Development of a 5 kWth windowless packed-bed reactor for high-temperature solar thermochemical processing

Abstract The new generation of Concentrated Solar Power (CSP) plants requires high temperature and high energy density storage system with good cyclic stability. The potential solution satisfying such requirements is the thermochemical energy storage (TCES) using gas-solid redox reaction. Design of efficient storage reactor is very critical for applications of such storage systems. Packed bed reactors have a simpler design with no moving components and are more cost-effective compared to other available moving bed design configurations while having high-pressure drop is their main drawback. Any improvement in the pressure drop makes the design more suitable for commercial applications, especially at high temperature operating conditions. Cobalt oxide redox reaction has been considered for this study because of its unique features, especially high enthalpy of reaction (energy density) and high reaction temperature. A rectangular cross-section packed bed reactor with a large aspect ratio is selected as a reference conventional packed bed reactor. The novel split-flow packed bed reactor design configuration is proposed in which a portion of heat transfer fluid is passed through adjacent side channels. The split flow ratio of 1/3 has been considered for the case study. The transient two-dimensional numerical model is developed for solving mass, momentum, and energy equations for both gas and solid phases using suitable reaction kinetics for the reversible reduction and re-oxidation process. Complete storage cycle, including both the charging and discharging mode, has been simulated using finite element method. The split flow design performance is compared with the reference case considering the same size of the reaction bed. It is shown that the conversion time is increased while the pressure drop reduced below half of the pressure loss of the conventional design. Reduced mass flow rate passing through the bed results in considerable improvement in required pressure work with a penalty of storage performance. Further study is needed to optimize the split flow ratio and the surface heat transfer characteristics of the bed. The proposed design configuration could be a breakthrough in packed bed reactors, especially for high-temperature storage applications.

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A New Reactor Concept for Efficient Solar-Thermochemical Fuel Production

Journal of Solar Energy Engineering ◽

10.1115/1.4023356 ◽

2013 ◽

Vol 135 (3) ◽

Cited By ~ 142

Author(s):

Ivan Ermanoski ◽

Nathan P. Siegel ◽

Ellen B. Stechel

Keyword(s):

Solar Energy ◽

High Efficiency ◽

Packed Bed ◽

Operating Conditions ◽

Packed Bed Reactor ◽

Reactive Material ◽

Starting Point ◽

Wide Range ◽

Solar Thermochemical ◽

The U.S

We describe and analyze the efficiency of a new solar-thermochemical reactor concept, which employs a moving packed bed of reactive particles produce of H2 or CO from solar energy and H2O or CO2. The packed bed reactor incorporates several features essential to achieving high efficiency: spatial separation of pressures, temperature, and reaction products in the reactor; solid–solid sensible heat recovery between reaction steps; continuous on-sun operation; and direct solar illumination of the working material. Our efficiency analysis includes material thermodynamics and a detailed accounting of energy losses, and demonstrates that vacuum pumping, made possible by the innovative pressure separation approach in our reactor, has a decisive efficiency advantage over inert gas sweeping. We show that in a fully developed system, using CeO2 as a reactive material, the conversion efficiency of solar energy into H2 and CO at the design point can exceed 30%. The reactor operational flexibility makes it suitable for a wide range of operating conditions, allowing for high efficiency on an annual average basis. The mixture of H2 and CO, known as synthesis gas, is not only usable as a fuel but is also a universal starting point for the production of synthetic fuels compatible with the existing energy infrastructure. This would make it possible to replace petroleum derivatives used in transportation in the U.S., by using less than 0.7% of the U.S. land area, a roughly two orders of magnitude improvement over mature biofuel approaches. In addition, the packed bed reactor design is flexible and can be adapted to new, better performing reactive materials.

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Calcium oxide/carbon dioxide reactivity in a packed bed reactor of a chemical heat pump for high-temperature gas reactors

Nuclear Engineering and Design ◽

10.1016/s0029-5493(01)00421-6 ◽

2001 ◽

Vol 210 (1-3) ◽

pp. 1-8 ◽

Cited By ~ 38

Author(s):

Yukitaka Kato ◽

Mitsuteru Yamada ◽

Toshihiro Kanie ◽

Yoshio Yoshizawa

Keyword(s):

Carbon Dioxide ◽

High Temperature ◽

Heat Pump ◽

Calcium Oxide ◽

Packed Bed ◽

Packed Bed Reactor ◽

Chemical Heat ◽

Chemical Heat Pump ◽

Carbon Dioxide Reactivity ◽

High Temperature Gas

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Heat and Mass Transfer Model of a Packed-Bed Reactor for Solar Thermochemical CO2 Capture

Proceedings of the 15th International Heat Transfer Conference ◽

10.1615/ihtc15.pmd.008893 ◽

2014 ◽

Cited By ~ 1

Author(s):

Leanne Reich ◽

Roman Bader ◽

Terrence W. Simon ◽

Wojciech Lipinski

Keyword(s):

Mass Transfer ◽

Heat And Mass Transfer ◽

Co2 Capture ◽

Packed Bed ◽

Packed Bed Reactor ◽

Transfer Model ◽

Mass Transfer Model ◽

Solar Thermochemical

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Parametric Study of Split Flow Cylindrical Packed Bed Reactor for High-Temperature Thermochemical Energy Storage Using Cobalt Oxide Redox Reaction

Volume 6: Energy ◽

10.1115/imece2019-10956 ◽

2019 ◽

Author(s):

Nasser Vahedi ◽

Alparslan Oztekin

Keyword(s):

High Temperature ◽

Energy Storage ◽

Pressure Drop ◽

Parametric Study ◽

Redox Reaction ◽

Packed Bed ◽

Reactor Design ◽

Packed Bed Reactor ◽

Reactor Performance ◽

Split Flow

Abstract Thermal energy storage has become an integral part of Concentrated Solar Power (CSP) plants to guarantee continuous supply of power demand. For cost-effective solar power generation, the size and operating temperatures of CSP plants should be increased. Thermochemical energy storage (TCES) is the only available solution to meet energy density and high-temperature requirements. Air is mostly used as Heat Transfer Fluid (HTF) for high-temperature CSP plants. For the air-based system, metal redox reactions are good candidates as storage reactant. Application of metal oxide gas-solid redox reaction in storage systems requires an efficient reactor design. Cost-effectiveness and simplicity have made packed bed reactors a viable candidate for high-temperature applications. The high-pressure drop along the bed is the main drawback of such reactors preventing them from widespread applications. Split flow design modification could aid in reducing pressure drop while providing more flexibility in reactor performance control. A cylindrical split-flow packed bed reactor with an annulus for HTF flow is considered as a modified reactor design. The transient two-dimensional axisymmetric numerical model is developed for solving mass, momentum, and energy equations for both gas and solid phases using suitable reaction kinetics for the cobalt oxide redox reaction. A parametric study is performed on cylindrical-shaped split-flow reactor design as a basis for future optimization for complete storage cycle. The effect of split flow ratio and side-channel width on reactor performance are considered. It is shown that both parameters could be used effectively to design and optimize the reactor.

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