An introduction to heat transfer

Introduction to heat transfer

Materials with hierarchical porosity and structures have been heavily involved in newly developed energy storage and conversion systems. Because of meticulous design and ingenious hierarchical structuration of porosities through the mimicking of natural systems, hierarchically structured porous materials can provide large surface areas for reaction, interfacial transport, or dispersion of active sites at different length scales of pores and shorten diffusion paths or reduce diffusion effect. By the incorporation of macroporosity in materials, light harvesting can be enhanced, showing the importance of macrochannels in light related systems such as photocatalysis and photovoltaics. A state-of-the-art review of the applications of hierarchically structured porous materials in energy conversion and storage is presented. Their involvement in energy conversion such as in photosynthesis, photocatalytic H 2 production, photocatalysis, or in dye sensitized solar cells (DSSCs) and fuel cells (FCs) is discussed. Energy storage technologies such as Li-ions batteries, supercapacitors, hydrogen storage, and solar thermal storage developed based on hierarchically porous materials are then discussed. The links between the hierarchically porous structures and their performances in energy conversion and storage presented can promote the design of the novel structures with advanced properties.

Hierarchically Structured Porous Materials for Energy Conversion and Storage

Heat transfer enhancement for thermal energy storage using metal foams embedded within phase change materials (PCMs)

Preparation and thermal characterization of paraffin/metal foam composite phase change material

A detailed experimental and analytical study has been performed to evaluate how copper porous foam (CPF) enhances the heat transfer performance in a cylindrical solid/liquid phase change thermal energy storage system. The CPF used in this study had a 95% porosity and the phase change material (PCM) was 99% pure eicosane. The PCM and CPF were contained in a vertical cylinder where the temperature at its radial boundary was held constant, allowing both inward freezing and melting of the PCM. Detailed quantitative time-dependent volumetric temperature distributions and melt/freeze front motion and shape data were obtained. As the material changed phase, a thermal resistance layer built up, resulting in a reduced heat transfer rate between the surface of the container and the phase change front. In the freezing analysis, we analytically determined the effective thermal conductivity of the combined PCM/CPF system and the results compared well to the experimental values. The CPF increased the effective thermal conductivity from 0.423 W/m K to 3.06 W/mK. For the melting studies, we employed a heat transfer scaling analysis to model the system and develop heat transfer correlations. The scaling analysis predictions closely matched the experimental data of the solid/liquid interface position and Nusselt number.

Phase Change Heat Transfer Enhancement Using Copper Porous Foam

Similarity Solutions of Natural Convection With Internal Heat Generation

Entropy generation in a transitional boundary layer region under the influence of freestream turbulence using transitional RANS models and DNS

Josef Stefan: His life and legacy in the thermal sciences

Analytical solutions to the Stefan problem with internal heat generation

John Crepeau

Papers

Phase Change Heat Transfer Enhancement Using Copper Porous Foam

Similarity Solutions of Natural Convection With Internal Heat Generation

Entropy generation in a transitional boundary layer region under the influence of freestream turbulence using transitional RANS models and DNS

Josef Stefan: His life and legacy in the thermal sciences

Analytical solutions to the Stefan problem with internal heat generation