Electrolyzer Hydrogen Output

[Gurgel]

I have tried to turn 3kg/sec of saltwater into electricity by venting the Oxygen directly to space and only capturing the hydrogen. However, I get consistently low Hydrogen numbers at around 75% of what I should see. Does not seem to matter whether I feed 1kg packets to 8 electrolyzers (i.e. run them partially) or fully supply just 3 of them. A picture of the setup is below, here with just 3 electrolyzers.

Things I have (mostly) ruled out: Loss to space (there is some, but not that much), not enough water going in (it is pretty much exactly 2.8kg/sec consumed, producing 250g/sec of H2).

Has anybody made any measures how much hydrogen  Electolyzers actually produce? Because it seems to 85...90g/sec instead of the advertized 112g/sec per kg of water used.

 

[OxCD]

12 minutes ago, Gurgel said:

Has anybody made any measures how much hydrogen  Electolyzers actually produce? Because it seems to 85...90g/sec instead of the advertized 112g/sec per kg of water used.

Since the matter duplication bug has been solved, the matter deletion bug has appear (or has been put in place, to avoid the first one, only devs know). I do not have measurement to bring you, but your numbers fit quite well the feeling I have. Unfortunately, until this mechanism is solved (if it is, some day), only drowned electrolyzer will produce the expected 112g/sec.

Or maybe, using a fast bead-pump can help, but not sure, really.

[Angpaur]

41 minutes ago, OxCD said:

Unfortunately, until this mechanism is solved (if it is, some day), only drowned electrolyzer will produce the expected 112g/sec.

This is not exactly true. Hydrogen gets deleted in builds where is a lot of space. Small, compact builds don't delete it. For example below is 100% uptime and produces 112g/s:

[Enzium]

I noticed a significant difference once I put two tiles above the Electrolyzers with one gap in between the two tiles and the electrolyzer. No idea why, but that's the only way I was able to make them selfpowered. Maybe you should try that?

[Gurgel]

Ok, thanks for the confirmation that the Electrolyzer numbers are actually correct. Made me modify the experiment. It turns out it was loss to space. As it seems, you cannot just look at the matter overlay and realistically estimate loss to space. I should probably have known better.

I have now set the eletrolyzers 2 tiles higher in the structure and I get 2.65kg/s water consumed and 300g/s Oxygen produced now, which matches the expected numbers.

Apparently, this is _very_ sensitive to how much distance there is to space below were the Oxygen gets vented. 4 tiles cause significant loss of Hydrogen. 5 tiles and 6 tiles seem to work. 7 tiles seem to cause too much overpressure. That is with 3 electrolyzers spread horizontally over 17 tiles. Other configurations and horizontal sizes may well behave differently. I think I will optimize this some more and then post a configuration that works well. 

[SamLogan]

11 hours ago, Angpaur said:

This is not exactly true. Hydrogen gets deleted in builds where is a lot of space. Small, compact builds don't delete it. For example below is 100% uptime and produces 112g/s:

This is not exactly true. This one destroy hydrogen :

[Angpaur]

Does it change the fact that you don't need to use liquid over electrolyzer exploit to get 100% uptime build that doesn't delete hydrogen?

[Gurgel]

4 hours ago, Angpaur said:

Does it change the fact that you don't need to use liquid over electrolyzer exploit to get 100% uptime build that doesn't delete hydrogen?

I now have a 95% uptime built with < 5% hydrogen loss (may be no loss at all, but measuring this is a pain) and without using liquid. And I am still optimizing. The trick seems to be to have the Oxygen-Hydrogen boundary around the head of the electrolyzers, then the gases get added to tiles that already have the same gas in. I probably should check where exactly the two gases get ejected.

 

[KittenIsAGeek]

On 1/14/2020 at 1:31 AM, Gurgel said:

Has anybody made any measures how much hydrogen  Electolyzers actually produce? Because it seems to 85...90g/sec instead of the advertized 112g/sec per kg of water used.

In my opinion, the problem here would be pressures at the electrolyzer.  You have too much room for oxygen buildup at the top of the electrolyzer.  There's a forum post somewhere that has a couple dozen different ways of arranging gas pumps and electrolyzers and calculations of the output.  @Angpaur's build seems to be the best for getting a correct ratio.  @SamLogan's build shows that too compact causes problems as well.  I've been using variations on the following setup for some time as it gives a guaranteed output of 1000g/s oxygen without needing a filter while still being fairly compact:

 

I see from further posts that you changed your design to bring the hydrogen closer to the top of the electrolyzers.

10 hours ago, Gurgel said:

I now have a 95% uptime built with < 5% hydrogen loss (may be no loss at all, but measuring this is a pain) and without using liquid.

It has been my experience that without liquid, you will have a very difficult time getting a single electrolyzer to 100% uptime.  This is because immediately following an output tick, the electrolyzer may detect its own output as being above the output threshold and thus produce no output during the next tick.  At near vacuum, this happens rarely -- but it still happens.  Liquids "trick" the electrolyzer, because it always senses a pressure lower than its threshold, so always outputs.

[Gurgel]

5 hours ago, KittenIsAGeek said:

 I've been using variations on the following setup for some time as it gives a guaranteed output of 1000g/s oxygen without needing a filter while still being fairly compact.

If you want to make oxygen, you can pump that out, no problem. But if you want to generate electricity, the oxygen is just waste that gets in the way. The last thing you want to do is waste electricity for pumping it. 

95% uptime is entirely fine with me. I am currently optimizing the geometry, not the output.