The Experts below are selected from a list of 2340 Experts worldwide ranked by ideXlab platform
Juan M Coronado - One of the best experts on this subject based on the ideXlab platform.
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impact of la doping on the Thermochemical Heat Storage properties of camno3 δ
Journal of energy storage, 2021Co-Authors: Juan M Coronado, Emanuela Mastronardo, Xin Qian, Sossina M HaileAbstract:Abstract Recently, CaMnO3 has been proposed as a promising candidate for high temperature Thermochemical Heat Storage. The material reversibly releases oxygen in response to changes in oxygen partial pressure (pO2) in the temperature range (800-1000°C) suitable for Concentrated Solar Power (CSP) plants. However, it undergoes decomposition at pO2
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assessing cr incorporation in mn2o3 mn3o4 redox materials for Thermochemical Heat Storage applications
Journal of energy storage, 2021Co-Authors: Alfonso J Carrillo, Patricia Pizarro, Juan M CoronadoAbstract:Abstract Widening the use of renewable sources requires more efficient energy Storage systems to overcome the inherent intermittence of solar energy. In this respect, thermal energy Storage coupled to concentrated solar power represents an inexpensive technology to achieve that goal. In particular, the use of reversible Thermochemical reactions is promising due to a higher energy Storage density if compared with commercial sensible Heat Storage on molten salts. However, some of these systems that rely on gas-solid reactions can suffer a cycle-to-cycle loss of activity due to slow kinetics and materials degradation, which is detrimental for its potential future commercialization. In this work, we have assessed the incorporation of Cr cations in the redox couple Mn2O3/Mn3O4, as a way to stabilize the multi-cyclic activity over prolonged operation at high temperatures (650-1000 °C). Reduction has been studied with in situ XRD and kinetic analyses, which confirm that Cr incorporation shifts the reaction towards high temperatures. Long term redox cycling tests confirm that 5% Cr incorporation helps to stabilize the redox activity of Mn2O3/Mn3O4.
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the favourable thermodynamic properties of fe doped camno3 for Thermochemical Heat Storage
Journal of Materials Chemistry, 2020Co-Authors: Juan M Coronado, Emanuela Mastronardo, Xin Qian, Sossina M HaileAbstract:The CaMnO3 oxide can reversibly release oxygen over a relatively wide range of temperatures and oxygen partial pressures (pO2) and is thus a promising candidate for Thermochemical Heat Storage in Concentrated Solar Power (CSP) plants. Moreover, it is composed of earth-abundant, inexpensive and non-toxic elements and exhibits a high-energy Storage density, which are desirable characteristics for decreasing the deployment costs of the system. However, it undergoes decomposition at pO2 ≤ 0.008 atm and temperature ≥ 1100 °C. Here the possibility of overcoming this limitation and extending the operating temperature range by B-site doping with Fe (CaFexMn1−xO3−δ0) is explored. Two doping levels are investigated, x = 0.1 and 0.3. The enthalpy of reduction was determined from a measurement of continuous equilibrium non-stoichiometry curves (δ, T) at several pO2, enabling an evaluation of the Heat Storage capacity with high accuracy over widely ranging oxygen non-stoichiometry. Introduction of 0.1 Fe (CaFe0.1Mn0.9O3−δ0) prevented CaMnO3 decomposition up to 1200 °C at pO2 = 0.008 atm, thus widening the operating temperature range and the oxygen reduction extent. The increase in the accessible nonstoichiometry translates into an increase in the Heat Storage capacity (QM (kJ molABO3−1)) from ∼272 kJ kgABO3−1 in CaMnO3 to ∼344 kJ kgABO3−1 in CaFe0.1Mn0.9O3−δ0. While even larger changes in oxygen content were accessible in CaFe0.3Mn0.7O3−δ0, the oxidation state changes are accompanied by a lower enthalpy of reduction, resulting in a diminished Heat Storage capacity of ∼221 kJ kgABO3−1.
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fe doped camno3 for Thermochemical Heat Storage application
24th SolarPACES International Conference on Concentrating Solar Power and Chemical Energy Systems SolarPACES 2018, 2019Co-Authors: Juan M Coronado, Emanuela Mastronardo, Xin Qian, Sossina M HaileAbstract:CaMnO3 oxide can be considered a promising candidate for high temperature Thermochemical Heat Storage, since it is able to release oxygen in a wide temperature range (800-1000 °C) at different oxygen partial pressures (pO2) suitable for Concentrated Solar Power (CSP) plants. Moreover, it is composed of earth abundant, inexpensive, non-toxic elements. However, it undergoes decomposition at pO2<0.01 atm and at temperature above 1100 °C. In order to overcome this limitation and to extent the operating temperature range, in this study B-site doping with Fe was used as approach for preventing decomposition. The reaction enthalpy was measured through equilibrium non-stoichiometry curves so that the Heat Storage capacity could be evaluated. It was demonstrated that Fe-doping prevented CaMnO3 decomposition up to 1200 °C at pO2=0.008 thus widening the operating temperature range and the oxygen reduction extent. In addition, the Heat Storage capacity (ΔH (kJ/molABO3)) of Fe-CaMnO3 (∼324 kJ/kgABO3) is remarkably higher than that of the un-doped CaMnO3 (∼250 kJ/kgABO3).
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solar energy on demand a review on high temperature Thermochemical Heat Storage systems and materials
Chemical Reviews, 2019Co-Authors: Alfonso J Carrillo, Jose Gonzalezaguilar, Manuel Romero, Juan M CoronadoAbstract:Among renewable energies, wind and solar are inherently intermittent and therefore both require efficient energy Storage systems to facilitate a round-the-clock electricity production at a global scale. In this context, concentrated solar power (CSP) stands out among other sustainable technologies because it offers the interesting possibility of storing energy collected from the sun as Heat by sensible, latent, or Thermochemical means. Accordingly, continuous electricity generation in the power block is possible even during off-sun periods, providing CSP plants with a remarkable dispatchability. Sensible Heat Storage has been already incorporated to commercial CSP plants. However, because of its potentially higher energy Storage density, Thermochemical Heat Storage (TCS) systems emerge as an attractive alternative for the design of next-generation power plants, which are expected to operate at higher temperatures. Through these systems, thermal energy is used to drive endothermic chemical reactions, which...
Athanasios G. Konstandopoulos - One of the best experts on this subject based on the ideXlab platform.
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shortlisting of composite cao based structured bodies suitable for Thermochemical Heat Storage with the cao ca oh 2 reaction scheme
Energy & Fuels, 2017Co-Authors: Kyriaki G. Sakellariou, George Karagiannakis, Nikolaos I Tsongidis, Athanasios G. KonstandopoulosAbstract:The CaO/Ca(OH)2 couple is a promising candidate for Thermochemical Heat Storage applications based on the cyclic hydration/dehydration reaction scheme at temperatures between 400 and 550 °C. The fragmentation of CaO particles during multicyclic operation is an acknowledged phenomenon leading to significant challenges regarding particle reactor bed operation. With the aim to eliminate or significantly mitigate this phenomenon, the current work describes the development of composite CaO-based compositions with enhanced structural stability over multiple hydration/dehydration cycles. The preparation of composite materials was based on the utilization of kaolinite as binder, added at a weight percentage of 25% in natural limestone powder in order to ensure improved mechanical properties of active particles. Nearly spherical structured formulations were manufactured via a simple preparation method based on two solid mixing techniques. A parametric study examined the effect of different parameters (such as CaCO...
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cobalt oxide based honeycombs as reactors Heat exchangers for redox Thermochemical Heat Storage in future csp plants
Energy Procedia, 2015Co-Authors: Chrysoula Pagkoura, George Karagiannakis, A Zygogianni, Souzana Lorentzou, Athanasios G. KonstandopoulosAbstract:Abstract The Co 3 O 4 /CoO redox system has been recently proposed and is currently under consideration by several research groups as a promising Thermochemical Heat Storage (THS) scheme to be coupled with high temperature Concentrated Solar Power plants. The present work is an investigation of cobalt oxide based honeycomb structures as candidate reactors/Heat exchangers in relevant compact and efficient THS systems. The formulations studied included extruded bodies from pure cobalt oxide and two different cobalt oxide/alumina composites (i.e. 95/5 wt% and 90/10 wt%) as well as cobalt oxide-coated cordierite honeycombs with two different loadings (i.e. 28% and 65%). The structures were evaluated with respect to their redox performance in the course of 5 successive cycles in the temperature window of 800-1000 o C and under air flow. Based on measured oxygen evolution profiles, honeycombs from pure cobalt oxide and cobalt oxide-coated cordierites exhibited very similar normalized (i.e. μmol O 2 /g Co 3 O 4 ) redox performance. On the other hand, the addition of alumina had a moderately negative effect on normalized redox performance versus the two aforementioned formulations but contributed to the substantial increase of the honeycombs structural stability when compared to the extruded pure cobalt oxide monolith. The particular finding was based on performing, in a separate experimental setup, 10 redox cycles under idealized (i.e. no imposed loads) conditions. Pre- (i.e. fresh/calcined) and post-characterization (i.e. after 10 redox cycles) of extruded structures via mercury porosimetry revealed measurable decrease of bulk density and increase of mean pore size, indicating a net structure expansion/‘swelling’ effect.
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Calcium oxide based materials for Thermochemical Heat Storage in concentrated solar power plants
Solar Energy, 2015Co-Authors: Kyriaki G. Sakellariou, George Karagiannakis, Yolanda A. Criado, Athanasios G. KonstandopoulosAbstract:The present study relates to the preparation of mixed calcium oxide-alumina compositions as candidate materials for a cyclic Thermochemical hydration-dehydration scheme at moderate to high temperatures (e.g. 400-600. ??C) that can offer the possibility of short and long term energy Storage, particularly suitable for concentrated solar power installations. The synthesized materials were assessed in terms of their cyclic hydration-dehydration performance in the temperature range of 200-550. ??C. Acknowledging the fact that the particular Thermochemical scheme has been identified to result in substantial cycle-to-cycle fragmentation of pure CaO particles which is detrimental to particle reactor bed concepts, one of the main purposes of using Al as additive is related to materials structural enhancement. To this respect, preliminary studies related to macro-structural integrity assessment were also conducted. In addition, the performance of synthesized material is compared to the one of natural lime (benchmark material). The additive content spanned over a wide range of Ca/Al molar ratios, namely from 95/5 to 52/48, while two different calcium oxide precursors, i.e. calcium nitrate and calcium acetate, were employed. Fresh and hydrated compositions were characterized in-detail with respect to their physicochemical properties in order to correlate different behaviors with certain attributes of the materials. Synthetic materials, both calcium nitrate and calcium acetate derived, favored the formation of Ca/Al mixed phases. The latter led to materials with higher surface areas and, for a given Ca/Al ratio, resulted to higher hydration/dehydration performance. Mixed oxides, although capable of being hydrated at ambient temperature, did not participate in the reaction scheme at temperatures ???200. ??C and thus presence of such phases resulted in considerable decrease of hydration/dehydration capacity versus the one of natural lime. On the other hand, the presence of such mixed compositions improved, albeit not dramatically, macro-structural integrity. A relatively good combination of hydration-dehydration performance with better-than-natural lime structural integrity was achieved for the mixed materials with a Ca/Al molar ratio equal to 89/11 and 81/19 molar ratio. The Ca-precursor used in these materials slightly affected their cyclic performance with the ex-CaN ones presenting better behavior.
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cobalt oxide based structured bodies as redox Thermochemical Heat Storage medium for future csp plants
Solar Energy, 2014Co-Authors: Chrysoula Pagkoura, George Karagiannakis, Athanasios G. Konstandopoulos, A Zygogianni, Souzana Lorentzou, Margaritis Kostoglou, Michael Rattenburry, James W WoodheadAbstract:Abstract The present work is an investigation of the redox performance of several cobalt oxide based compositions, as candidate materials for energy Storage in future concentrated solar power plants. To this respect, various commercial and in-house synthesized grades were evaluated in the form of small structured perforated monolithic bodies (flow-through pellets) and assessed in terms of their capability to perform reversible cyclic reduction–oxidation reactions under air flow in the temperature range of 800–1000 °C. The compositions studied involved pure cobalt oxide as well as composites of cobalt oxide with ceria, zirconia, alumina, iron oxide, silicon carbide and manganese oxide. The main criterion for the evaluation of compositions considered was a combination of high redox reaction extent with good thermo-mechanical stability of fabricated structured bodies. Among the materials studied and based on this criterion, the most promising ones were the cobalt oxide–alumina and cobalt oxide–iron oxide composites. Although pure cobalt oxide, and especially one grade synthesized in the lab, exhibited the highest redox performance, the respective shaped structures did not manage to retain their macro-structural integrity in the course of 10 redox cycles. Moreover, it was found that, under certain conditions, the addition of ceria improved redox reaction kinetics, while total performance of cobalt oxide was not affected. However, the structural stability of cobalt oxide–ceria pellets was also problematic. It was also demonstrated that by varying the second oxide, the start-of-reduction/oxidation temperatures of cobalt oxide can be significantly altered. A preliminary simplified kinetic model was developed and its good agreement with pure cobalt oxide redox experimental data was also demonstrated. Post-characterization of used structured bodies confirmed the experimental findings of redox performance measurements and, to some extent, provided explanations regarding the main phenomena involved upon cyclic operation of different compositions employed.
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monolithic ceramic redox materials for Thermochemical Heat Storage applications in csp plants
Energy Procedia, 2014Co-Authors: George Karagiannakis, Chrysoula Pagkoura, A Zygogianni, Souzana Lorentzou, Athanasios G. KonstandopoulosAbstract:Abstract The present work relates to the investigation of cobalt and manganese oxide based compositions as candidate materials for the Storage of surplus energy, available in the form of Heat, generated from high temperature concentrated solar power plants (e.g. solar tower, solar dish) via a two-step Thermochemical cyclic redox process under air flow. Emphasis is given on the utilization of small structured monolithic bodies (flow-through pellets) made entirely from the two aforementioned oxides. As compared to the respective powders, and in addition to the natural advantage of substantially lower pressure drop that monolithic structures can offer, this study demonstrated that structured bodies can also improve redox kinetics to a measurable extent. Cobalt oxide was found to be superior to manganese oxide both from an estimated energy density and from a redox reactions kinetics point-of-view. Among the redox conditions studied, the optimum reduction-oxidation operating window for the former oxide was determined to be in the range of 1000-800 °C, while for the latter material no clear conclusion was drawn with reduction reaching its maximum extent at 1000 °C and oxidation occurring in the range of 500-650 °C. In both cases, no significant degradation of redox performance was observed upon cyclic operation (up to 10 cycles), however manganese oxide showed notably slower oxidation kinetics.
Alfonso J Carrillo - One of the best experts on this subject based on the ideXlab platform.
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assessing cr incorporation in mn2o3 mn3o4 redox materials for Thermochemical Heat Storage applications
Journal of energy storage, 2021Co-Authors: Alfonso J Carrillo, Patricia Pizarro, Juan M CoronadoAbstract:Abstract Widening the use of renewable sources requires more efficient energy Storage systems to overcome the inherent intermittence of solar energy. In this respect, thermal energy Storage coupled to concentrated solar power represents an inexpensive technology to achieve that goal. In particular, the use of reversible Thermochemical reactions is promising due to a higher energy Storage density if compared with commercial sensible Heat Storage on molten salts. However, some of these systems that rely on gas-solid reactions can suffer a cycle-to-cycle loss of activity due to slow kinetics and materials degradation, which is detrimental for its potential future commercialization. In this work, we have assessed the incorporation of Cr cations in the redox couple Mn2O3/Mn3O4, as a way to stabilize the multi-cyclic activity over prolonged operation at high temperatures (650-1000 °C). Reduction has been studied with in situ XRD and kinetic analyses, which confirm that Cr incorporation shifts the reaction towards high temperatures. Long term redox cycling tests confirm that 5% Cr incorporation helps to stabilize the redox activity of Mn2O3/Mn3O4.
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solar energy on demand a review on high temperature Thermochemical Heat Storage systems and materials
Chemical Reviews, 2019Co-Authors: Alfonso J Carrillo, Jose Gonzalezaguilar, Manuel Romero, Juan M CoronadoAbstract:Among renewable energies, wind and solar are inherently intermittent and therefore both require efficient energy Storage systems to facilitate a round-the-clock electricity production at a global scale. In this context, concentrated solar power (CSP) stands out among other sustainable technologies because it offers the interesting possibility of storing energy collected from the sun as Heat by sensible, latent, or Thermochemical means. Accordingly, continuous electricity generation in the power block is possible even during off-sun periods, providing CSP plants with a remarkable dispatchability. Sensible Heat Storage has been already incorporated to commercial CSP plants. However, because of its potentially higher energy Storage density, Thermochemical Heat Storage (TCS) systems emerge as an attractive alternative for the design of next-generation power plants, which are expected to operate at higher temperatures. Through these systems, thermal energy is used to drive endothermic chemical reactions, which...
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solar energy on demand a review on high temperature Thermochemical Heat Storage systems and materials
Chemical Reviews, 2019Co-Authors: Alfonso J Carrillo, Jose Gonzalezaguilar, Manuel Romero, Juan M CoronadoAbstract:Among renewable energies, wind and solar are inherently intermittent and therefore both require efficient energy Storage systems to facilitate a round-the-clock electricity production at a global scale. In this context, concentrated solar power (CSP) stands out among other sustainable technologies because it offers the interesting possibility of storing energy collected from the sun as Heat by sensible, latent, or Thermochemical means. Accordingly, continuous electricity generation in the power block is possible even during off-sun periods, providing CSP plants with a remarkable dispatchability. Sensible Heat Storage has been already incorporated to commercial CSP plants. However, because of its potentially higher energy Storage density, Thermochemical Heat Storage (TCS) systems emerge as an attractive alternative for the design of next-generation power plants, which are expected to operate at higher temperatures. Through these systems, thermal energy is used to drive endothermic chemical reactions, which can subsequently release the stored energy when needed through a reversible exothermic step. This review analyzes the status of this prominent energy Storage technology, its major challenges, and future perspectives, covering in detail the numerous strategies proposed for the improvement of materials and Thermochemical reactors. Thermodynamic calculations allow selecting high energy density systems, but experimental findings indicate that sufficiently rapid kinetics and long-term stability trough continuous cycles of chemical transformation are also necessary for practical implementation. In addition, selecting easy-to-handle materials with reduced cost and limited toxicity is crucial for large-scale deployment of this technology. In this work, the possible utilization of materials as diverse as metal hydrides, hydroxides, or carbonates for Thermochemical Storage is discussed. Furthermore, special attention is paid to the development of redox metal oxides, such as Co3O4/CoO, Mn2O3/Mn3O4, and perovskites of different compositions, as an auspicious new class of TCS materials due to the advantage of working with atmospheric air as reactant, avoiding the need of gas Storage tanks. Current knowledge about the structural, morphological, and chemical modifications of these solids, either caused during redox transformations or induced wittingly as a way to improve their properties, is revised in detail. In addition, the design of new reactor concepts proposed for the most efficient use of TCS in concentrated solar facilities is also critically considered. Finally, strategies for the harmonic integration of these units in functioning solar power plants as well as the economic aspects are also briefly assessed.
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exploring the Thermochemical Heat Storage capacity of amn2o4 a li or cu spinels
Solid State Ionics, 2018Co-Authors: Ntuthuko Wonderboy Hlongwa, Alfonso J Carrillo, D P Serrano, Patricia Pizarro, Daniel Sastre, Emmanuel I Iwuoha, Chinwe O Ikpo, Juan M CoronadoAbstract:Abstract At present, there is a clear interest in developing redox materials with improved properties for high temperature Thermochemical energy Storage. Chemical modification of manganese oxides with cations such Li and Cu can produce, among other phases, LiMn2O4 and CuMn2O4 spinels, which are feasible candidates for Heat Storage due to their redox capacity. In this work, these materials were synthesized by Pechini method, and the characterization results confirmed the formation of the targeted phases with some minor contribution of Mn3O4. Thermogravimetrical redox tests in air established that both materials experience fully reversible redox transformations when the temperature is varied between 900 and 1000 °C. These assays showed the stability of both Cu and Li mixed oxides after five consecutive redox cycles and, in accordance, the XRD confirmed that the two samples retaining their spinel crystal structure after the treatment. However, in these conditions reduction temperatures are higher than 940 °C for both oxides and the enthalpies of these transformations are modest, with a maximum value of 36 kJ/kg for LiMn2O4. Alternatively, if the reduction is performed in argon and the oxidation in air, it is possible to increase the amount of oxygen exchanged in the gas-solids reactions and, accordingly, the Heat Storage capacity. Therefore, the Heat recovered in the re-oxidation of CuMn2O4 at 700 °C was 144 kJ/kg (34 kJ/mol), while LiMn2O4 showed an enthalpy of 209 kJ/kg (37 kJ/mol). These changes in the composition of the atmosphere do not affect to the stability of the system and the conversion is maintained after five consecutive cycles. In all cases, the initial spinel phase is recovered after reoxidation, which takes place at remarkably fast rates. Analysis of the intermediate reduced materials reveals a significant complexity of the redox transformations, which imply the formation of LiMnO2 and CuMnO2, among other phases. Accordingly, considering the stability of these systems, as well as the relatively high enthalpies CuMn2O4 and LiMn2O4 appear to be promising materials for Thermochemical energy Storage.
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revisiting the bao2 bao redox cycle for solar Thermochemical energy Storage
Physical Chemistry Chemical Physics, 2016Co-Authors: Alfonso J Carrillo, D P Serrano, Patricia Pizarro, Daniel Sastre, Juan M CoronadoAbstract:The barium peroxide-based redox cycle was proposed in the late 1970s as a Thermochemical energy Storage system. Since then, very little attention has been paid to such redox couples. In this paper, we have revisited the use of reduction–oxidation reactions of the BaO2/BaO system for Thermochemical Heat Storage at high temperatures. Using thermogravimetric analysis, reduction and oxidation reactions were studied in order to find the main limitations associated with each process. Furthermore, the system was evaluated through several charge–discharge stages in order to analyse its possible degradation after repeated cycling. Through differential scanning calorimetry the Heat stored and released were also determined. Oxidation reaction, which was found to be slower than reduction, was studied in more detail using isothermal tests. It was observed that the rate-controlling step of BaO oxidation follows zero-order kinetics, although at high temperatures a deviation from Arrhenius behaviour was observed probably due to hindrances to anionic oxygen diffusion caused by the formation of an external layer of BaO2. This redox couple was able to withstand several redox cycles without deactivation, showing reaction conversions close to 100% provided that impurities are previously eliminated through thermal pre-treatment, demonstrating the feasibility of this system for solar Thermochemical Heat Storage.
C Y Zhao - One of the best experts on this subject based on the ideXlab platform.
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multi physics modeling of Thermochemical Heat Storage with enhance Heat transfer
Applied Thermal Engineering, 2021Co-Authors: Tao Shi, Biao Lei, C Y ZhaoAbstract:Abstract Thermochemical Heat Storage technology is an important component in energy system, and plays a key role in the balance of energy supply and demand. A multi-physics model is constructed to study the hydration process in a tubular reactor, including fluid flow, Heat transfer and reaction. Variations of temperature and conversion of CaO are discussed in detailed to reveal exothermic reaction characteristics. Besides, effects of different reaction conditions during hydration are studied, such as porosity, temperature, pressure, flow rate and thermal conductivity. It is found that the low thermal conductivity of solid-phase is the most important factor which limits the reaction. The Heat transfer process can be greatly promoted by adding fins, due to the high Heat conductivity. However, the relationship between the reactor structure and the performance of the Thermochemical Heat Storage is not quantitatively clear. The present study aims to investigate the impact of the arrangement of fins on the hydration process. Finally, different types of fins with high thermal conductivity are employed in the reactor. Attributing to the fact that the equilibrium temperature is affected by the vapor pressure, Thermochemical reactors with different fin configurations have different flow characteristics and pressure drops, leading to different reaction characteristics. It is shown that the exothermic time was reduced to 84.32% (axial fins), 89.97% (radial fins), and 88.71% (spiral fins) of the original, respectively. This study can reveal the coupling relations of multi-physics fields in Thermochemical Heat Storage, and provide theoretical basis for the design of Thermochemical Heat Storage reactors.
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experimental study of mgo mg oh 2 Thermochemical Heat Storage with direct Heat transfer mode
Applied Energy, 2020Co-Authors: Jinyue Yan, Z H Pan, C Y ZhaoAbstract:Abstract Thermochemical Heat Storage uses a reversible chemical reaction to store thermal energy. This thermal energy Storage method has high energy density and allows long-term thermal energy Storage. MgO/Mg(OH)2 is a promising reversible reaction for Thermochemical Heat Storage systems. The performance of this reversible reaction inside a reactor plays a key role in its practical applications. The direct type Heat transfer reactor is a novel design compared with an indirect powder bed reactor. It allows the gaseous Heat transfer fluid to flow through the powder in order to break the Heat transfer limitation from the Heat exchanger between the MgO/Mg(OH)2 powder and the Heat transfer fluid. In this study, we evaluated the performance of a direct type MgO/Mg(OH)2 reactor under various operating conditions. Parametric analyses indicated that the Heat output is limited by the reaction rate rather than the Heat transfer efficiency. Results also showed the best bed thickness in order to achieve the highest temperature output. Material characterization indicated that the MgO/Mg(OH)2 particles did not agglomerate with each other after 15 Heat charging and discharging cycles.
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development of granular Thermochemical Heat Storage composite based on calcium oxide
Renewable Energy, 2020Co-Authors: B Q Xia, C Y Zhao, J Yan, Azhar Abbas KhosaAbstract:Abstract Thermochemical Heat Storage is a promising technology for the efficient utilization of renewable energy. Among available Thermochemical systems, the CaO/Ca(OH)2 system is the most popular because of availability and cost. However, poor powder properties and low Heat Storage rates hinder the successful implementation of this system. This study presented a novel synthetic method of granular composites based on carboxymethyl cellulose sodium (CMC) and vermiculite in order to mitigate the drawbacks of natural materials and stabilize the size of materials for use in moving bed reactors. TGA and DSC experiments and some essential characterizations were done in order to evaluate the improvements on the basis of three objectives: the Heat Storage rate, Heat Storage density, and mechanical properties, compared with natural materials. Results showed that the granular composite still had great structural integrity after several dehydration/hydration cycles, whereas compacted natural materials had fragmented. Additionally, composite had a higher Heat Storage rate than natural materials. The gravimetric Storage density of granular composite was slightly reduced while the volumetric Storage density was enhanced up to approximately 124% as compared to the powdery Ca(OH)2 material. It was concluded that present synthetic method is a promising route for the development of Ca-based composite materials.
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Medium- and high-temperature latent and Thermochemical Heat Storage using metals and metallic compounds as Heat Storage media: A technical review
'Elsevier BV', 2020Co-Authors: Zhao Y, C Y Zhao, Cn Markides, Wang H, Li WAbstract:Latent and Thermochemical Heat Storage technologies are receiving increased attention due to their important role in addressing the challenges of variable renewable energy generation and waste Heat availability, as well as the mismatch between energy supply and demand in time and space. However, as the operating Storage temperature increases, a series of challenging technical problems arise, such as complex Heat transfer mechanisms, increased corrosion, material failure, reduced strength, and high-temperature measurement difficulties, especially for metals and metallic compounds as Heat Storage media. This paper reviews the latest research progress in medium- and high-temperature latent and Thermochemical Heat Storage using metals and metallic compounds as Storage media from a technical perspective and provides useful information for researchers and engineers in the field of energy Storage. In this paper, the status and challenges of medium- and high-temperature latent and Thermochemical Heat Storage are first introduced, followed by an assessment of metals and metallic compounds as Heat Storage media in latent and Thermochemical Heat Storage applications. This is followed by a comprehensive review of three key issues associated with medium/high-temperature latent Heat Storage applications: Heat transfer enhancement, stability and corrosion, as well as a discussion of four key issues associated with medium/high-temperature Thermochemical Heat Storage: Heat transfer, cycling stability, mechanical property and reactor/system design. Finally, the prospects of medium/high-temperature latent and Thermochemical Heat Storage are summarized
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the effect of dehydration temperatures on the performance of the cao ca oh 2 Thermochemical Heat Storage system
Energy, 2019Co-Authors: J Yan, C Y Zhao, Bin Xia, Tao WangAbstract:Abstract A more fundamental understanding of the dehydration and hydration processes of Ca(OH)2 materials is very important for the proper design and operation of Thermochemical Heat Storage systems. There is no simple and effective method which can solve the issues of the rate of the Heat Storage process and the influence of CO2 on Ca(OH)2 materials. Kinetic studies have proven that a high temperature can increase the Storage speed, but a high temperature will aggravate sintering of the material. The problem of carbonate formation due to contact with CO2 can also be solved by a high temperature. Therefore, how to solve the problem of the aggravation of sintering of the material after a single high temperature dehydration is important. In this study, it was found that the Heat release ability can be recovered if the Heat Storage process of the material is applied at a lower temperature in the next cycle. Kinetic studies cannot explain the reasons of these processes. Therefore, the methods of N2 adsorption–desorption and SEM were used to reveal the effects of different dehydration temperatures on the microstructure of the materials. The results showed that the change of the micro-pore structure was the reason for the above processes.
Patricia Pizarro - One of the best experts on this subject based on the ideXlab platform.
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assessing cr incorporation in mn2o3 mn3o4 redox materials for Thermochemical Heat Storage applications
Journal of energy storage, 2021Co-Authors: Alfonso J Carrillo, Patricia Pizarro, Juan M CoronadoAbstract:Abstract Widening the use of renewable sources requires more efficient energy Storage systems to overcome the inherent intermittence of solar energy. In this respect, thermal energy Storage coupled to concentrated solar power represents an inexpensive technology to achieve that goal. In particular, the use of reversible Thermochemical reactions is promising due to a higher energy Storage density if compared with commercial sensible Heat Storage on molten salts. However, some of these systems that rely on gas-solid reactions can suffer a cycle-to-cycle loss of activity due to slow kinetics and materials degradation, which is detrimental for its potential future commercialization. In this work, we have assessed the incorporation of Cr cations in the redox couple Mn2O3/Mn3O4, as a way to stabilize the multi-cyclic activity over prolonged operation at high temperatures (650-1000 °C). Reduction has been studied with in situ XRD and kinetic analyses, which confirm that Cr incorporation shifts the reaction towards high temperatures. Long term redox cycling tests confirm that 5% Cr incorporation helps to stabilize the redox activity of Mn2O3/Mn3O4.
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exploring the Thermochemical Heat Storage capacity of amn2o4 a li or cu spinels
Solid State Ionics, 2018Co-Authors: Ntuthuko Wonderboy Hlongwa, Alfonso J Carrillo, D P Serrano, Patricia Pizarro, Daniel Sastre, Emmanuel I Iwuoha, Chinwe O Ikpo, Juan M CoronadoAbstract:Abstract At present, there is a clear interest in developing redox materials with improved properties for high temperature Thermochemical energy Storage. Chemical modification of manganese oxides with cations such Li and Cu can produce, among other phases, LiMn2O4 and CuMn2O4 spinels, which are feasible candidates for Heat Storage due to their redox capacity. In this work, these materials were synthesized by Pechini method, and the characterization results confirmed the formation of the targeted phases with some minor contribution of Mn3O4. Thermogravimetrical redox tests in air established that both materials experience fully reversible redox transformations when the temperature is varied between 900 and 1000 °C. These assays showed the stability of both Cu and Li mixed oxides after five consecutive redox cycles and, in accordance, the XRD confirmed that the two samples retaining their spinel crystal structure after the treatment. However, in these conditions reduction temperatures are higher than 940 °C for both oxides and the enthalpies of these transformations are modest, with a maximum value of 36 kJ/kg for LiMn2O4. Alternatively, if the reduction is performed in argon and the oxidation in air, it is possible to increase the amount of oxygen exchanged in the gas-solids reactions and, accordingly, the Heat Storage capacity. Therefore, the Heat recovered in the re-oxidation of CuMn2O4 at 700 °C was 144 kJ/kg (34 kJ/mol), while LiMn2O4 showed an enthalpy of 209 kJ/kg (37 kJ/mol). These changes in the composition of the atmosphere do not affect to the stability of the system and the conversion is maintained after five consecutive cycles. In all cases, the initial spinel phase is recovered after reoxidation, which takes place at remarkably fast rates. Analysis of the intermediate reduced materials reveals a significant complexity of the redox transformations, which imply the formation of LiMnO2 and CuMnO2, among other phases. Accordingly, considering the stability of these systems, as well as the relatively high enthalpies CuMn2O4 and LiMn2O4 appear to be promising materials for Thermochemical energy Storage.
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revisiting the bao2 bao redox cycle for solar Thermochemical energy Storage
Physical Chemistry Chemical Physics, 2016Co-Authors: Alfonso J Carrillo, D P Serrano, Patricia Pizarro, Daniel Sastre, Juan M CoronadoAbstract:The barium peroxide-based redox cycle was proposed in the late 1970s as a Thermochemical energy Storage system. Since then, very little attention has been paid to such redox couples. In this paper, we have revisited the use of reduction–oxidation reactions of the BaO2/BaO system for Thermochemical Heat Storage at high temperatures. Using thermogravimetric analysis, reduction and oxidation reactions were studied in order to find the main limitations associated with each process. Furthermore, the system was evaluated through several charge–discharge stages in order to analyse its possible degradation after repeated cycling. Through differential scanning calorimetry the Heat stored and released were also determined. Oxidation reaction, which was found to be slower than reduction, was studied in more detail using isothermal tests. It was observed that the rate-controlling step of BaO oxidation follows zero-order kinetics, although at high temperatures a deviation from Arrhenius behaviour was observed probably due to hindrances to anionic oxygen diffusion caused by the formation of an external layer of BaO2. This redox couple was able to withstand several redox cycles without deactivation, showing reaction conversions close to 100% provided that impurities are previously eliminated through thermal pre-treatment, demonstrating the feasibility of this system for solar Thermochemical Heat Storage.
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improving the Thermochemical energy Storage performance of the mn2o3 mn3o4 redox couple by the incorporation of iron
Chemsuschem, 2015Co-Authors: Alfonso J Carrillo, D P Serrano, Patricia Pizarro, Juan M CoronadoAbstract:Redox cycles of manganese oxides (Mn2 O3 /Mn3 O4 ) are a promising alternative for Thermochemical Heat Storage systems coupled to concentrated solar power plants as manganese oxides are abundant and inexpensive materials. Although their cyclability for such a purpose has been proved, sintering processes, related to the high-temperature conditions at which charge-discharge cycles are performed, generally cause a cycle-to-cycle decrease in the oxidation rate of Mn3 O4 . To guarantee proper operation, both reactions should present stable reaction rates. In this study, it has been demonstrated that the incorporation of Fe, which is also an abundant material, into the manganese oxides improves the redox performance of this system by increasing the Heat Storage density, narrowing the redox thermal hysteresis, and, above all, stabilizing and enhancing the oxidation rate over long-term operation, which counteracts the negative effects caused by sintering, although its presence is not avoided.
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Thermochemical Heat Storage at high temperatures using mn2o3 mn3o4 system narrowing the redox hysteresis by metal co doping
Energy Procedia, 2015Co-Authors: Alfonso J Carrillo, D P Serrano, Patricia Pizarro, Juan M CoronadoAbstract:Abstract Thermal energy Storage systems are a key component of concentrated solar power plants, since its implementation increases the energy generation dispatchability. In particular, Thermochemical Storage through redox cycles of metal oxides is going to play a major role in future plants working with volumetric air receivers, as they are able to store energy at high temperatures, using air as both Heat transfer fluid and reactant. One of the most remarkable characteristics of redox cycles of some metal oxides (e.g. Mn2O3/Mn3O4 and Co3O4/CoO) is that the forward and reverse reactions start at different temperatures, i.e., a thermal hysteresis exists. Namely, the metal oxide reduction takes place at higher temperatures than the re-oxidation of the reduced phase. In the case of Mn-based redox couple, the temperature difference between reduction and oxidation is of ca. 200 °C, whereas for Co3O4/CoO is around 50 °C. Narrowing the hysteresis loop for the manganese oxide system means that Heat is stored and released in a closer range of temperatures, which will suppose an increase of the charge-discharge energy efficiency. In this work, the effect that co-doping the Mn oxides with Fe and Cu has on the redox temperatures of both reactions has been studied. Materials were prepared by a variation of Pechini method and characterized by XRD and SEM. The capacity to withstand several redox cycles was analyzed by thermogravimetric analyses. It was found that addition of certain amount of both dopants narrowed the thermal hysteresis of such redox couple, presenting stable reversibility.
