Dynamic Operation of Electrolyzers – Systems Design and Operating Strategies

Tjarks, Geert; Mergel, Jürgen; Stolten, Detlef

doi:10.1002/9783527674268.ch14

Cited by 6 publications

(6 citation statements)

References 20 publications

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“…The quality of these equations depends on the availability of accurate experimental and simulation data. − For aqueous alkaline solutions, experimental data for self-diffusivities and solubilities of H 2 and O 2 at high concentrations (above 4 mol/kg), temperatures (323–373 K), and pressures (above 50 bar) is lacking, especially in the case of aqueous NaOH solutions. , These temperatures (ca. 353 K) and concentrations (4–12 mol/kg electrolyte solution) are especially relevant for alkaline electrolyzers. ,,− Molecular simulations (i.e., molecular dynamics (MD) and Monte Carlo (MC)) can be used as a complementary approach to experiments to provide insight at conditions for which experimental data are limited and difficult to obtain due to high temperatures, pressures, and the corrosiveness of the solution (in case of strong alkaline solutions).…”

Section: Introductionmentioning

confidence: 99%

A New Force Field for OH^– for Computing Thermodynamic and Transport Properties of H₂ and O₂ in Aqueous NaOH and KOH Solutions

et al. 2022

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The thermophysical properties of aqueous electrolyte solutions are of interest for applications such as water electrolyzers and fuel cells. Molecular dynamics (MD) and continuous fractional component Monte Carlo (CFCMC) simulations are used to calculate densities, transport properties (i.e., self-diffusivities and dynamic viscosities), and solubilities of H2 and O2 in aqueous sodium and potassium hydroxide (NaOH and KOH) solutions for a wide electrolyte concentration range (0–8 mol/kg). Simulations are carried out for a temperature and pressure range of 298–353 K and 1–100 bar, respectively. The TIP4P/2005 water model is used in combination with a newly parametrized OH– force field for NaOH and KOH. The computed dynamic viscosities at 298 K for NaOH and KOH solutions are within 5% from the reported experimental data up to an electrolyte concentration of 6 mol/kg. For most of the thermodynamic conditions (especially at high concentrations, pressures, and temperatures) experimental data are largely lacking. We present an extensive collection of new data and engineering equations for H2 and O2 self-diffusivities and solubilities in NaOH and KOH solutions, which can be used for process design and optimization of efficient alkaline electrolyzers and fuel cells.

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Section: Introductionmentioning

confidence: 99%

A New Force Field for OH^– for Computing Thermodynamic and Transport Properties of H₂ and O₂ in Aqueous NaOH and KOH Solutions

et al. 2022

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“…The electrolyzer is constrained at the upper boundary of the operating window by lifetime issues that are considered in a typical range of current density and cell voltage. The lower boundary of the operating window is constrained by hydrogen contamination in the oxygen flow leaving the anode of the electrolyzer . Constraints of the operating temperature and pressure are chosen to be within typical values for the EO process and the electrolyzer.…”

Section: Framework Resultsmentioning

confidence: 99%

Indirect Demand Response Potential of Large-Scale Chemical Processes

Bruns

Pretoro

Grünewald

et al. 2021

Ind. Eng. Chem. Res.

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The participation of power-intensive chemical processes in demand response programs is seen to provide grid stability and potentially reduce the operating costs of these processes. Large-scale processes that require intermediate products that can be produced by demand response scheduling of a suitable preprocess are an option to be utilized as grid energy storage. In this light, we determine the demand response potential of the novel process route of the production process of ethylene oxide that is coupled to a polymer electrolyte membrane electrolysis process through process-specific analysis and scenario-dependent economic evaluation. We apply an innovative combination of mathematical tools in the consecutive steps of a demand-side management framework. The sequential approach is able to break down the complexity of the demand response operation of such processes into manageable subproblems. The case study illustrates the approach and proves its general validity in quantifying the potential application of large-scale processes in demand response programs.

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“…In practice, this is challenging because the flexibility of PEM electrolysis is limited at the upper boundary of the operating window by lifetime issues and at the lower boundary by gas purities. 38 A decrease in current density results in increasing oxygen contamination with hydrogen on the anode side of the electrolysis. The formed mixture is highly combustible at concentrations above 4% hydrogen in the oxygen stream.…”

Section: Optimization For a Specific Operating Windowmentioning

confidence: 99%

Dynamic Design Optimization for Flexible Process Equipment

Bruns

Herrmann

Grünewald

et al. 2021

Ind. Eng. Chem. Res.

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Recent developments have led to increasing demand for flexible process equipment in several fields of chemical engineering. The design of such equipment is still a very challenging task because feasibility must be assured not only at the steady state but also during dynamic transitions. We present a model-based approach that exploits dynamic optimization for the design of flexible process equipment. The approach is based on a general formulation of the operating window, allowing the operating window to become part of the optimization problem. Furthermore, the approach includes dynamics such that feasible steady-state and dynamic operation is assured. Due to its general formulation, the design approach is applicable for different types of process equipment. We perform the approach on two case studies with backgrounds in demand-side management. In these case studies, we successfully demonstrate the versatility and applicability of the developed approach. Results indicate the impact of different parameters on the equipment flexibility.

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Dynamic Operation of Electrolyzers – Systems Design and Operating Strategies

Cited by 6 publications

References 20 publications

A New Force Field for OH^– for Computing Thermodynamic and Transport Properties of H₂ and O₂ in Aqueous NaOH and KOH Solutions

A New Force Field for OH^– for Computing Thermodynamic and Transport Properties of H₂ and O₂ in Aqueous NaOH and KOH Solutions

Indirect Demand Response Potential of Large-Scale Chemical Processes

Dynamic Design Optimization for Flexible Process Equipment

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Dynamic Operation of Electrolyzers – Systems Design and Operating Strategies

Cited by 6 publications

References 20 publications

A New Force Field for OH– for Computing Thermodynamic and Transport Properties of H2 and O2 in Aqueous NaOH and KOH Solutions

A New Force Field for OH– for Computing Thermodynamic and Transport Properties of H2 and O2 in Aqueous NaOH and KOH Solutions

Indirect Demand Response Potential of Large-Scale Chemical Processes

Dynamic Design Optimization for Flexible Process Equipment

Contact Info

Product

Resources

About

A New Force Field for OH^– for Computing Thermodynamic and Transport Properties of H₂ and O₂ in Aqueous NaOH and KOH Solutions

A New Force Field for OH^– for Computing Thermodynamic and Transport Properties of H₂ and O₂ in Aqueous NaOH and KOH Solutions