Thermal conductivity of carbon nanotubes and their polymer nanocomposites: A review

1: Magnetic Particles: Preparation, Properties and Applications: M. Ozaki. 2: Maghemite (gamma-Fe2O3): A Versatile Magnetic Colloidal Material C.J. Serna, M.P. Morales. 3: Dynamics of Adsorption and Oxidation of Organic Molecules on Illuminated Titanium Dioxide Particles Immersed in Water M.A. Blesa, R.J. Candal, S.A. Bilmes. 4: Colloidal Aggregation in Two-Dimensions A. Moncho-Jorda, F. Martinez-Lopez, M.A. Cabrerizo-Vilchez, R. Hidalgo Alvarez, M. Quesada-PMerez. 5: Kinetics of Particle and Protein Adsorption Z. Adamczyk.

Surface and Colloid Science

Fast Fourier Transform

Educators, researchers, and policy makers have advocated student involvement for some time as an essential aspect of meaningful learning. In the past twenty years engineering educators have implemented several means of better engaging their undergraduate students, including active and cooperative learning, learning communities, service learning, cooperative education, inquiry and problem-based learning, and team projects. This paper focuses on classroom-based pedagogies of engagement, particularly cooperative and problem-based learning. It includes a brief history, theoretical roots, research support, summary of practices, and suggestions for redesigning engineering classes and programs to include more student engagement. The paper also lays out the research ahead for advancing pedagogies aimed at more fully enhancing students’ involvement in their learning.

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Pedagogies of Engagement: Classroom-Based Practices

Temperature (T) is probably the most fundamental parameter in all kinds of science. Respective sensors are widely used in daily life. Besides conventional thermometers, optical sensors are considered to be attractive alternatives for sensing and on-line monitoring of T. This Review article focuses on all kinds of luminescent probes and sensors for measurement of T, and summarizes the recent progress in their design and application formats. The introduction covers the importance of optical probes for T, the origin of their T-dependent spectra, and the various detection modes. This is followed by a survey on (a) molecular probes, (b) nanomaterials, and (c) bulk materials for sensing T. This section will be completed by a discussion of (d) polymeric matrices for immobilizing T-sensitive probes and (e) an overview of the various application formats of T-sensors. The review ends with a discussion on the prospects, challenges, and new directions in the design of optical T-sensitive probes and sensors.

Luminescent probes and sensors for temperature.

A numerical study was conducted on the spreading behavior of liquid drops on flat solid surfaces. The model predicts the shape of liquid-vapor interface under static equilibrium using an unstructured surface grid composed of triangular elements. Incremental movement of base contour, i.e. solid-liquid-vapor contact line, is also captured such that the constrained boundary conditions, i.e. advancing and receding contact angles, can be satisfied. The numerical model is applied to a common experiment that studies the behavior of liquid drops on inclined surfaces, where the shape of the drops change in response to an alteration of total volume or gravitational direction. On a heterogeneous surface that has contact angle hysteresis, the shape of the base contour on the solid surface is not determined uniquely but rather dependent upon history. This study demonstrates such dependence by comparing the spreading of a liquid drop on a solid surface with different quasi-equilibrium paths.Copyright © 2009 by ASME

Numerical Modeling of Liquid Drop Spreading Behavior on Inclined Surfaces

Minimizing water retention on the air side of aluminum surfaces is important in the design and operation of efficient heat exchangers for heating, ventilation, air-conditioning and refrigeration (HVAC&R) systems. Accumulation of water degrades the performance of heat exchangers by lowering the heat transfer rate and increasing the pressure drop. As a result, power consumption in such systems increases. In this work, a method of fabricating liquid-infused slippery surfaces with honeycomb-like superhydrophobic micro-/nano-structure substrate via an anodization process is developed. The slippery surface exhibits superhydrophobicity with a contact angle of 155° and a sliding angle smaller than 5°. The delay of ice formation is observed during condensation/frosting experiment. Frost-melt retention experiments show that the liquid-infused slippery surface reduces the water retention by 90% compared to an untreated specimen. The longevity of the slippery surface is also explored. The water retention ratio does not show a significant change after 60 frosting/defrosting cycles, and is still only one third that of the baseline. The slippery surface has potential in HVAC&R applications.Copyright © 2015 by ASME

Water-Repellent Slippery Surfaces for HVAC&R Systems

Local and average heat transfer behavior for a falling film on horizontal flat tubes is explored through an experimental approach in this work. Experiments are conducted using water (18 °C) under different heat fluxes and tube spacings, with a range of flow rates that covers all flow modes. It is found that the local heat transfer coefficient decreases with distance from the top of the tube and is almost constant along the axial direction. Heat flux and tube spacing have almost no effect on average heat transfer performance within the experimental range. The average Nusselt number for the flat tube is close to that for round tube in a droplet flow mode, but it is almost twice as large as the round-tube result in the jet mode and sheet modes.Copyright © 2011 by ASME

Heat Transfer Performance for a Falling-Film on Horizontal Flat Tubes

High-efficiency boilers: Condensation and transient behavior

Liquid-air-cycle-engine (LACE) systems have the potential to significantly reduce the operating cost of space exploration vehicles. High-performance compact heat exchangers are a critical technology for LACE and other advanced air-breathing propulsion systems. However, large performance gains over current state-of-practice ground-based heat exchangers are necessary to significantly reduce heat exchanger mass. Data and analysis are presented to show that operating advanced compact heat exchangers at much higher Reynolds numbers than previously considered results in these large performance gains. At high Reynolds numbers, the flow enters a turbulent vortex-shedding regime, and significant heat transfer enhancement results. Naphthalene sublimation technique is used to study heat transfer performance. Mass transfer experiments are conducted in a scaled-up offset-strip fin array at Reynolds numbers up to Re = 120,000. The measured and mass-transfer results show that the heat transfer coefficients in this type of heat exchanger are much higher than predicted by correlations developed using available low-Reynolds number data. Details of an apparatus in which air-liquefaction and enrichment experiments are currently being performed are also presented.

Anthony M. Jacobi

Papers

Numerical Modeling of Liquid Drop Spreading Behavior on Inclined Surfaces

Water-Repellent Slippery Surfaces for HVAC&R Systems

Heat Transfer Performance for a Falling-Film on Horizontal Flat Tubes

High-efficiency boilers: Condensation and transient behavior

Compact Heat Exchangers for Air Liquefaction in Propulsion Applications