scholarly journals Thermodynamic Analysis of a Conceptual Fixed-Bed Solar Thermochemical Cavity Receiver–Reactor Array for Water Splitting Via Ceria Redox Cycling

2021 ◽  
Vol 9 ◽  
Author(s):  
Song Yang ◽  
Lifeng Li ◽  
Bo Wang ◽  
Sha Li ◽  
Jun Wang ◽  
...  
Keyword(s):  
Gas Phase ◽  
Thermal Performance ◽  
Heat Recovery ◽  
Concentration Ratio ◽  
Solid Phase ◽  
Fuel Efficiency ◽  
Fixed Bed ◽  
Redox Cycling ◽  
Linear Matrix ◽  
Solar Thermochemical

We propose a novel solar thermochemical receiver–reactor array concept for hydrogen production via ceria redox cycling. The receiver–reactor array can improve the solar-to-fuel efficiency by realizing the heat recuperation, reduction, and oxidation processes synchronously. A linear matrix model and a lumped parameter model are developed to predict thermal performance of the new solar thermochemical system. The system thermal performance is characterized by heat recovery effectiveness of solid-phase and solar-to-fuel efficiency. Investigated parameters include reduction temperature, oxygen partial pressure, number of receiver–reactors, concentration ratio, and gas-phase heat recovery effectiveness. For baseline conditions, the solid-phase heat recovery effectiveness and the solar-to-fuel efficiency are found to be 81% and 27%, respectively. For perfect gas-phase heat recovery and a solar concentration ratio of 5,000, the solar-to-fuel efficiency exceeds 40%.

scholarly journals Solar thermochemical CO2 splitting with doped perovskite LaCo0.7Zr0.3O3: thermodynamic performance and solar-to-fuel efficiency

RSC Advances ◽  
2020 ◽  
Vol 10 (59) ◽  
pp. 35740-35752
Author(s):  
Lei Wang ◽  
Tianzeng Ma ◽  
Shaomeng Dai ◽  
Ting Ren ◽  
Zheshao Chang ◽  
...  
Keyword(s):  
Solid Phase ◽  
Fuel Efficiency ◽  
Thermodynamics Analysis ◽  
Thermodynamic Performance ◽  
Heat Recuperation ◽  
Solar Thermochemical

Thermodynamics analysis of two-step thermochemical CO2 splitting with LaCo0.7Zr0.3O3 with gas–gas, gas–solid phase heat recuperation is performed based on experiment.

Design, Evaluation, and Testing of a Moderately Concentrating, Nontracking Solar Energy Collector

1981 ◽  
Vol 103 (1) ◽  
pp. 34-41 ◽  
Author(s):  
A. Olvera ◽  
R. B. Bannerot
Keyword(s):  
Solar Energy ◽  
Heat Loss ◽  
Thermal Performance ◽  
Heat Recovery ◽  
Concentration Ratio ◽  
Side Wall ◽  
Recovery Factor ◽  
Design Evaluation ◽  
Optical Efficiency ◽  
Overall Heat Loss Coefficient

The thermal performance of a moderately concentrating, nontracking, trough-like solar energy collector is predicted based on a series of experimental evaluations of its components. Four reflector designs were constructed and tested. Two were one-facet side wall (reflector) designs; two were two-facet designs. Six simple tubular, nonevacuated receiver designs were tested. A collector utilizing one of the reflector designs, geometric concentration ratio of 2.6, and one of the receiver designs was constructed and tested. The predicted performance (an effective overall heat loss coefficient of 4.6 W/m2–°C, an optical efficiency of 0.71 and a heat recovery factor of 0.95) closely approximated the actual thermal performance of the collector. The component evaluations are discussed in such detail that the analysis could easily be extended to other designs by the reader.

Dynamics of gas phase and solid phase reactions in fixed bed reactors

1996 ◽  
Vol 51 (11) ◽  
pp. 3083-3088 ◽  
Author(s):  
Milind S. Kulkarni ◽  
Milorad P. Dudukovic'
Keyword(s):  
Gas Phase ◽  
Solid Phase ◽  
Fixed Bed ◽  
Fixed Bed Reactors ◽  
Solid Phase Reactions

Transient Three-Dimensional Heat Transfer Model of a Solar Thermochemical Reactor for H2O and CO2 Splitting Via Nonstoichiometric Ceria Redox Cycling

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Justin Lapp ◽  
Wojciech Lipiński
Keyword(s):  
Heat Transfer ◽  
Heat Recovery ◽  
Fuel Efficiency ◽  
Radiation Heat Transfer ◽  
Three Dimensional ◽  
Heat Transfer Model ◽  
Heat Fluxes ◽  
Transfer Model ◽  
Solar Thermochemical ◽  
Solar Receiver

A transient three-dimensional heat transfer model is developed for a 3 kWth solar thermochemical reactor for H2O and CO2 splitting via two-step nonstoichiometric ceria cycling. The reactor consists of a windowed solar receiver cavity, counter-rotating reactive and inert cylinders, and insulated reactor walls. The counter-rotating cylinders allow for continuous fuel production and heat recovery. The model is developed to solve energy conservation equations accounting for conduction, convection, and radiation heat transfer modes, and chemical reactions. Radiative heat transfer is analyzed using a combination of the Monte Carlo ray-tracing method, the net radiation method, and the Rosseland diffusion approximation. Steady-state temperatures, heat fluxes, and nonstoichiometry are reported. A temperature swing of up to 401 K, heat recovery effectiveness of up to 95%, and solar-to-fuel efficiency of up to 5% are predicted in parametric studies.

Predicted Performance of a Ceramic Foam Gas Phase Heat Recuperator for a Solar Thermochemical Reactor

2014 ◽  
Author(s):  
Rohini Bala Chandran ◽  
Aayan Banerjee ◽  
Jane H. Davidson
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Gas Phase ◽  
Heat Recovery ◽  
Porous Alumina ◽  
Porous Ceramic ◽  
Thermal Reduction ◽  
Operating Conditions ◽  
Ceramic Foam ◽  
Solar Thermochemical

The efficiency of solar thermochemical cycles to split water and carbon dioxide depends in large part on highly effective gas phase heat recovery. Heat recovery is imperative for approaches that rely on an inert sweep gas to reach low partial pressures of oxygen during thermal reduction and/or use excess oxidizer to provide a higher thermodynamic driving potential for fuel production. In this paper, we analyze heat transfer and pressure drop of a tube-in-tube ceramic heat exchanger for the operating conditions expected in a prototype solar reactor for isothermal cycling of ceria. The ceramic tubes are filled with reticulated porous ceramic (RPC). The impacts of the selection of the composition and morphology of the RPC on heat transfer and pressure drop are explored via computational analysis. Results indicate a 10 pore per inch (ppi), 80–85% porous alumina RPC yields effectiveness from 85 to 90 percent.

Modeling of aerated upflow fixed bed reactors for nitrification

1999 ◽  
Vol 39 (4) ◽  
pp. 85-92 ◽  
Author(s):  
J. Behrendt
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Liquid Phase ◽  
Gas Phase ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Bulk Liquid ◽  
Initial Value ◽  
Fixed Bed Reactors ◽  
Number Of Cells

A mathematical model for nitrification in an aerated fixed bed reactor has been developed. This model is based on material balances in the bulk liquid, gas phase and in the biofilm area. The fixed bed is divided into a number of cells according to the reduced remixing behaviour. A fixed bed cell consists of 4 compartments: the support, the gas phase, the bulk liquid phase and the stagnant volume containing the biofilm. In the stagnant volume the biological transmutation of the ammonia is located. The transport phenomena are modelled with mass transfer formulations so that the balances could be formulated as an initial value problem. The results of the simulation and experiments are compared.

Transient Three-Dimensional Heat Transfer Model of a Solar Thermochemical Reactor for H2O and CO2 Splitting via Nonstoichiometric Ceria Redox Cycling

2013 ◽  
Author(s):  
Justin Lapp ◽  
Wojciech Lipiński
Keyword(s):  
Heat Transfer ◽  
Heat Recovery ◽  
Fuel Efficiency ◽  
Three Dimensional ◽  
Reactor Design ◽  
Heat Transfer Model ◽  
Heat Fluxes ◽  
Transfer Model ◽  
Rotating Cylinders ◽  
Solar Receiver

A transient heat transfer model is developed for a solar reactor prototype for H2O and CO2 splitting via two-step non-stoichiometric ceria cycling. Counter-rotating cylinders of reactive and inert materials cycling between high and low temperature zones permit continuous operation and heat recovery. To guide the reactor design a transient three-dimensional heat transfer model is developed based on transient energy conservation, accounting for conduction, convection, radiation, and chemical reactions. The model domain includes the rotating cylinders, a solar receiver cavity, and insulated reactor body. Radiative heat transfer is analyzed using a combination of the Monte Carlo method, Rosseland diffusion approximation, and the net radiation method. Quasi-steady state distributions of temperatures, heat fluxes, and the non-stoichiometric coefficient are reported. Ceria cycles between temperatures of 1708 K and 1376 K. A heat recovery effectiveness of 28% and solar-to-fuel efficiency of 5.2% are predicted for an unoptimized reactor design.

Validating Soot Models in LES of Turbulent Flames: The Contribution of Soot Subgrid Intermittency Model to The Prediction of Soot Production in an Aero-Engine Model Combustor

2021 ◽  
Author(s):  
Lívia Pereira Tardelli ◽  
Nasser Darabiha ◽  
Denis Veynante ◽  
Benedetta Franzelli
Keyword(s):  
Gas Phase ◽  
Reference Model ◽  
Solid Phase ◽  
Phase Evolution ◽  
Turbulent Flames ◽  
Engine Model ◽  
Aero Engine ◽  
New Strategy ◽  
Parametric Studies ◽  
Soot Model

Abstract Predicting soot production in industrial systems using an LES approach represents a great challenge. Besides the complexity in modeling the multi-scale physicochemical soot processes and their interaction with turbulence, the validation of newly developed models is critical under turbulent conditions. This work illustrates the difficulties in evaluating model performances specific to soot prediction in turbulent flames by considering soot production in an aero-engine combustor. It is proven that soot production occurs only for scarce local gaseous conditions. Therefore, to obtain a statistical representation of such rare soot events, massive CPU resources would be required. For this reason, evaluating soot model performances based on parametric studies, i.e., multiple simulations, as classically done for purely gaseous flames, is CPU high-demanding for sooting flames. Then, a new strategy to investigate modeling impact on the solid phase is proposed. It is based on a unique simulation, where the set of equations describing the solid phase are duplicated. One set accounts for the reference model, while the other set is treated with the model under the scope. Assuming neglected solid phase retro-coupling on the gas phase, the soot scalars from both sets experience the same unique temporal and spatial gas phase evolution isolating the soot model effects from the uncertainties on gaseous models and numerical sensitivities. Finally, the strategy capability is proven by investigating the contribution of the soot subgrid intermittency model to the prediction of soot production in the DLR burner.

Sign in / Sign up

Export Citation Format

Share Document