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How did I break my AETN?


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So I'm fairly new to ONI, been playing only for a few weeks (but a lot in that time, this game is addictive!). I've never gotten too far with my bases, I keep restarting them after learning about something else I should have been keeping track of...

Anyway, my latest map had a cool steam geyser and an AETN fairly close together. I thought I would try my hand at making my first SPOM and have it cooled by the AETN. Here it is:

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AETN.jpg?raw=1

Overlays:

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AETN%20-%20Ventilation.jpg?raw=1

Note: In hindsight I should have made the ventilation pipe that goes to the high pressure vent and storage instead come from the white input of the bridge, so that it would only be used when the generator pipes were full. Then I wouldn't have needed the automated gas valve.

AETN%20-%20Plumbing.jpg?raw=1

As I said, water is coming from Cool Steam Geyser, so it's pretty hot.

AETN%20-%20Gas.jpg?raw=1

The top 2 Atmo Sensors are on an AND gate and control the top pump, on at >300.
Bottom 3 Atmo Sensors control the left pump, middle 2 pumps, and right pump respectively. Left/Right are set to >300, Middles are >0 when electrolyzers are working full time. The clock sensor controls them though and allows me to choose when to run them.

However, once it started, the AETN was only getting the oxygen down to mid 70sF. It started heating up even more after that. Now it's almost up to 100F in there:

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AETN%20-%20Heat.jpg?raw=1

So what did I do wrong that made the AETN not want to cool anything? Is it too close to the hot biomes (which I stupidly got rid of the Abyssalite insulation between them because I didn't know any better) or are my pumps and all that too close to the AETN? Or something else I missed or got wrong?

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I think there may be some gas routing problem with the Hydrogen feed to the ATEN. It may just not get the 70g/s it needs to operate continuously.

As to insulation, use a double layer for insulated tile for a pre-space good approximation of perfect insulation.

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An AETN eliminates 80 kDTU/s. If you're cooling steam from 110 C to 95 C to condense it only, that's 80k / (15 C * 4.179 DTU/g) = 1,276 grams / second. Whether your AETN can keep up with that depends on the geyser; the one on my map emits over 4,000 g/s. I'm not sure what the average output is, including downtime and dormancy, but it's still high enough to be pretty rough on the AETN.

It's worse if you're cooling the water below 95 C. It's often a good idea to just barely cool the steam, and then use the very hot water for something where the temperature's not so important, like an electrolyzer. If you must get the temperature down to 25 C for crops, an AETN isn't nearly enough.

The short version is that AETN's aren't really that powerful. They're like 6.5 Wheezeworts.  Kinda helpful for small tasks when you don't have anything better, but not really up to doing anything major.

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1 hour ago, bleeter6 said:

Your water has MUCH more heat than the AETN can handle. You need to insulate those liquid pipes and then completely seal off the room so no external heat can enter aside from the gas pipes.

I thought based off the wiki (https://oxygennotincluded.gamepedia.com/Electrolyzer) under Heat Economy that it said it was better to send in hot water to the electrolyzers. Is that no longer the case? Or is this water too hot even for that? If so, what would be the best way to cool it before electrolyzing it?

1 hour ago, Gus Smedstad said:

An AETN eliminates 80 kDTU/s. If you're cooling steam from 110 C to 95 C to condense it only, that's 80k / (15 C * 4.179 DTU/g) = 1,276 grams / second.

I let the steam naturally cool into water, although the water was still really hot.

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15 minutes ago, KAJ3D said:

I thought based off the wiki (https://oxygennotincluded.gamepedia.com/Electrolyzer) under Heat Economy that it said it was better to send in hot water to the electrolyzers. Is that no longer the case? Or is this water too hot even for that? If so, what would be the best way to cool it before electrolyzing it?

The Electrolyzer's output is always 70* (or higher, if the input reagent's temperature is higher). That means if you're electrolyzing for cool oxygen (or Hydrogen) from water that's cooler than 70*, you're creating "extra" heat to process.

Elecroly.png

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1 hour ago, KAJ3D said:

Is that no longer the case? Or is this water too hot even for that? If so, what would be the best way to cool it before electrolyzing it?

There's no too hot water any water will do quite the same thing (e.g. 85C water will produce 85C gases), You don't have to cool the water just condense the steam and done there's a few case that you need to cool it (pool for pacu, farm, toilet, research?)

The point is liquid pipe wasn't insulated so it constantly drawing cooling potential from AETN and by routing it through metal door would make it draw faster so you're cooling a water and then send it to electrolyte Which is not a good thing.

And BTW you don't have to cool hydrogen as it will get destroyed anyway.

In short : Just slap all insulated liquid/gas pipe into your room except oxygen pipe inside AETN and isolate the room from outside by removing locked door and replace it with insulated tiles, Polluted water lock can be replaced by vacuum door.

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2 hours ago, KAJ3D said:

I thought based off the wiki (https://oxygennotincluded.gamepedia.com/Electrolyzer) under Heat Economy that it said it was better to send in hot water to the electrolyzers. Is that no longer the case? Or is this water too hot even for that? If so, what would be the best way to cool it before electrolyzing it?

I let the steam naturally cool into water, although the water was still really hot.

Your hot water in the pipes is heating up the AETN. Just do what I suggested and the problem is solved. It has nothing to do with the electrolyzer.

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15 hours ago, KAJ3D said:

Anyway, my latest map had a cool steam geyser and an AETN fairly close together. I thought I would try my hand at making my first SPOM and have it cooled by the AETN.

As others have posted above, the AETN can only remove about 80k DTU of thermal energy.  The amount of thermal energy an object contains is dependent on its mass, the thermal properties OF that mass, and its current overall temperature.  

Lets say you have a 1 cm3 object.  In case one, it is a mass of 1g.  In another case, that mass is 10g.  If all other properties are the same, the first 1cm3 object will hold 1/10th the thermal energy of the second.

Now lets pretend that both objects are identical both in mass and thermal properties.  If one is at 1C, and the other at 10C, then the first holds 1/10th of the thermal energy of the second.

Third, lets pretend that the objects contain the same amount of matter, and are of the same temperature, but one has a Specific Heat Capacity of 1 and the other has a SHC of 10.  The first will have 1/10th of the thermal energy of the second.

OK, now lets take these principles and apply them to your AETN.  We're going to ignore the mass of the AETN, as well as the hydrogen surrounding it because the only thing we want to look at is the change in thermal energy.

image.png.877dea9facb85080152c61b5541e8291.png

In this little image, we see that there are tiles under the AETN that are not insulated.  We also see that there is a heavi-watt joint plate -- made of metal that conducts.  So, the heat from your machine below is entering your AETN chamber.

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I assume that this shot shows what you're intending to cool down -- the oxygen in radiant piping.

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This shot shows where your heat is all coming from.  However, lets instead pretend that you have insulated the tiles under the AETN such that the ONLY heat entering your room is via the radiant gas pipes.  Here's how its working:

Lets assume that both electrolyzers are running continually.  That means that they're continually receiving 1kg/s of water each and turning it into 112g/s of hydrogen and 888g/s of oxygen.  For the sake of simplifying matters, lets assume that the water is 70c and arriving through insulated piping.  This means that the water itself won't be affecting the system in our little model.  

888g/s of oxygen at 70c holds 1.005*888 = 892.44 DTU/oC/s of thermal energy.  112g/s of hydrogen holds 2.4*112 = 268.8 DTU/oC/s.  Combined, they total 1161.24 DTU/oC/s of thermal energy.  We're going to ignore the heat added by the operation of the gas pumps and the electrolyzers -- though this is significant -- and just use the produced materials alone.  

Lets start with the oxygen, since that is what you're intending to cool.  At 892.44 DTU/oC, if it is produced at 70c and your target is 20c, then you're adding 892.44*50 = 44622 DTU/s of thermal energy to your AETN -- a little over half of its capability.  In other words, it should be cooling the oxygen down with no problems.

For now, lets ignore your wheezewarts that are clearly placed to cool the hydrogen.  Since it goes through the room in a regular pipe (not insulated), it is exchanging energy with the room.  In fact, it is adding 13440 DTU/s.  So now we're up to a total of 58k DTU/s, which is still lower than the 80k DTU/s your AETN can cool. We ought to be good.

OK, now lets add in the room below, since it isn't isolated by insulation.  First, lets look at the piped water, since the pipes aren't insulated they will be trading thermal energy with the rest of the room.  Lets assume your water is at 70c.  Water holds 4.179 DTU/g/oC of thermal energy.  The electrolyzers are using 2kg/s total, so that means that you're piping in 4.179 * 2000 * 50 = 417.9k DTU/s of thermal energy.  This is 338k DTU/s more than your AETN can handle.  And we haven't even gotten to the heat generated by the operation of the buildings themselves.

There is yet one more little problem I noticed with your current build.

image.png.e912ca42b02fe316c99a85dbc6a6560d.png

Right here we see that your hydrogen gets split onto the pipe from the gas pump so that one side goes to the AETN and the other goes to storage/use/whatever.  You have only a single pipe segment that can hold hydrogen.  There is the possibility that your AETN doesn't have 100% up time, depending on your oxygen use.  A longer segment of pipe would guarantee that your AETN never runs out of fuel.

 

Anyway, in conclusion:
You need to insulate the tiles under the AETN to reduce the thermal energy entering from your oxygen supply machinery.  You also need to insulate the water pipes (at least where they go through the AETN room) so that the thermal energy from the water isn't being added.  Finally, you need a longer pipe segment to the AETN to guarantee that it runs continually.

 

@KAJ3D your design looks great and with a few tweaks it will probably do exactly what you want it to.

 

*** EDIT: Oops! I made a significant error.  I forgot to multiply by TWO.  Each electrolyzer produces 112g/s of hydrogen and 888g/s of oxygen.  Assuming that both are running continually, this is 224g/s of hydrogen and 1776g/s of oxygen.  This means that if you're cooling both the oxygen and hydrogen (as neither pipes are insulated when passing by your AETN), then you need 116k DTU/s of cooling, 36k DTU/s more than your AETN can provide.  Assuming you need to cool from 70c down to 20c, your AETN alone can't cut it.  If the temperature margins are smaller, say cooling from 50c to 20c, then your AETN can keep up.

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Thanks everyone for your helpful comments. I thought about trying to fix this one up, but ultimately decided to restart using the same map seed. This wasn't the only thing on this map I messed up and with hindsight I think I can do it all again better.

(BTW, the hydrogen pipes and the heavi-wire plates were because I was originally storing my smart batteries in the same room as the AETN, and I was trying to use the hydrogen to cool the batteries... it was obviously a bad idea. I moved the wheezeworts in there after I removed the batteries but never got rid of the pipes or the wire plates)

Anyway so for my next attempt, I need to:

- Fully insulate the AETN: remove the original flooring, either double insulation walls or vacuum walls, and airlock vacuum doors

- Not have any piping/power go through the AETN except for my oxygen I want cooled, especially not hot water, also insulate the water pipes

- Move the SPOM a few tiles away, and give it the same level of insulation the AETN has (has the added benefit of extended the hydrogen piping that feeds the AETN so it won't be starved)

Oh, one more question, the hydrogen in the AETN room. Right now I have it 20kg because of the high pressure vent, is that needed or helpful (instead of regular vent)?

Thanks again!

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1 hour ago, KAJ3D said:

Right now I have it 20kg because of the high pressure vent, is that needed or helpful (instead of regular vent)?

The AETN doesn't care what is filling the chamber. It just removes a fixed heat value. Any gas or fluid will work as a medium. Hydrogen is a common choice, but oxygen or polluted water will work as well. The problem with polluted water is of course that it's going to freeze, and the gasses won't.

Medium does matter with Wheezeworts, because those don't use heat values, they straight lower the temperature of the gas they pump, regardless of specific heat of the gas. So gasses with higher specific heat get cooled more. Again, hydrogen is the choice because of its high specific heat.

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36 minutes ago, Gus Smedstad said:

The AETN doesn't care what is filling the chamber. It just removes a fixed heat value. Any gas or fluid will work as a medium. Hydrogen is a common choice, but oxygen or polluted water will work as well. The problem with polluted water is of course that it's going to freeze, and the gasses won't.

Medium does matter with Wheezeworts, because those don't use heat values, they straight lower the temperature of the gas they pump, regardless of specific heat of the gas. So gasses with higher specific heat get cooled more. Again, hydrogen is the choice because of its high specific heat.

I wasn't referring to which element, I was referring to whether it should be high pressure, or if regular pressure does just as well. It took a while to fill the whole thing with high pressure hydrogen and if there's no benefit to doing that over regular pressure, then I'd rather just save the hassle for next time.

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52 minutes ago, KAJ3D said:

I wasn't referring to which element, I was referring to whether it should be high pressure, or if regular pressure does just as well. It took a while to fill the whole thing with high pressure hydrogen and if there's no benefit to doing that over regular pressure, then I'd rather just save the hassle for next time.

The same thing applies essentially. Wheezeworts will lower the temperature of the gas by 5C. If there's more gas, more heat is removed.

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Don't attempt to cool down scalding water. Water is one of the best natural heat sponges in the game and the amount of effort required is endgame difficulty. Instead, pump the hot water directly into electolyzers instead. The extra hot hydrogen can be burned right away, and the 95C oxygen output is incredibly easy to cool down with an AETN..

Worts don't use the kDTU system. They absorb the gas and respawn it 5C colder. Hydrogen is the most effective since 5C hydrogen is much more energy than 5C oxygen.

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2 hours ago, KAJ3D said:

I wasn't referring to which element, I was referring to whether it should be high pressure, or if regular pressure does just as well.

Sorry, I should have been clearer. I started by saying "it doesn't matter what you use to fill the AETN chamber" and forgot to mention that largely covers pressure / density as well. Only at very low pressures is it going to matter, as the temperature will drop very rapidly if the total mass is low.

Let's say you've got hydrogen at 1 kg / tile, covering 20 tiles. That's 20 kg * 2.4 DTU/g/C = 48 kDTU/C. So 80k DTU/s drops the temperature 80/48 = 1.67 degrees per second if nothing else is going  on. This only really matters if you bottom out at -173 C, where the AETN stops cooling.

It's pretty common to wallpaper AETNs with granite tempshift plates, just for their thermal mass. That's actually far, far more effective than pumping in 20kg / tile of hydrogen, provided there's any gas in the room at all.

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5 hours ago, KAJ3D said:

Oh, one more question, the hydrogen in the AETN room. Right now I have it 20kg because of the high pressure vent, is that needed or helpful (instead of regular vent)?

Thanks again!

Having more mass at the temperature you want will stabilize the system overall.  The more mass, the less variation will happen to the temperature.  So, 20kg/tile of hydrogen will be more stable than 1kg/tile.  Though, for it to mean anything, you'll need a way to shut the AETN off when the room's ambient temperature is at the point where the oxygen leaving the room is at the temperature you desire.  

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I've seen the door under the AETN trick to shut it down, but it feels kind of exploity.. could I use a gas valve attached to a thermometer? 

Also, would it better to fill the room with hydrogen and get the AETN cooling properly before I start sending in oxygen? Basically to make sure I'm not trying to cool the room and the oxygen at the same time?

I'm also going to leave out the wheezeworts so I don't have to leave access to the room. Hopefully the firepower of a fully armed and operational AETN will be enough cooling for me.

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I've used a gas valve to shut down an AETN. It's rather delayed, because the AETN only eats hydrogen at 10 g/s. So if you have two pipe segments between the valve and the input, that's 2 kg = 200 seconds of operation after the valve shuts off.

In practice, I've always found that whatever heat load I was trying to cool was too much for the AETN. Just as you did in your original message. So shutting down the AETN wasn't so important.

Something I used to do with wheezworts might be helpful to you, if you ever do find yourself in that situation. Wheezeworts can't be deliberately shut down, though they do shut down by themselves at -60 C. I'd build a room over my target room - generally a cool steam vent - with a metal plate at the base, and airlock doors acting as heat conductors between the metal floor and the target room. I'd automate it so if I wanted cooling, the doors were closed and conducting heat, and if I didn't, they'd open and act as insulators.

You could do the same sort of thing with an AETN, leaving it on all the time, and using doors as heat conductors to the room where your target (such as air vents) got cooled.

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3 hours ago, Gus Smedstad said:

I've used a gas valve to shut down an AETN. It's rather delayed, because the AETN only eats hydrogen at 10 g/s. So if you have two pipe segments between the valve and the input, that's 2 kg = 200 seconds of operation after the valve shuts off.

If you care, put in a gas valve before and limit flow to 10g/sec. On the other hand, the ATEN is pretty much slow to react thermally due to its mass anyways.

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The problem with a valve -> shutoff setup is that when the shutoff is turned off, gas or fluid continues to flow from the valve to the shutoff. With enough time, you end up with 2 full pipe segments between the shutoff and the valve. 2kg of hydrogen in this case. When the shutoff opens again, all of that moves into the pipe between the shutoff and the AETN, and only gets consumed at 10g/s. When the shutoff closes again, you still end up with a 200 second buffer of hydrogen.

The valve does help if the shutoff is open more than 50% of the time, and no shutoff period is 200 seconds or more.

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I've had this problem myself long ago. I remember reading about it somewhere and someone suggested dealing with this problem by using a simple mechanical filter.

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sytXe3sn.png

The gas valve is set to 990 g/s.

With this, the AETN will only ever get 10 g/s when the shutoff is turned on.

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1 hour ago, Leonard_ said:

With this, the AETN will only ever get 10 g/s when the shutoff is turned on.

That's brilliant. I would never have thought to invert the gas valve that way, so only the 10 g/s dregs can make it to the shutoff valve.

I deal with a similar problem every time I set up a water drip system to prime my steam turbines. You don't want to feed too much water into one of those, because every kg you add slows down the initial transition from water to steam. I'm not sure the extra mechanics are worth the effort in that particular case, but it's nice to know there is a solution to the restricted flow valve -> shutoff problem.

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Good news everyone!

With everyone's wonderful advice, I was able to get it up and running and cooling super effectively:

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New%20AETN.jpg?raw=1

Learned my lesson last time and didn't unearth the gold volcano to the left (not yet anyway). Also kept as much of the cold Abyssalite as I could. Finally I insulated the steam vent so it wouldn't spread so much heat.

New%20AETN%20-%20Vents.jpg?raw=1

I also 'primed' the AETN with a hydrogen vent (from halfway across the map...) so that it was both full in the room and running for a while while I was building the SPOM. I did that so it would cool down the ridiculously hot ceramic insulation and diamond tempshift plates before I sent hot air in through the pipes. 

New%20AETN%20-%20Pipes.jpg?raw=1

Insulated pipes! What a concept!!

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Yeah we discussed the limitations of the gas shutoff valve. But it was the easiest way to do it, so we'll see how it goes.

New%20AETN%20-%20Heat.jpg?raw=1

So frosty!!

Thanks again everyone!

Now to tame that volcano...

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