Promoting aqueous and transport characteristics of highly reactive nanoscale zero valent iron via different layered hydroxide coatings

A comprehensive survey of the literature in the area of numerical heat transfer (NHT) published between 2000 and 2009 has been conducted Due to the immenseness of the literature volume, the survey

Literature Survey of Numerical Heat Transfer (2000–2009): Part II

A lattice Boltzmann (LB) simulation strategy is proposed for the incompressible transport phenomena occurring during macroscopic solidification of pure substances. The proposed model is derived by coupling a passive scalar-based thermal LB model with the classical enthalpy–porosity technique for solid–liquid phase-transition problems. The underlying hydrodynamics are monitored by a conventional single-particle density distribution function (DF) through a kinetic equation, whereas the thermal field is obtained from another kinetic equation which is governed by a separate temperature DF. The phase-changing aspects are incorporated into the LB model by inserting appropriate source terms in the respective kinetic equations through the most formal technique following the extended Boltzmann equations along with an appropriate enthalpy updating scheme. The proposed model is validated extensively with one- and two-dimensional solidification problems for which analytical and numerical results are available in the ...

Lattice Boltzmann Simulation of Incompressible Transport Phenomena in Macroscopic Solidification Processes

Experimental and numerical study of single and two-phase flow and heat transfer in aluminum foams

An experimental method was used for validating the heat transfer within phase change materials (PCMs). The two models, enthalpy and effective heat capacity models, were implemented and three impact factors were analyzed. The results showed that it should not calculate using the same temperature range for the PCMs with different melting and freezing ranges. Narrower temperature range can make the enthalpy method more accurate. Also, the liquid fraction should be taken into account if the phase change had not completed. In addition, the proper treatment of latent heat made the effective heat capacity method more accurate than the enthalpy method.

Impact Factors Analysis of the Enthalpy Method and the Effective Heat Capacity Method on the Transient Nonlinear Heat Transfer in Phase Change Materials (PCMs)

Tailored transition temperature plastic crystals with enhanced thermal energy storage capacity

The present work explores the feasibility of using polyalcohols with solid-solid phase transition as active supporting matrix of n-alkanes in shape-stabilized phase change materials (SSPCMs). It is well-established that the use of SSPCM avoids leakage and increases stability and easy handling of solid-liquid PCMs. Nevertheless, the resulting composite exhibits a loss of heat storage capacity due to the volume occupied by the supporting material, which does not contribute to latent heat storage. Therefore, the objective of this work is to combine solid-liquid PCMs (alkanes) with solid-solid PCMs (polyalcohols), both exhibiting a phase transition in the same range of temperature, to obtain high energy density SSPCMs. Towards that goal, the performance of Neopentyl Glycol (NPG) and Docosane as a new energetic SSPCM has been proved. The NPG-Docosane chemical compatibility and its outstanding wettability facilitate the propitious association of both materials. The higher capillary forces obtained by decreasing the NPG crystal size together with the addition of expanded graphite (EG) allowed to obtain a maximum Docosane content of 60 wt%. The addition of EG improves the shape stability at the time that increases the heat transfer properties of the composites. The analysis showed that the components of the obtained SSPCMs are able to combine their latent heats, achieving a maximum value of 210.74 J/g for the highest Docosane content. This value is much higher than those latent heats exhibited by existing SSPCMs in the same working temperature range.

Neopentyl Glycol as Active Supporting Media in Shape-Stabilized PCMs.

This paper aims at an accurate description of the thermal behaviour of shape-stabilized phase change material by a low-dimensional set of ordinary differential equations. The proposed method is based on the use of a suitable proper basis allowing identification of some few dominant components, so that a low-dimensional approximate description of the melting/solidification problem is obtained by projection of the initial infinite-dimensional model on the dominant eigenfunctions of the basis. The basis results from proper orthogonal decomposition of a quadratic function whose meaning is close to that of the thermal field covariance and which is calculated by solving a simple Lyapunov equation. The method provides optimal low-dimensional models in the sense of unitary norms of the approximation error.

A Spectral Method for Low-Dimensional Description of Melting/Solidification Within Shape-Stabilized Phase-Change Materials

This work aims to characterize phase change materials (PCM) for thermal energy storage in buildings (thermal comfort). Fatty acids, biobased organic PCM, are attractive candidates for integration into active or passive storage systems for targeted application. Three pure fatty acids (capric, myristic and palmitic acids) and two eutectic mixtures (capric-myristic and capric-palmitic acids) are studied in this paper. Although the main storage properties of pure fatty acids have already been investigated and reported in the literature, the information available on the eutectic mixtures is very limited (only melting temperature and enthalpy). This paper presents a complete experimental characterization of these pure and mixed fatty acids, including measurements of their main thermophysical properties (melting temperature and enthalpy, specific heats and densities in solid and liquid states, thermal conductivity, thermal diffusivity as well as viscosity) and the properties of interest regarding the system integrating the PCM (energy density, volume expansion). The storage performances of the studied mixtures are also compared to those of most commonly used PCM (salt hydrates and paraffins).

Jean-Luc Dauvergne

Papers

Tailored transition temperature plastic crystals with enhanced thermal energy storage capacity

Neopentyl Glycol as Active Supporting Media in Shape-Stabilized PCMs.

A Spectral Method for Low-Dimensional Description of Melting/Solidification Within Shape-Stabilized Phase-Change Materials

Characterization of Fatty Acids as Biobased Organic Materials for Latent Heat Storage.

Fast estimation of the enthalpy–temperature function of Phase Change Materials