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Dutch manufacturer develops sustainable 700-bar filling technique for future hydrogen cars

Discussion in 'Fuel Cell Vehicles' started by usbseawolf2000, Apr 7, 2015.

  1. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Why 700 bar? Hydrogen has a lower energy content than natural gas, which means that the same volume contains less energy, one-third that of natural gas to be precise. Refuelling hydrogen at a higher pressure (700 bar or about 10,000 psi) supplies enough energy to give a hydrogen car a respectable range. The hydrogen cylinder will have to be filled to 700 bar within 3 minutes, because most consumers will not wait longer than that at the filling station.

    Of course, there are problems. The crux is that when filling hydrogen gas at high speed, the gas expands when it becomes hot. Currently the solution for this problem is to pre-cool the hydrogen gas, but this inefficient method results in unnecessary loss of energy.

    The Teesing solution for 700 bar is a system counteracts the expansion. The cylinder is first filled with water at a pressure of 700 bar, after which the water is displaced by introducing hydrogen gas at the pressure. Prototypes have been tested successfully and a patent has been issued for the PusH principle.

    Hence, no expansion, no heating, less energy loss and it is still possible to fill up fuel cell vehicles quickly up to 700 bar. The method has the additional advantage that no extra action is required to moisten the hydrogen. Fuel cells function more efficiently if the hydrogen has been moistened.

    Dutch manufacturer develops sustainable 700-bar filling technique for future hydrogen cars
     
  2. wjtracy

    wjtracy Senior Member

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    There are a lot of new H2 technologies being developed for FCV...I am quite excited about it too.
     
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  3. usbseawolf2000

    usbseawolf2000 HSD PhD

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    I really like this technique. I wonder how long it would take to fill H2 tank with water at 700-bar. This has to be done before H2 fill up.

    How about filling up with half H2 left?
     
  4. Trollbait

    Trollbait It's a D&D thing

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    Well, there will always be some hydrogen left, so adding water shouldn't be an issue to a partial tank. At least nothing potentially dangerous or harmful. Some of the tank hydrogen could be lost by dissolving into the water, but I think the water used in the system would soon become saturated with it, so any loss would be tiny.
     
  5. Jeff N

    Jeff N The answer is 0042

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    If there is any water left in the tank after filling then you have to worry about freezing. Freezing water expands which could increase the H2 pressure. A more likely problem is frozen water that plugs up the gas flow or interferes with any valves or pressure regulators in the line leading to the fuel cells.
     
  6. Trollbait

    Trollbait It's a D&D thing

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    A little bit of water left in the tank won't increase the pressure enough to worry about if it freezes. The Mirai tanks are actually rated to 85MPa.

    Freezing in the fuel line is a real concern. This system leaves the hydrogen humidified. As it leaves the tank, it steps down in pressure. The fuel lines are likely going to be metal to contain the contain, albeit lower, pressure. The expanding hydrogen will cool the line, possibly to freezing. It it doesn't, winter temps will do so. Then the resulting frost could build up enough to block the pipe.

    The fix is simple though. Heat the lines, use plastic materials that are non heat conductive, or lines of a large enough diameter that any frost build up won't impede the line. Pressure regulators and valves will likely need heating like diesel fuel filters.

    It will require alterations to current tank design; there needs to be a dip tube at least to allow the water to be squeezed out. This is another example on why CARB pressing for comercialization is premature.
     
  7. austingreen

    austingreen Senior Member

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    lol. Remember when CARB decided all gas stations in california needed to use mbte, before it was tested on the storage tanks. And the tanks leaked, and it got into the water table, and created a huge hazard. No one at CARB got fired over that. They got to increase the staff and a bigger budget to clean up the mess they made. Now do you really think CARB as part of the California Fuel Cell Partnership (known as the leaders of the fuel cell lobby) really cares if they have tax payers buy bad technology?
    Why California mandated poison in your tank
    Carb like the honey badger don't care. They get bigger staff and more money to do anything. Hell this is only another $220M, plus maybe $30K per car on a really small number of cars, pretty small compared to the over $3B already spent on fuel cells.by the federal government.
     
    #7 austingreen, Apr 8, 2015
    Last edited: Apr 8, 2015
  8. Gerben

    Gerben New Member

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    Expanding hydrogen heats up rather than cools, that's one of the weird properties of hydrogen.

    The shut-off valve will indeed require some kind of heating system if you want to start the fuel cell in freezing temperatures.

    Correct
     
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  9. Trollbait

    Trollbait It's a D&D thing

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    Thanks for the info.