Use of partial load operating conditions for latent thermal energy storage management

Gasia, Jaume; Gracia, Álvaro de; Peiró, Gerard; Arena, Simone; Cau, Giorgio; Cabeza, Luisa F.

doi:10.1016/j.apenergy.2018.02.061

Cited by 29 publications

(13 citation statements)

References 19 publications

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“…Compared to non-finned latent heat TES where the power rate for discharging is an order of magnitude lower at the end of discharging (e.g. [37] ), the heat transfer enhancement with fins is remarkable.…”

Section: Resultsmentioning

confidence: 92%

“…Similar studies, but on a lower temperature level with a different storage type and PCM are the experimental studies by Gasia et al. [37] , which deal with partial load operation modes. In [42] storage times are added to the research as an additional complexity factor.…”

Section: Introductionmentioning

confidence: 80%

“…The amount of stored energy is an essential parameter for energy storage systems in general. The ratio of stored energy to the total amount of storable energy is called “ratio of accumulated energy” [37] or “ratio of energy” [44] . The term “state of charge” appeared more suitable and is based on the definitions in [40] .…”

Section: Theorymentioning

confidence: 99%

“…The so called state of charge (

) is defined in several publications. Common synonyms are “ratio of accumulated energy (RAE)” [37] and “liquid fraction” [38] . A precise definition of the

for the present investigation is provided in the theory chapter.…”

Section: Introductionmentioning

confidence: 99%

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Partial cycle operation of latent heat storage with finned tubes

et al. 2020

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This work examines a high temperature latent heat storage system, which could find use in future concentrated solar power and other combined heat and power plants. In contrast to lab-based fully charged or totally discharged states, partial load states will be the principal operation states in real-world applications. Hence, a closer look on the partial load states and the effective power rates are worthwhile for a successful implementation of this storage type. A vertical finned shell and tube heat exchanger pipe with a combination of transversal and longitudinal fins is applied. Sodium nitrate with a melting temperature of 306 is used as phase change material and thermal oil serves as heat transfer fluid. Temperatures in the storage and the heat transfer fluid as well as the mass flow are measured for data analysis. The state of charge formulation is based on an enthalpy distribution function, where the latent heat of fusion is spread over a specific temperature range. The data show consistently high power rates for all partial load cycles at any state of charge. The mean power rate for charging is 6.78 kW with an 95.45 % confidence interval of 1.14 kW for all cycles. The discharging power rate is −5.72 kW with a 95.45 % confidence interval of 1.36 kW for all cycles. The lowest power rate is measured for the full cycle at the end of charging/discharging. It is caused by a narrow volume, which is not penetrated by fins, near the perimeter of the cylindrical heat exchanger. The state of charge formulation correlates with the storage capacity and enables state of charge based cycling. With the energy balance of the storage, the data validity is proven and further storage parameters are determined. The energy density is as high as 110 kW h m −3 and a power rate of 2.28 kW m −1 for the finned tube is confirmed. These values are highly promising for further development and application of latent heat storage systems.

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Section: Resultsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 80%

Section: Theorymentioning

confidence: 99%

“…The so called state of charge (

) is defined in several publications. Common synonyms are “ratio of accumulated energy (RAE)” [37] and “liquid fraction” [38] . A precise definition of the

for the present investigation is provided in the theory chapter.…”

Section: Introductionmentioning

confidence: 99%

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Partial cycle operation of latent heat storage with finned tubes

et al. 2020

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“…The latent heat TES technology is evaluated in a 0.154 m 3 storage tank based on the shell-andtube heat exchanger concept which is connected to a heat source and a heat sink simulating the waste heat recovery of an industrial process [39]. The material used is 99.5 kg of high density polyethylene (HDPE).…”

Section: Latent Heat Tesmentioning

confidence: 99%

Evaluation of energy density as performance indicator for thermal energy storage at material and system levels

et al. 2019

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The increase of the capacity factor of thermal processes which use renewable energies is closely linked to the implementation of thermal energy storage (TES) systems. Currently, TES systems can be classified depending on the technology for storing thermal: sensible heat, latent heat, and sorption and chemical reactions (usually known as thermochemical energy storage). However, there is no standardized procedure for the evaluation of such technologies, and therefore the development of performance indicators which suit the requisites of the final users becomes an important goal. In the present paper, the authors identified the energy density as an important performance indicator for TES, and evaluated it at both material and system levels. This approach is afterwards applied to prototypes covering the three TES technologies: a two-tank molten salts sensible storage system, a shell-and-tube latent heat storage system, and a magnesium oxide and water chemical storage system. The evaluation of the energy density highlighted the difference of its value at the material value, which presents a theoretical maximum, and the results at system level, which considers all the parts required for operating the TES, and thus presents a significantly lower value. Moreover, the proposed approach captured the effect of the complexity and overall size of the system, showing the relevance of this performance indicator for evaluating technologies for applications in which volume is a limiting parameter.

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Analysis of the Thermal Management of a High‐Temperature Methanol Fuel Cell Using a Latent Heat Storage

et al. 2021

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Waste heat from industrial applications offers a high but mostly unused potential due to the time differences between its generation and possible consumption. By using waste heat, the energy efficiency can be increased and therefore, the overall costs and emissions can be reduced. This work shows the feasibility of increasing the energy efficiency of a high‐temperature methanol fuel cell using a latent heat storage with the help of full‐scale experiments. The fuel cell needs to be preheated for start up to reach its operation temperature. During operation, heat is generated at a temperature of 433 K and the system needs to be air‐cooled to maintain its temperature. Instead of cooling the fuel cell with air and losing the heat to the environment, the waste heat is now stored in a latent heat storage to later be used for preheating the fuel cell. Different experiments are conducted to find the optimum operation point of the latent heat storage in combination with the fuel cell. The aging and the cycling stability of high density polyethylene, which is used as phase change material in the latent heat storage, is monitored as well as the mechanical stability of the system.

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Use of partial load operating conditions for latent thermal energy storage management

Abstract: Està subjecte a una llicència de Reconeixement-NoComercial-SenseObraDerivada 4.

Cited by 29 publications

References 19 publications

Partial cycle operation of latent heat storage with finned tubes

Partial cycle operation of latent heat storage with finned tubes

Evaluation of energy density as performance indicator for thermal energy storage at material and system levels

Analysis of the Thermal Management of a High‐Temperature Methanol Fuel Cell Using a Latent Heat Storage

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