Project abstract
The innovation pool project “Solar hydrogen - highly pure and compressed (Solarer Wasserstoff – hochrein und komprimiert)” is funded by Helmholtz - Programm MTET. The project will last for three years (01.01.2021-12.31.2023). The project aims to provide essential scientific knowledge and viable technologies for converting solar energy into green hydrogen with the highest possible purity at a high pressure. A very advancing technology to produce solar hydrogen is the methane pyrolysis in liquid metal. Two groups from Institut für Thermische Energietechnik und Sicherheit (ITES) of KIT are involved in the development of this technology. KALLA group is conducting the relevant experiments in order to improving the solar hydrogen converting effectiveness for instance. H2 group is responsible for the solar hydrogen purification and the safety issues. In the solar hydrogen purification work, the left methane and carbon particles will be separated from hydrogen by the membrane and porous media in the purification system. The tasks are to develop physical models and perform high fidelity direct numerical simulations of the hydrogen purification process and analyze the potential safety issues using the GASFLOW code.
Goals
The overall goal of the whole innovation project is to develop technologies which allow to use solar energy to produce pure and highly compressed hydrogen safely at very low cost in the future. It will make a significant contribution to the design of a sustainable energy system in Germany and in the worldwide. The objective of the numerical modeling of purification and safety of solar hydrogen consists of developing the purification model for filtering the carbon particles and separating the left methane in the production, meanwhile ensuring the system running safely.
Project Description
• Background
The “Solar Hydrogen” innovation pool project aims to provide essential scientific knowledge and viable technologies for converting solar energy into hydrogen with the highest possible value for a sustainable energy system in Germany and worldwide [1]. The technologies pursued in the project are therefore characterized by the fact that they enable the generation of solar hydrogen with high purity and high pressure. Solar hydrogen, which has these properties, can be used to in particularly high-quality applications (e.g. operation of a hydrogen fuel cell in cars). In this way, new technologies that can use solar energy to provide high-purity and compressed hydrogen at very low cost in the future make a special contribution to combining effective climate protection, security of supply and economic efficiency.
In the Helmholtz Association, the topic of “solar hydrogen” is pursued with different, complementary, innovative technological approaches at the highest scientific level [1]. The participating scientists expect a particularly intensive scientific exchange of research approaches and process concepts from each other, a joint evaluation of the technologies for the production of solar hydrogen and the quality and suitability of the hydrogen provided with regard to the relevant applications.
• Research field
A very advancing technology to produce solar hydrogen is the methane pyrolysis in liquid metal [2]. Two groups from Institut für Thermische Energietechnik und Sicherheit (ITES) of KIT are involved in the development of this technology. One group is conducting the relevant experiments in order to improving the solar hydrogen converting effectiveness for instance. Our group is responsible for the solar hydrogen purification and the safety issues. In the solar hydrogen purification work, the left methane and carbon particles will be separated from hydrogen by the membrane and porous media in the purification system, in order to fulfill the requirements [3]. Our tasks are to develop physical models and perform high fidelity direct numerical simulations of the hydrogen purification process and analyze the potential safety issues.
• Underlying theory
The solar hydrogen purification work, e.g. the filtering the carbon particles via porous media, involves the dynamics of the gas phase (hydrogen and methane, etc.) and the solid phase (carbon particles) in the complex geometry filed (porous media). Therefore, the underlying theory adopted in the project is the Continuum Mechanics, which specifically is the computational fluid dynamics.
• Description of goals
The objective of the numerical modeling of purification and safety of solar hydrogen consists of developing the purification model for filtering the carbon particles and separating the left methane in the production, meanwhile ensuring the system running safely. The goal consists of the computations of the flows of the gases (hydrogen and methane) and the carbon particles.
• Mathematical model
The main theory adopted in the project is the computational fluid dynamics so that the mathematical model is Navier-Stokes-Equations with turbulence model, two-phase Lagrangian particle model and porous media model. In addition, the particle transport, deposition, and even entrainment governing equations are solved independently of the fluid flow equations with one-way coupled particle model.
• Numerical methods
The numerical method is a scalable finite volume method with multigrid on structured hexahedron grids, which is used to solve the transient, three-dimensional (3D) and compressible Navier-Stokes equations for multiple gas species [4]. The linearized ICE'd ALE algorithm provides the basis of the computational method to integrate the equations in time and space [4]. More than ten million of cells and particles will be used in the numerical simulation of hydrogen purification and carbon particle filtering through purification system using GASFLOW code.
• Practical relevance of expected results
The expected results consist of the validation of the numerical modeling of solar hydrogen purification in the simulation tool GASFLOW, and the application simulation of the purification system in laboratory scale experimental facility and the relative larger scale demonstration plant. The validated simulation tool provides a reliable method to evaluate the hydrogen purification performance and the further simulation demonstrates the applications and may provide suggestions in the practical design.
• Relevant literature or publications
[1] Innovationspool-Projekt 2021-2023 des FB Energie – Programm MTET Zukunftsthema „Solarer Wasserstoff – hochrein und komprimiert (Solarer Wasserstoff)“, FB Energie – Innovationspool 2021 – 2023: Zukunftsthema „Solarer Wasserstoff“, 15th, May, 2020.
[2] Geißler, T., Abánades, A., Heinzel, A., Mehravaran, K., Müller, G., Rathnam, R.K., Rubbia, C., Salmieri, D., Stoppel, L., Stückrad, S. and Weisenburger, A., 2016. Hydrogen production via methane pyrolysis in a liquid metal bubble column reactor with a packed bed. Chemical Engineering Journal, 299, pp.192-200.
[3] Ohi, J.M., Vanderborgh, N., Consultants, G.V., Ahmed, S. and Kumar, R., 2016. Hydrogen fuel quality specifications for polymer electrolyte fuel cells in road vehicles. Office of Energy Efficiency and Renewable Energy: Washington, DC, USA.
[4] Xiao, J., Breitung, W., Kuznetsov, M., Zhang, H., Travis, J.R., Redlinger, R. and Jordan, T., 2017. GASFLOW-MPI: A new 3-D parallel all-speed CFD code for turbulent dispersion and combustion simulations: Part I: Models, verification and validation. international journal of hydrogen energy, 42(12), pp.8346-8368.