Session: 06-03 Novel Reactors and Processes

Paper Number: 107871

107871 - Modelling Development of a Receiver-Reactor of Type R2Mx for Thermochemical Water Splitting 

Modelling development of a receiver-reactor of type R2Mx for thermochemical water splitting

Estefania Vega Puga^1,2, Anika Weber^1,2, Stefan Brendelberger¹, Christian Sattler^1,2

1) German Aerospace Center (DLR), Institute of Future Fuels

2) RWTH Aachen University, Chair for Solar Fuel Production  

Solar thermochemical processes are promising technologies for cost effective, large-scale hydrogen and drop-in fuel production. Some of the most investigated thermochemical cycles utilize metal oxides to split water or carbon dioxide in a two-step process, in which the high temperature (1500 °C) requirement is achieved by using concentrated solar radiation. For this, a wide variety of receiver-reactor concepts have been developed ranging from rotating, particle-based to stationary concepts. Up to date, the most advanced system uses stationary monolithic redox structures and has a demonstrated efficiency of 4.1% at 50 kW_thermal scale in field [1]. Further improvements are needed to compete with alternative processes, such as electrolysis-based ones.

With the aim of increasing the solar-to-fuel efficiency the new receiver-reactor concept R2Mx was developed and presented in the work of Brendelberger et al. [2]. Key aspects of the concept include movable monolithic redox structures combined with linear transportation systems and dedicated oxidation reactors. The new receiver-reactor reduces technical challenges associated with particle-based or rotating concepts by keeping the transportation system elementary, while still benefiting from the high efficiency potential of incorporating two physically distinct reaction zones. Unlike the state-of-the-art, the new concept allows for continuous on-sun operation leading to increased efficiency of the solar interface and permitting options for solid heat recovery. The initial numerical assessment of the concept predicts efficiencies above 14%, even for non-optimized designs [2]. For the experimental demonstration of the concept a prototype is being developed at DLR. 

Our recent work builds on the initial 1D model presented in the work of Brendelberger et al. [2] and involves the development of a 3D model of the prototype receiver-reactor. The finite element model is aimed at supporting the design development by providing an in-depth understanding of the underlying heat transfer and evolution of the temperature distribution within a receiver-reactor prototype. The 3D transient thermal analysis is performed utilizing the commercially available ANSYS software, while a realistic heat flux distribution, from the solar simulator at the DLR in Cologne, is obtained via an in-house ray tracing tool. The model includes a reduction reactor, movable redox structures, an oxidation reactor and a gate that separates the reaction zones. The reduction reactor is heated continuously, while the monolithic redox structures are consecutively transported between the reaction zones. Insights on prototype development based on findings are also detailed.

References

1.     Zoller S, Koepf E, Nizamian D, Stephan M, Patané A, Haueter P, et al. A solar tower fuel plant for the thermochemical production of kerosene from H2O and CO2. Joule. 2022;6:1606–16. doi:10.1016/j.joule.2022.06.012.

2.           Brendelberger S, Holzemer-Zerhusen P, Vega Puga E, Roeb M, Sattler C. Study of a new receiver-reactor cavity system with multiple mobile redox units for solar thermochemical water splitting. Solar Energy. 2022;235:118–28. doi:10.1016/j.solener.2022.02.013.

Presenting Author: Estefania Vega Puga German Aerospace Center (DLR)

Presenting Author Biography: Estefania Vega Puga is a Ph.D. candidate at the German Aerospace Center in the field of solar thermochemical fuel production. She obtained her M. Sc. in Energy Engineering and Management from the Karlsruhe Institute of Technology and her B.Eng. in Mechanical and Nuclear Engineering from the University of Manchester. Her current research interests include high temperature solar chemistry, numerical modelling as well as receiver-reactor design and optimization.