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.

Recent developments in materials have opened opportunities for non-metallic materials to be used for constructing heat exchangers. In particular, polymers can be superior to conventional metals in chemical resistance, weight, and material cost. While polymers generally have a very low thermal conductivity and are limited in mechanical strength and temperature, these drawbacks can be alleviated by reducing the characteristic lengths of the heat exchanger core. In this paper, the technical potential of a polymer-tube-bundle heat exchanger for liquid-to-gas applications is assessed. Design parameters of the polymer heat exchanger are determined to match the thermal-hydraulic performance of a conventional metallic heat exchanger under the same operating conditions. Results show that the polymer heat exchanger can achieve significantly reduced core weight and volume as well as material cost.

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Polymer-Tube-Bundle Heat Exchanger for Liquid-to-Gas Applications

The effect of condensate accumulation and shedding on the air-side thennal perfonnance of automotive evaporator coils has been studied. Experiments under wet and dry conditions were conducted to expose the impact of condensate on five different coils. Condensate retention data were collected in both real-time and at steady-state to quantitatively detennine how condensate load up on a coil surface. Sensible Colburn j factors and friction factors were calculated from the experimental data, and the relative perfonnance of different coils was discussed. A dynamic drainage test was developed to study the nature of water draining out of a heat exchanger. It was found the simple drainage test qualitatively predicted how much condensate would be retained by different coils under operating conditions. Current retention modeling techniques were adapted to include automotive evaporators.

Condensate Retention Effects on the Air-Side Heat Transfer Performance of Automotive Evaporator Coils

The effect of surface tension variation on filmwise condensation and heat transfer on a cylinder in cross flow

By their very nature, compact heat exchangers allow an efficient use of material, volume and energy in thermal systems. These benefits have driven heat exchanger design toward higher compactness, and the trend toward ultra-compact designs will continue. Highly compact surfaces can be manufactured using micromachining and other modern technologies. In this paper, unresolved thermalhydraulic issues related to ultra-compact designs will be discussed and the status of the technologies required for the production of ultra-compact structured surfaces will be summarized.

Meso- and Micro-Scale Frontiers of Compact Heat Exchangers

An air-side data analysis method is developed for flat-tube heat exchangers under partially wet conditions. In order to simplify the combined sensible and latent heat transfer, it is assumed that condensate drainage paths develop such that, at steady state, water does not spread to noncondensing surfaces, which therefore remain dry. The air dew point is compared to local fin-tip and fin-base temperatures, and a partially wet flat-tube heat exchanger is partitioned into fully wet, partially wet, and dry-fin regions, which are subsequently analyzed as separate heat exchangers. Using an enthalpy-based effectiveness–NTU (number of transfer units) method, average fin efficiency is calculated for each region, and the locations of region boundaries are determined iteratively. The proposed data analysis method is demonstrated with experimental data for a flat-tube louver-fin heat exchanger under various latent loads. The general approach presented can be extended to other heat exchanger geometries.

Anthony M. Jacobi

Papers

Polymer-Tube-Bundle Heat Exchanger for Liquid-to-Gas Applications

Condensate Retention Effects on the Air-Side Heat Transfer Performance of Automotive Evaporator Coils

The effect of surface tension variation on filmwise condensation and heat transfer on a cylinder in cross flow

Meso- and Micro-Scale Frontiers of Compact Heat Exchangers

A Simple Air-Side Data Analysis Method for Partially Wet Flat-Tube Heat Exchangers