Enhanced Thermal Properties of PCM Based Nanofluid for Solar Thermal Energy Storage

2010 ◽  
Author(s):  
Donghyun Shin ◽  
Debjyoti Banerjee
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Transport Properties ◽  
Experimental Studies ◽  
Thermal Storage ◽  
Nano Particles ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Heat Diffusivity ◽  
Solar Thermal Applications

Nanofluids are synthesized by doping solvents with nano-particles at minute concentrations (typically less than 1 percentage by volume). Experimental studies have shown that nano-particles can dramatically enhance thermal conductivity of various liquid solvents. This is also associated with enhancement of other transport properties (e.g., viscosity, specific heat, diffusivity, etc.). Hence, nanofluids are attractive materials for solar thermal applications. The objective of this study is to investigate the optimum performance of various nanofluids for solar thermal storage applications. Dimensional analyses and similitude techniques will be used to theoretically estimate the enhancement of transport properties of various nanofluids to predict their efficacy for solar thermal storage applications.

Investigation of Nanofluids for Solar Thermal Storage Applications

2009 ◽  
Author(s):  
Donghyun Shin ◽  
Debjyoti Banerjee
Keyword(s):  
Thermal Conductivity ◽  
Specific Heat ◽  
Transport Properties ◽  
Experimental Studies ◽  
Thermal Storage ◽  
Nano Particles ◽  
Solar Thermal ◽  
Optimum Performance ◽  
Solar Thermal Applications

Nanofluids are synthesized by doping solvents with nano-particles at minute concentrations (typically less than 1 percentage by volume). Experimental studies have shown that nano-particles can dramatically enhance the specific heat of various liquid solvents. This is also associated with enhancement of other transport properties (e.g., viscosity, thermal conductivity, diffusivity, etc.). Hence, nanofluids are attractive materials for solar thermal applications. The objective of this study is to investigate the optimum performance of various nanofluids for solar thermal storage applications. Dimensional analyses and similitude techniques will be used to theoretically estimate the enhancement of transport properties of various nanofluids to predict their efficacy for solar thermal storage applications.

Optimization of Pigmented Coatings for Concentrating Solar Thermal Applications

2011 ◽  
Author(s):  
Refet A. Yalcin ◽  
Hakan Ertu¨rk
Keyword(s):  
Simplex Algorithm ◽  
Nano Particles ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Spectrally Selective ◽  
Design Variables ◽  
Scattering Effects ◽  
Spectral Emittance ◽  
Solar Thermal Applications ◽  
Pigmented Coatings

Spectrally selective coatings are used in absorbers of solar collectors to maximize efficiency of solar thermal energy systems. Desired coating should have high absorptance at solar wavelengths and low emittance at the wavelengths where absorber emits heat. This study focuses on pigmented coatings that consist of a binder and uniformly distributed nano-particles known as pigments that exhibit the desired spectrally selective behavior. Radiative behavior of coatings depend on coating thickness, pigment size, concentration, and the optical properties of binder and pigment materials. In order to understand the effect of these parameters, a radiative model of the pigmented coatings is developed using Lorentz-Mie theory in conjunction with Hartel theory to incorporate the multiple scattering effects. Through the solution of the radiative transfer equation by the four flux method, spectral emittance is predicted. Design of such a coating is formulated as an inverse problem of estimating design variables yielding the desired spectral emittance of the ideal coating. The nonlinear problem is solved by optimization applying two algorithms for the solution. While both algorithms are capable of providing the same solution, the convergence of Quasi Newton method is found to be superior to that of Nelder Mead simplex algorithm.

scholarly journals Thermal Properties of Foundry Mould Made of Used Green Sand

2016 ◽  
Vol 16 (1) ◽  
pp. 29-32
Author(s):  
P.K. Krajewski ◽  
G. Piwowarski ◽  
J. Buraś
Keyword(s):  
Thermal Conductivity ◽  
Temperature Field ◽  
Thermal Properties ◽  
Mould Temperature ◽  
Green Sand ◽  
Foundry Sand ◽  
Temperature Range ◽  
Heat Diffusivity ◽  
Water Vaporization ◽  
Moulding Sand

Abstract The paper presents results of measuring heat diffusivity and thermal conductivity coefficients of used green foundry sand in temperature range ambient − 600 °C. During the experiments a technical purity Cu plate was cast into the green-sand moulds. Basing on measurements of the mould temperature field during the solidification of the casting, the temperature relationships of the measured properties were evaluated. It was confirmed that the obtained relationships are complex and that water vaporization strongly influences thermal conductivity of the moulding sand in the first period of the mould heating by the poured and solidified casting.

scholarly journals Low-Cost High Energy Density Material for Solar Thermal Heat Storage

2020 ◽  
Vol 3 (2) ◽  
pp. 46-56
Author(s):  
Rebhi Damseh
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Energy Density ◽  
Heat Storage ◽  
Low Cost ◽  
High Energy ◽  
Solar Thermal ◽  
Energy Storage Density ◽  
Solar Thermal Energy ◽  
Storage Density

A low-cost and enhanced thermal properties composite material for sensible heat storage in solar thermal energy storage applications is introduced. The proposed material is produced primarily for small scale solar thermal applications. However, it can be utilized for large scale solar thermal plants. The material has the advantages of high thermal conductivity and large energy storage density. The introduced material is composed of a mixture of cement and cast-iron particles. To obtain an optimal mixture, different samples of the material are prepared with different ratios of the cement-iron weights. The thermal conductivity of the produced samples is measured by using the linear heat conduction method. The specific heat capacity of the produced mixtures is calculated by using the Rule of the mixture. The obtained results show that the introduced material has a significant enhancement in thermal conductivity. Where, thermal conductivity as high as ~6.0 W/m.K and energy storage density as high as ~788 Joule/cm3 are achieved. The estimated volume energy density is ~89% higher than that of water. The produced material has the advantage of high energy volume density, being unhazardous, chemically stable, eco-friendly, easy to fabricate, and integrate with solar thermal energy systems and is a low-cost material.

Effect of Ni in new skutterudite compounds CaxCo4Sb12

2003 ◽  
Vol 793 ◽  
Author(s):  
Matthieu Puyet ◽  
Bertrand Lenoir ◽  
Anne Dauscher ◽  
Hubert Scherrer ◽  
Moukrane Dehmas ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Thermal Properties ◽  
Beneficial Effect ◽  
Transport Properties ◽  
Figure Of Merit ◽  
Positive Influence ◽  
Temperature Range ◽  
Dimensionless Figure Of Merit ◽  
Ni Substitution

ABSTRACTThe transport properties of the partially filled CaxCo4-yNiySb12 skutterudite compounds have been investigated in the 300 – 800 K temperature range. We underline the positive influence of the Ni substitution on the electrical resistivity and thermopower while the thermal properties – thermal conductivity – remains almost unaffected. These results suggest again a beneficial effect of Ni atoms on the dimensionless figure of merit in CoSb3 based compounds.

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