inception an irreplaceable component in three-way catalysts (TWCs). Apart from this well-established use, ceria is looming as a catalyst component for a wide range of catalytic applications. For some of these, such as fuel cells, CeO2-based materials have almost reached the market stage, while for some other catalytic reactions, such as reforming processes, photocatalysis, water-gas shift reaction, thermochemical water splitting, and organic reactions, ceria is emerging as a unique material, holding great promise for future market breakthroughs. While much knowledge about the fundamental characteristics of CeO2-based materials has already been acquired, new characterization techniques and powerful theoretical methods are dee...

Fundamentals and Catalytic Applications of CeO2-Based Materials

The influence of radiative heat transfer in a CO2 pipe flow is numerically investigated at different pressures.Coupled heat and mass transfer, including radiation transport, are modeled. The physical models and the high temperature and high pressure radiative properties method of computation are presented. Simulations are conducted for pure CO2 flows in a high temperature pipe at 1100 K (with radius 2 cm) with a fixed velocity (1 m·s-1) and for di erent operating pressures, 0:1, 1, 5 and 20 MPa (supercritical CO2). The coupling between the temperature and velocity fields is discussed and it is found that the in uence of radiation absorption is important at low pressure and as the operating pressure increases above 5 MPa the influence of radiation becomes weaker due to an increase of CO2 optical thickness.

Pressurized Carbon Dioxide as Heat Transfer Fluid: In uence of Radiation on Turbulent Flow Characteristics in Pipe

EVOLUTION OF THE HOMOGENIZED VOLUMETRIC RADIATIVE PROPERTIES OF A FAMILY OF α -SiC FOAMS WITH GROWING NOMINAL PORE DIAMETER

Using group A particle suspensions as heat transfer fluid in concentrated solar power plants leads to higher efficiency and lower costs. Combined cycle power generation becomes possible with e.g. a topping Brayton air turbine cycle and an advanced steam power block as bottoming cycle. This hybrid combined cycle solar tower power plant will be tested on a 3 MWth pilot-scale at the CNRS-Themis solar tower (France) with the receiver, hot powder storage and air Brayton turbine. The suspension will exit the receiver at a nominal outlet temperature of 750-800°C. Hot powders will be stored and will subsequently exchange heat with the turbine air. The outlet temperature of the air heat exchanger (625 to 700 °C) will considerably determine the hybrid operation (reducing the possibly used fossil fuel boost) and the heat exchanger design is of paramount importance. The air heat exchanger will be a baffled cross-flow fluidized bed. Air will be heated in an in-bed finned-tube bundle. Air will be fed at 5.8 bar and∼270°C. The hydrodynamics and heat transfer characteristics of the air heat exchanger were experimentally investigated towards bubble properties and heat trasnfer coefficient. The bed to tube heat transfer coefficient was measured for different pipe geometries at bed temperatures up to 700 °C, exceeding 2 kW/m2K for a twin-bore finned tube but only about 650 W/m²K for the bare tube of equal outside diameter. The heat transfer coefficient from the tube wall to the turbulent air flow inside the tube (∼ 325 W/m2K) determines the design. NEPTUNE_CFD software was used to perform 3D-numerical simulations of the fluidized bed hydrodynamics via an Eulerian n-fluid approach. Simulation and experimental results were in very fair agreement, stressing the capability of mathematical models to predict the behaviour of a cross-flow bubbling fluidized bed.

The fluidized bed air heat exchanger in a hybrid Brayton-cycle solar power plant

Volumetric receivers made of metallic wire meshes are a promising technology that allows different designs and configurations. In this paper the local volumetric heat transfer coefficient for a volumetric absorber with two extreme arrangements, inline and stagger, is presented. The results show that the heat transfer rates for the stagger stack is nearly two times higher than the inline stack. Moreover, the local volumetric heat transfer coefficient is implemented in a Homogeneous Equivalent Model using a Local Thermal Non-Equilibrium model to compare the results. The stagger stack performs better than the inline stack despite their higher frontal losses and pressure drop. Finally, a validation of the Homogeneous Equivalent Model is carried out with experimental data showing a good agreement.

Numerical simulation of convective heat transfer for inline and stagger stacked plain-weave wire mesh screens and comparison with a local thermal non-equilibrium model

Gilles Flamant

Papers

Pressurized Carbon Dioxide as Heat Transfer Fluid: In uence of Radiation on Turbulent Flow Characteristics in Pipe

EVOLUTION OF THE HOMOGENIZED VOLUMETRIC RADIATIVE PROPERTIES OF A FAMILY OF α -SiC FOAMS WITH GROWING NOMINAL PORE DIAMETER

The fluidized bed air heat exchanger in a hybrid Brayton-cycle solar power plant

Numerical simulation of convective heat transfer for inline and stagger stacked plain-weave wire mesh screens and comparison with a local thermal non-equilibrium model

Kinetic, thermal and chemical attrition of manganese chloride particles in a fluidized bed