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Cake day: 2023年6月14日

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  • Oh neat, I actually know a lot about hydrogen-natural gas blends!

    I read the report because of this claim:

    And now, a team of British researchers has found adding hydrogen to natural gas actually increases how much natural gas leaks from stove burners and boilers because the smaller hydrogen molecules help the larger methane ones escape.

    I’ve never heard of small hydrogen molecules helping larger molecules leak. I was curious what the mechanism for this was. It turns out the report does not make that claim at all. In fact, the report claims the additional leakage from hydrogen blends is most likely just the hydrogen leaking. I didn’t run the numbers myself but the data presented seems approximately aligned with that. Hydrogen leaking through fittings is already a well-known and established challenge of blending hydrogen with natural gas. So the central thesis of this news article is completely fabricated.

    I am a little surprised the utility companies are going to soon be mixing in hydrogen. I didn’t think we we’re quite ready to blend in hydrogen into natural gas for the leakage reason, and also because of production scaling issues that we haven’t resolved yet. These challenges are likely within reach soon. For example, the United States department of energy has a large research initiative right now to help lower the cost of hydrogen production to be more competitive with natural gas. We also need to make sure that hydrogen is produced in a carbon-free or carbon neutral way, which is probably going to be dependent upon our electrical grid becoming carbon free.


  • Nebulizer@lemmy.worldtoLinux@lemmy.mlbest foss cad software?
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    8 个月前

    I’ve been using SALOME to create parametric 3D geometry. My use case is to parameterize my geometry features and export to STL files that I use with OpenFOAM. SALOME is integrated with a couple of grid generators, and I really like it’s 2D/triangulation/STL integration with netgen. You can specify faces for refinement to a desired mesh size, so for example around complex features you can create a fine STL mesh and on simple shapes you can have a really coarse mesh.

    I’ve found the 3D modeling to be pretty straightforward, and SALOME usually does a pretty good job if you have to go back and modify previous features (something I’ve struggled with in FreeCAD).

    I’ve also used FreeCAD for mesh generation, and it works ok but I’ve found the triangulation leaves a lot to be desired for splitting up the mesh as needed for OpenFOAM boundaries.

    If you’re making STL files for 3D printing and you want a parametric CAD modeler for engineering parts, give it a try. If you want complex faces with artistic style, I would suggest Blender.