Numerical analyses of three-dimensional fixed reaction bed for thermochemical energy storage

Ranjha, Qasim A.; Öztekin, Alparslan

doi:10.1016/j.renene.2017.04.062

Cited by 58 publications

(15 citation statements)

References 32 publications

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“…Heat exchanger sizing software such as COMSOL Multiphysics offers a high range of functionality for optimal sizing of the heat exchangers. Moreover, many recent works in thermochemical heat storage have used this software with very satisfactory results [137,138]. The innovative aspect of heat exchangers used in thermochemical heat storage is that most of them are heat exchangers involving a solid and a fluid.…”

Section: Tces Reactor Sizing Analysis Criteria and Assumptionsmentioning

confidence: 99%

Recent Status and Prospects on Thermochemical Heat Storage Processes and Applications

Gbenou

Fopah-Lele

Wang

2021

Entropy

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Recent contributions to thermochemical heat storage (TCHS) technology have been reviewed and have revealed that there are four main branches whose mastery could significantly contribute to the field. These are the control of the processes to store or release heat, a perfect understanding and designing of the materials used for each storage process, the good sizing of the reactor, and the mastery of the whole system connected to design an efficient system. The above-mentioned fields constitute a very complex area of investigation, and most of the works focus on one of the branches to deepen their research. For this purpose, significant contributions have been and continue to be made. However, the technology is still not mature, and, up to now, no definitive, efficient, autonomous, practical, and commercial TCHS device is available. This paper highlights several issues that impede the maturity of the technology. These are the limited number of research works dedicated to the topic, the simulation results that are too illusory and impossible to implement in real prototypes, the incomplete analysis of the proposed works (simulation works without experimentation or experimentations without prior simulation study), and the endless problem of heat and mass transfer limitation. This paper provides insights and recommendations to better analyze and solve the problems that still challenge the technology.

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Section: Tces Reactor Sizing Analysis Criteria and Assumptionsmentioning

confidence: 99%

Recent Status and Prospects on Thermochemical Heat Storage Processes and Applications

Gbenou

Fopah-Lele

Wang

2021

Entropy

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“…A comprehensive model for a permeated fixed bed was introduced by Nagel et al [25], and several simplified models were applied to this reactor type (e.g., [26,27]). For an indirectly heated fixed bed, some models with similar governing equations were utilized (e.g., [28][29][30]). However, few numerical analyses addressed the dehydration at low steam pressures, and due to the lack of experimental data, the numerical results have only been compared to single measurements.…”

Section: Introductionmentioning

confidence: 99%

“…No strong three-dimensional effects occur, and a two-dimensional rotation symmetric model is sufficient (based on [28]).…”

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confidence: 99%

Experimental and Numerical Investigation of the Dehydration of Ca(OH)2 at Low Steam Pressures

et al. 2022

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The CaO/Ca(OH)2 system can be the basis for cost-efficient long-term energy storage, as the chemically stored energy is not affected by heat losses, and the raw material is cheap and abundantly available. While the hydration (thermal discharge) has already been addressed by several studies, for the dehydration (thermal charge) at low partial steam pressures, there is a lack of numerical studies validated at different conditions and operation modes. However, the operation at low steam pressures is important, as it decreases the dehydration temperature, which can enable the use of waste heat. Even if higher charging temperatures are available, for example by incorporating electrical energy, the reaction rate can be increased by lowering the steam pressure. At low pressures and temperatures, the limiting steps in a reactor might change compared to previous studies. In particular, the reaction kinetics might become limiting due to a decreased reaction rate at lower temperatures, or the reduced steam density at low pressures could result in high velocities, causing a gas transport limitation. Therefore, we conducted new measurements with a thermogravimetric analyzer only for the specific steam partial pressure range between 0.8 and 5.5 kPa. Based on these measurements, we derived a new mathematical fit for the reaction rate for the temperature range between 375 and 440 °C. Additionally, we performed experiments in an indirectly heated fixed bed reactor with two different operation modes in a pressure range between 2.8 and 4.8 kPa and set up a numerical model. The numerical results show that the model appropriately describes the reactor behavior and is validated within the measurement uncertainty. Moreover, our study revealed an important impact of the operation condition itself: the permeability of the reactive bulk is significantly increased if the dehydration is initiated by a rapid pressure reduction compared to an isobaric dehydration by a temperature increase. We conclude that the pressure reduction leads to structural changes in the bulk, such as channeling, which enhances the gas transport. This finding could reduce the complexity of future reactor designs. Finally, the presented model can assist the design of thermochemical reactors in the validated pressure and temperature range.

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“…Zhou et al [18] [19,20]. Ranjha and Oztekin [21] performed a numerical analysis of a three-dimensional bed with Ca(OH) 2 /CaO as the reaction pair. The results of the study provide detailed insight into the heat release processes occurring in a fixed bed of Ca(OH) 2 /CaO reaction pair.…”

Section: Introductionmentioning

confidence: 99%

Performance analysis of a K2CO3-based thermochemical energy storage system using a honeycomb structured heat exchanger

Kant

Shukla

Smeulders

et al. 2021

Journal of Energy Storage

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Numerical analyses of three-dimensional fixed reaction bed for thermochemical energy storage

Cited by 58 publications

References 32 publications

Recent Status and Prospects on Thermochemical Heat Storage Processes and Applications

Recent Status and Prospects on Thermochemical Heat Storage Processes and Applications

Experimental and Numerical Investigation of the Dehydration of Ca(OH)2 at Low Steam Pressures

Performance analysis of a K2CO3-based thermochemical energy storage system using a honeycomb structured heat exchanger

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