Analysis of Transient Heat Transfer in a Thermal Energy Storage Module

Kuravi, Sarada; Trahan, Jamie; Rahman, Muhammad M.; Goswami, D. Yogi; Stefanakos, Elias K.

doi:10.1115/imece2010-40773

Cited by 7 publications

(3 citation statements)

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“…The solidification time indeed shows a one fold increase when Re is reduced from 2000 to 500 as depicted in figure 7.right. A similar result has been also found by Kuravi and co-workers[36]. As obvious the same large impact has been found when correlating HTF Reynolds number and position of the solidification front.…”

supporting

confidence: 89%

Numerical analysis of a medium scale latent energy storage unit for district heating systems

Colella

Sciacovelli

Verda

2012

Energy

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The present paper describes the application of computational fluid-dynamics (CFD) to the design and characterization of a medium scale energy storage unit for district heating systems. The shell-and-tube LHTES unit contains a technical grade paraffin (RT100) and uses water as heat transfer fluid (HTF). The system has been designed to transfer heat from the primary to the secondary heat district heating networks. After an initial description of the LHTES unit and a wide literature overview on the subject, the paper discusses the need for thermal enhancement to improve the thermal conductivity of the phase change material (PCM). A solution based on a paraffin-graphite composite with a 15% graphite volume fraction has been found to be well performing in this particular application. Several operating scenarios characterized by heat requests ranging between 130kW and 400kW have been explored and the main outputs presented as function of Re and St numbers. The time-wise variations of other significant quantities such as liquid fraction, sensible and latent energy content, HFT outlet temperature and heat fluxes have been also presented and discussed. A final discussion on the possible system configurations shows that in comparison to traditional water storage systems for district heating, LHTES systems provide, depending on the chose alternative, higher energy storage densities.

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supporting

confidence: 89%

Numerical analysis of a medium scale latent energy storage unit for district heating systems

Colella

Sciacovelli

Verda

2012

Energy

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“…Such an assumption was confirmed in Refs. [24,25], since discharge process of LHTES units is dominated by heat conduction. Natural convection only exists at the beginning of the process.…”

Section: Mathematical Model 21 Governing Equationsmentioning

confidence: 99%

Second Law Optimization of a PCM Based Latent Heat Thermal Energy Storage System with Tree Shaped Fins

Sciacovelli¹,

Guelpa²,

Verda³

2014

Int. J. Thermo

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The aim of this paper is to perform a thermodynamic optimization of a Y shaped fin design used to improve thermal performance of a latent heat thermal energy storage (LHTES) unit. The investigation is performed through a CFD model that takes into account the thermal behavior of the system. Temperature and phase fields are obtained to characterize the heat transfer phenomenon and to compute the entropy generation rate within the system. Global entropy generation and energy flux are adopted as objective functions to perform a shape optimization of the Y shaped fins with angles and branches lengths that can vary freely. The optimization results indicate that a higher energy transfer is achieved by a fin configuration with long secondary branches with an orientation angle of 30°. This design allows one to increase PCM solidification rate of about 30%. Furthermore, Y-shaped fins allow to increase the exergy flux released by the PCM, thus Second-law efficiency is not affected although entropy generation increases. This work represents the first detailed thermodynamic optimization of a system involving an unsteady process. This aspect is particularly important since a clear tendency of many energy systems is toward transient operation, thus design optimization methods should evolve accordingly.

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“…Solar stills can be classified into active and passive solar stills. Many papers have studied more specific characteristics of solar stills with various configurations, hemispherical solar stills [4], spherical solar still [5], pyramidal solar still [6], double-basin solar still [7][8][9][10][11], vacuum solar still [12], compound parabolic concentrator (CPC) solar still [5], wick type solar still [13], triple basin solar still [14], multiple basin solar still [15,16], inverted absorber solar still [17][18][19][20], tubular solar stills [20][21][22][23], solar still coupled with solar collectors, and thermal storage [24][25][26][27][28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

A Thermal Model for Predicting the Performance of a Solar Still with Fresnel Lens

Johnson

Park

et al. 2019

Water

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This study presents a theoretical model to simulate the temperatures and productivity of a single-slope, single-basin solar still when an external solar enhancement is used. Experiments were performed in the New Mexico region (32.3199° N, 106.7637° W) to validate the numerical model. A point focusing Fresnel lens was used in the experiments to enhance the solar input. It was found that a significant rise in the productivity of the still was achieved with the Fresnel lens. Parametric study by varying the water depth showed the Fresnel lens was more effective for larger water depths. In addition, the Fresnel lens can aid in improving the overall efficiency of the solar still.

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Analysis of Transient Heat Transfer in a Thermal Energy Storage Module

Cited by 7 publications

References 0 publications

Numerical analysis of a medium scale latent energy storage unit for district heating systems

Numerical analysis of a medium scale latent energy storage unit for district heating systems

Second Law Optimization of a PCM Based Latent Heat Thermal Energy Storage System with Tree Shaped Fins

A Thermal Model for Predicting the Performance of a Solar Still with Fresnel Lens

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