Review on thermal energy storage with phase change: materials, heat transfer analysis and applications

Thermoelectric (TE) technology is regarded as alternative and environmentally friendly technology for harvesting and recovering heat which is directly converted into electrical energy using thermoelectric generators (TEG). Conversely, Peltier coolers and heaters are utilized to convert electrical energy into heat energy for cooling and heating purposes The main challenge lying behind the TE technology is the low efficiency of these devices mainly due to low figure of merit (ZT) of the materials used in making them as well as improper setting of the TE systems. The objective of this work is to carry out a comprehensive review of TE technology encompassing the materials, applications, modelling techniques and performance improvement. The paper has covered a wide range of topics related to TE technology subject area including the output power conditioning techniques. The review reveals some important critical aspects regarding TE device application and performance improvement. It is observed that the intensified research into TE technology has led to an outstanding increase in ZT, rendering the use TE devices in diversified application a reality. Not only does the TE material research and TE device geometrical adjustment contributed to TE device performance improvement, but also the use of advanced TE mathematical models which have facilitated appropriate segmentation TE modules using different materials and design of integrated TE devices. TE devices are observed to have booming applications in cooling, heating, electric power generation as well as hybrid applications. With the generation of electric energy using TEG, not only does the waste heat provide heat source but also other energy sources like solar, geothermal, biomass, infra-red radiation have gained increased utilization in TE based systems. However, the main challenge remains in striking the balance between the conflicting parameters; ZT and power factor, when designing and optimizing advanced TE materials. Hence more research is necessary to overcome this and other challenge so that the performance TE device can be improved further.

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A comprehensive review of thermoelectric technology: materials, applications, modelling and performance improvement

In recent years, advances in computational power and spatial data analysis (GIS, remote sensing, etc) have led to an increase in attempts to model the spread and behaviour of wildland fires across the landscape. This series of review papers endeavours to critically and comprehensively review all types of surface fire spread models developed since 1990. This paper reviews models of a physical or quasi-physical nature. These models are based on the fundamental chemistry and/or physics of combustion and fire spread. Other papers in the series review models of an empirical or quasi-empirical nature, and mathematical analogues and simulation models. Many models are extensions or refinements of models developed before 1990. Where this is the case, these models are also discussed but much less comprehensively.

A review of wildland fire spread modelling, 1990-present, 1: Physical and quasi-physical models

T governing equations for multidimensional radiating gas flow, in general, are of a complicated integrodifferential form. Thus, no reasonably simple solutions, valid for the whole range of optical thickness, exist for such problems at the present time. For the limiting cases of an optically thin or thick gas, the integrodifferential equations can be reduced to a system of differential equations, and earlier investigations" have been confined to these limits. For onedimensional flow problems, Vincenti and Baldwin suggested the use of an exponential function to approximate the integral term. By this approximation, they were able to obtain a system of purely differential equations that are valid for the whole range of optical thickness. Unfortunately, this technique is not directly applicable to multidimensional flow problems. A different scheme of approximation known as the moment method was first suggested by astrophysicists in problems of transfer of radiation in stars. It was subsequently highly developed by nuclear physicists in dealing with neutron transport problems. Using this scheme of approximation, Traugott and others were able to obtain a system of purely differential equations for one-dimensional flow problems that are valid throughout the whole range of optical thickness. It can be shown that the first approximation in this approach when applied to one-dimensional transfer problems is equivalent to the exponential approximation suggested by Vincenti and Baldwin. In the following, we will apply this technique to multidimensional radiating-gas-flow problems.

Two-dimensional radiating gas flow by a moment method

: The author first lists the hydrodynamic equations for the three-dimensional time-dependent flow. This is followed by a discussion of the approximate radiationtransport equations. Finally, the linearized equations for two-dimensional steady flow are obtained.

W. E. Ibele

Papers

Helium Transport Properties and the Lennard-Jones 6–9 Potential

Professor Richard J. Goldstein on his 60th birthday

Velocity profiles in two interdiffusing gas streams

Prandtl Number and Thermal Conductivity of Steam at One Atmosphere

Heat transfer—A review of 1968 literature