Thermo-mechanical analysis of a porous volumetric solar receiver subjected to concentrated solar radiation

Sharma, Sonika; Talukdar, Prabal

doi:10.1016/j.solener.2022.10.014

Cited by 16 publications

(4 citation statements)

References 46 publications

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“…Understanding the type of flow in macroporous channels is important for using standard similarity models and for understanding the heat and mass transfer processes in the interchannel macroporous medium. Most authors consider the motion in the macroporous medium of the channel type of the absorber of solar tower stations laminar due to low flow velocities [ 27 , 28 , 29 ]. Indeed, based on the analysis ( Figure 3 : Comparative analysis of the existing dependences of the Nusselt number on Reynolds for macroporous media), the fluid Reynolds values are too small to consider the flow as turbulent, but the study shows [ 30 ] vortices and micro convective reverse currents appear at the non-linear structure of the channel.…”

Section: Resultsmentioning

confidence: 99%

Analytical Determination of Nusselt Numbers for Convective Heat Transfer Coefficients in Channel Macroporous Absorbers

Cheilytko,

Schwarzbözl,

Broeske

2024

Materials

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This article introduces a novel analytical equation for computing the Nusselt number within the macroporous structures of channel absorbers utilized in high-temperature solar receivers. The equation incorporates heat and mass transfer processes occurring within boundary layers as fluid flows through complex-shaped macroporous absorber channels. The importance of accounting for the length of the thermodynamic boundary layer within channel-type macroporous media when calculating heat transfer coefficients using the Nusselt equation is demonstrated. By incorporating proposed indicators of porosity and flow characteristics, this method significantly enhances the accuracy of heat transfer coefficient calculations for such media. Discrepancies observed in existing calculation relationships and experiments are attributed to the omission of certain proposed values in the Nusselt number for macroporous media. To address this, empirical coefficients for the Nusselt number are derived using statistical methods. The resulting semi-empirical equation is applied to macroporous absorbers in solar receivers. The findings enable more accurate predictions of future absorber characteristics, enhancing their efficiency. The derived equation is successfully validated against numerical data across various geometric structures of absorbers in concentrated solar power plants.

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Section: Resultsmentioning

confidence: 99%

Analytical Determination of Nusselt Numbers for Convective Heat Transfer Coefficients in Channel Macroporous Absorbers

Cheilytko,

Schwarzbözl,

Broeske

2024

Materials

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show abstract

Section: Resultsmentioning

confidence: 99%

Analytical Determination of Nusselt Numbers for Convective Heat Transfer Coefficients in Macroporous Absorbers of High-Temperature Solar Receivers

Cheilytko,

Schwarzbözl,

Broeske

2023

Preprint

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The article presents a new analytical equation for calculating the Nu number in a macroporous structure of channel absorbers for high- temperature solar receivers. This equation is characterized by including the processes of heat and mass transfer in the boundary layers when the flow passes through a macroporous absorber channel of complex shape. The necessity of considering the length of the thermodynamic boundary layer in a macroporous medium of channel type, when calculating the heat transfer coefficient according to the Nusselt equation, is shown. Including the proposed indicators of porosity and flow characteristics in a macroporous channel significantly increases the accuracy of calculations of the heat transfer coefficient for macroporous channel media. The lack of consideration of certain of the proposed values in the Nusselt number for macroporous media explains the discrepancies in the existing calculation relationships and experiments. The empirical coefficients for the Nusselt number are proposed and obtained by the statistical method. The new semi-empirical equation obtained for macroporous channel media is applied to macroporous absorbers of solar receivers. The obtained results will help to predict the characteristics of future macroporous absorbers much more accurately than before to make them more efficient. The obtained equation for calculating the Nusselt number for channel-like macroporous absorbers has been successfully tested for the receiver of concentrated solar power plants with different geometric structure of the absorber.

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“…Hence, the flow of air in metal foam is laminar and incompressible. The volume difference between metal foam before heating and after heating due to solar intensities are ignored [41,42].…”

Section: Governing Equations and Turbulence Modellingmentioning

confidence: 99%

Numerical Study for Enhancement of Heat Transfer Using Discrete Metal Foam with Varying Thickness and Porosity in Solar Air Heater by LTNE Method

2022

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A two-dimensional rectangular domain is considered with a discrete arrangement at equal distances from copper metal foam in a solar air heater (SAH). The local thermal non-equilibrium model is used for the analysis of heat transfer in a single-pass rectangular channel of SAH for different mass flow rates ranging from 0.03 to 0.05 kg/s at 850 W/m2 heat flux. Three different pores per inch (PPI) and porosities of copper metal foam with three different discrete thicknesses at equal distances are studied numerically. This paper evaluates the performance of SAH with 10 PPI 0.8769 porosity, 20 PPI 0.8567 porosity, and 30 PPI 0.92 porosity at 22 mm, 44 mm, and 88 mm thicknesses. The Nusselt number for 22 mm, 44 mm, and 88 mm thicknesses is 157.64%, 183.31%, and 218.60%, respectively, higher than the empty channel. The performance factor for 22 mm thick metal foam is 5.02% and 16.61% higher than for 44 mm and 88 mm thick metal foam, respectively. Hence, it is found that metal foam can be an excellent option for heat transfer enhancement in SAH, if it is designed properly.

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Thermo-mechanical analysis of a porous volumetric solar receiver subjected to concentrated solar radiation

Cited by 16 publications

References 46 publications

Analytical Determination of Nusselt Numbers for Convective Heat Transfer Coefficients in Channel Macroporous Absorbers

Analytical Determination of Nusselt Numbers for Convective Heat Transfer Coefficients in Channel Macroporous Absorbers

Analytical Determination of Nusselt Numbers for Convective Heat Transfer Coefficients in Macroporous Absorbers of High-Temperature Solar Receivers

Numerical Study for Enhancement of Heat Transfer Using Discrete Metal Foam with Varying Thickness and Porosity in Solar Air Heater by LTNE Method

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