Scaling up and optimization of hydrogen compressor and storage systems using simulation software
Sector: Energy supplySpecialist field: Fluid mechanicsAccelerated large-scale implementation of green hydrogen is seen as a prerequisite for the transition to clean energy and the achievement of the net-zero emissions target in the energy and transportation sectors. GRZ Technologies has pioneered the commercialization of solid-state (metal-hydride) hydrogen systems, which enable safe, compact, and efficient compression and storage of hydrogen. These types of systems are thermally controlled, and, as they grow in size, proper thermal design becomes paramount to their performance and storage capacity. For this purpose, GRZ Technologies chose ANSYS FLUENT to optimize the 3-D flow and thermal characteristics for all products in its portfolio.
Summary
Task
For the case of hydrogen compressors, the performance is mainly quantified in terms of compression ratio, storage capacity and hydrogen flow rate. The fundamental challenge involves the specification of the design parameters and operating conditions to meet the strict requirements for fast hydrogen compression and delivery.
Solution
Ansys FLUENT software was used to perform a coupled fluid dynamics-heat transfer simulation of the thermal hydrogen compressor. With the understanding of the underlying complex physical phenomenon, optimum design and process parameters are determined.
Customer benefits
The use of Ansys FLUENT enabled efficient optimization of the design and operating conditions, which reduced the manufacturing and operating costs for the operation of the compressor. At the same time, the product development cycle is minimized since several geometries can be evaluated numerically.
Project Details
Task
The hydrogen absorption/desorption behavior is highly dependent on the temperature distribution within the metal hydride. Cylindrical cells contain the metal hydride material, which is in powder form. Several such cells are placed in a “shell-and-tube heat exchanger” type of arrangement within a bigger cylindrical container to form the overall compressor system. The thermal management of such a system is commonly done through the circulation of a thermal medium, such as water, steam, air or any other medium at accurately controlled thermal and flow conditions to provide the required heating or cooling power. GRZ technologies has developed a numerical procedure to simulate a range of systems using ANSYS Fluent and in-house developed models. The compressor or storage geometry is modeled parametrically, meshed and simulated. The spatial distribution of temperature and flow field are obtained from the numerical simulation (see Figure 1) for the case of an industrial-scale hydrogen compressor. The thermal medium flow velocity and distribution plays an important role in determining the temperature distribution within the metal hydride and eventually the compressor’s performance. Using the parametric model, various options for reducing manufacturing and operating costs can be explored, while achieving the required hydrogen delivery pressure, flow rate and capacity.
Customer Benefit
With Ansys Fluent, GRZ technologies was able to establish a versatile and robust numerical process for evaluation of the design of a metal hydride-based hydrogen system. This drastically reduces the development cycle of new products by enabling the targeted optimization of relevant design and operating parameters. Ultimately, the detailed insights obtained through numerical simulations allow significant reduction in manufacturing and operating costs of the developed systems. In addition, it provides a solid foundation for the development and refinement of various reduced-order computationally efficient models.
Solution
The numerical method described above can be used for many thermal and chemical technologies with similar physics. With Ansys Fluent, the thermal compression process is simulated, and the relevant evaluation parameters are quantified. The numerical results are interpreted based on the evaluation parameters defined, e.g., the maximum metal hydride temperature (see Figure 2), and an appropriate course of action is determined to optimize the design. The coolant flow path is optimized by varying design parameters (e.g., tube arrangement) to improve performance (e.g., minimize pumping power) while maintaining certain requirements (e.g., minimum temperature non-uniformities). After achieving the optimum design, the operating limits (e.g., coolant flow rates) of the compressor are determined where the target compression rates are achieved. Novel mathematical models describing the thermal compression and storage processes can also be tested and evaluated.
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