Solar electricity via an Air Brayton cycle with an integrated two-step thermochemical cycle for heat storage based on Co3O4/CoO redox reactions: Thermodynamic analysis

Schrader, Andrew J.; Muroyama, Alexander P.; Loutzenhiser, Peter G.

doi:10.1016/j.solener.2015.05.045

Cited by 76 publications

(22 citation statements)

References 34 publications

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“…In a previous work, a thermodynamic analysis of a twostep solar thermochemical cycle for heat storage was performed with integration into an Air Brayton cycle (Schrader et al, 2015). The first step of the cycle is the endothermic thermolysis of Co 3 O 4 driven by concentrated solar irradiation, represented as:…”

Section: Introductionmentioning

confidence: 99%

Solar electricity via an Air Brayton cycle with an integrated two-step thermochemical cycle for heat storage based on Co3O4/CoO redox reactions II: Kinetic analyses

2015

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A two-step solar thermochemical cycle based on Co 3 O 4 /CoO redox reactions integrated into an Air Brayton cycle is considered for thermochemical heat storage. The two-step cycle encompasses (1) the thermolysis of Co 3 O 4 to CoO and O 2 driven by concentrated solar irradiation and (2) the re-oxidation of CoO with O 2 to Co 3 O 4 , releasing heat and completing the cycle. The cycle steps can be decoupled, allowing for thermochemical heat storage and integration into an Air Brayton cycle for continuous electricity production. Kinetic analyses to identify the rate limiting mechanisms and determine kinetic parameters for both the thermolysis of Co 3 O 4 and the re-oxidation of CoO with O 2 were performed using a combination of isothermal and non-isothermal thermogravimetry. The Co 3 O 4 thermolysis between 1113 and 1213 K followed an Avrami-Erofeyev nucleation model with an Avrami constant of 1.968 and apparent activation energy of 247.21 kJ mol À1 . The O 2 partial pressure dependence between 0% and 20% O 2 -Ar was determined with a power rate law, resulting in a reaction order of 1.506. Ionic diffusion was the rate limiting step for CoO oxidation between 450 and 750 K with an apparent activation energy of 58.07 kJ mol À1 and no evident dependence on O 2 concentration between 5% and 100% O 2 -Ar. Solid characterization was performed using scanning electron microscopy and X-ray powder diffraction.

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Section: Introductionmentioning

confidence: 99%

Solar electricity via an Air Brayton cycle with an integrated two-step thermochemical cycle for heat storage based on Co3O4/CoO redox reactions II: Kinetic analyses

2015

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“…Schrader et al [5] suggested a similar concept for thermochemical energy storage, where cobalt oxide is applied under pressurized conditions in a closed system. In addition, the utilization of particles as heat transfer and thermal storage material has been also investigated for sensible energy storage [6][7][8]. Owing to the high temperature level in the solar receiver, it is crucial to extract both the thermochemical energy and inherent sensible energy of the metal-oxide particles in the heat extraction reactor to enhance the total energy density and system efficiency.…”

Section: Introductionmentioning

confidence: 99%

A Moving Bed Reactor for Thermochemical Energy Storage Based on Metal Oxides

Preisner

Linder

2020

Energies

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High-temperature thermal energy storage enables concentrated solar power plants to provide base load. Thermochemical energy storage is based on reversible gas-solid reactions and brings along the advantage of potential loss-free energy storage in the form of separated reaction products and possible high energy densities. The redox reaction of metal oxides is able to store thermal energy at elevated temperatures with air providing the gaseous reaction partner. However, due to the high temperature level, it is crucial to extract both the inherent sensible and thermochemical energies of the metal-oxide particles for enhanced system efficiency. So far, experimental research in the field of thermochemical energy storage focused mainly on solar receivers for continuously charging metal oxides. A continuously operated system of energy storage and solar tower decouples the storage capacity from generated power with metal-oxide particles applied as heat transfer medium and energy storage material. Hence, a heat exchanger based on a countercurrent moving bed concept was developed in a kW-scale. The reactor addresses the combined utilization of the reaction enthalpy of the oxidation and the extraction of thermal energy of a manganese-iron-oxide particle flow. A stationary temperature profile of the bulk was achieved with two distinct temperature sections. The oxidation induced a nearly isothermal section with an overall stable off-gas temperature. The oxidation and heat extraction from the manganese-iron oxide resulted in a total energy density of 569 kJ/kg with a thermochemical share of 21.1%.

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“…Since oxygen from ambient air can be used as the reaction gas for a thermochemical reaction, no separate gaseous storage is necessary. The concept of two interconnected reactors for continuous charging and discharging is presented by Schrader et al [28] with CoO as thermochemical storage material and heat transfer medium. A solar reactor for reduction and an oxidation reactor are combined with cold and hot storage tanks to feed an air Brayton cycle.…”

Section: Introductionmentioning

confidence: 99%

Stabilizing Particles of Manganese‐Iron Oxide with Additives for Thermochemical Energy Storage

Preisner¹,

Block²,

Linder³

et al. 2018

Energy Tech

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Manganese‐iron oxide particles are a promising candidate for both chemical‐looping combustion (CLC) and thermochemical energy storage. In CLC, the ability of metal oxides to oxidize fuels in an oxygen‐free atmosphere and re‐oxidize in air is addressed. Whereas, reaction enthalpy is the main focus of thermochemical energy storage for, e. g. concentrated solar power or an industrial process that requires high temperature levels. Sufficient mechanical strength of the particles while they endure chemical, thermal, or mechanical stress is a crucial factor for both concepts. Particle stability is investigated here by adding 20 wt.% of TiO2, ZrO2, or CeO2 as a supportive material to (Mn0.7Fe0.3)2O3. Thermal cyclization and temperature shock tests are conducted in a packed bed reactor to identify chemical stability as well as the effect of chemical and thermal stress. A subsequent particle size distribution analysis is performed to determine the relevant breakage mechanism. Attrition resistance is tested with a customized attrition jet cup to estimate the mechanical strength of particles. It is found that the high tendency of unsupported manganese‐iron oxide particles towards agglomeration can be improved with any of the chosen additives. The particles with CeO2, and especially with ZrO2, as an additive indicate an increase in resistance towards attrition. However, adding TiO2 has a severe negative impact on the chemical reactivity of the manganese‐iron oxide.

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Solar electricity via an Air Brayton cycle with an integrated two-step thermochemical cycle for heat storage based on Co3O4/CoO redox reactions: Thermodynamic analysis

Cited by 76 publications

References 34 publications

Solar electricity via an Air Brayton cycle with an integrated two-step thermochemical cycle for heat storage based on Co3O4/CoO redox reactions II: Kinetic analyses

Solar electricity via an Air Brayton cycle with an integrated two-step thermochemical cycle for heat storage based on Co3O4/CoO redox reactions II: Kinetic analyses

A Moving Bed Reactor for Thermochemical Energy Storage Based on Metal Oxides

Stabilizing Particles of Manganese‐Iron Oxide with Additives for Thermochemical Energy Storage

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