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Proper ISRU/Drill usage


Warzouz
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I'm puzzled with recent heat management and ISRU updates. Here is what I understood, embedded with my doubts :

  • Drill efficiency is modified by having an engineer on board. Further more, engineer level increase the drill output (or reduces energy flow ?) by a lot (x25 compared to a simple probe core)
  • If drills don't receive enough energy flow, they shutdown and need to be manually restarted
  • Drill ore output is constant, but energy consumption depends on ore density
  • Are drills impacted by heat ? How ?
  • If ore tanks are full, drills continue to consume energy (this can be a problem when relying to fuel cells).
  • ISRU efficiency doesn't depends on engineer level, but depends on heat.
  • ISRU have to be cooled down : at what level ? as low as possible or is there a threshold ?
  • What heat impacts ? energy consumption or fuel output ?
  • If ISRU lack energy, it pauses but restart automatically when energy flow is back (no need for manual restart as drills).

Thanks for the insight.

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Here's how it works:

Operating temperature

Both ISRU and drills have an ideal operating "core temperature."  For drills, it's 500K.  For ISRU, it's 1000K.  When they're exactly at that temperature, they're operating at 100% efficiency (more on what this means, in a moment).  If they're at any other temperature-- either hotter or colder-- then they're operating at lower efficiency.

They start out at whatever the ambient temperature of your ship is (usually a lot lower than 500K, so, crappy efficiency).  As they run, they warm up and become more efficient.

You want to have some radiators on your ship to keep them from heating past their max-efficiency temperature.  The good news is that the radiators are intelligent enough that they won't "overcool"-- that is, suppose you have more radiator capacity than you actually need, they won't shoot you in the foot by keeping your drills chilled and running inefficiently.  The radiators are smart enough to say, "I'm not going to cool this drill at all until it gets up to 500K, but then I'll cool it to keep it from getting any hotter than that at all."  So as long as you have enough radiator capacity to do that, you don't have to worry about having "too much"-- it won't hurt you (other than the cost and weight of lugging around the extra radiators).

 

What does "thermal efficiency" actually mean?

It's a multiplier on the operating rate of the drill or ISRU.  A drill running at 100% efficiency is pulling ore at the fastest rate it possibly can.  An ISRU at 100% efficiency is converting ore to propellant at the fastest rate it possibly can.  When the efficiency is, say, 50%, that means that the drill is mining at half speed, or the ISRU is converting at half speed.

 

What about power consumption?

My observation has been that you only pay electricity for actual results.  That is, if your drill is running at 10% thermal efficiency, then you're getting ore at only 1/10th the rate, and you're only using 1/10th the electricity.  In other words, a mining operation spends a certain amount of electricity per ore unit mined, regardless of the thermal efficiency.

What this means in practice is that you start up all your drills, they have really crappy thermal efficiency ('coz they're all cold), and you're using very little electric power.  As they warm up, they start pulling ore faster, and they also start drinking electricity faster.

So basically, the way drill power consumption works is this:

  • A drill that's running at 100% thermal efficiency, and which is actually mining ore because you have empty ore tank space available, pulls 15 EC/second of electricity.
  • It does this regardless of the ore concentration and the engineer skill level.  If the ore is lower, or the engineer level is lower, this means it pulls less ore/second, but it's still pulling the full amount of electricity.
  • Thus, higher ore concentration means less electricity needed per unit of ore.
  • Thus, higher engineer skill means less electricity needed per unit of ore.
  • Thermal efficiency is a multiplier on both the ore rate and the power consumption, so it affects ore-per-second but not electricity-per-ore.
  • You only pay electricity if some conversion is actually taking place.  If your ore tanks fill up and you're not draining them via ISRU, then your drills stop drawing power.  If your LFO tanks fill up so your ISRU can't convert any more, it stops drawing power.  If you're ISRU-converting and ore-drilling at the same time, and you have ore in your tanks but its level is dropping because the ISRU is converting faster than the drills can drill, then the ISRU power consumption will drop a lot when the ore tank reaches zero, because then the ISRU will be throttled to the paltry incomng ore rate from the drills, which is a lower rate.

Ore mining is really really slow, so you want your ore drills running at 100% thermal efficiency.  To do that, all you need to do is 1. make sure you have radiators on the ship, and 2. wait.  The drills will naturally warm up as they operate until they reach optimum operating temperature, and the radiators will then stop the drills from getting too hotter.

As far as ISRU is concerned, it's not worth worrying about, it'll generally take care of itself.  Besides, ISRU capacity is so much higher than drill capacity that it's never a bottleneck-- one ISRU can cheerfully keep up with the output from a dozen drills.

 

What's the practical upshot?

  • Land on good ore concentration, and use a good engineer.  This doesn't just affect the speed of your operation:  it also affects how much electricity-per-resource you need to spend.  So it can make the difference between a ship that runs happily forever, and one that keeps running out of power.
    • Fuel cells are of particular interest.  A mining/ISRU ship turns electricity into LFO.  A fuel cell turns LFO into electricity.  There's a certain break-even point, above which fuel cells generate more electricity than the LFO they consume, and below which they don't.  You really want to be above that break-even point, because it's the only way to keep your rig running through the night.  So make sure you're on a good ore spot, unless you want to shut down each night.
  • Have enough radiators on your ship.  Doesn't need a huge amount of them, but have enough.  If you have more than you need, it doesn't hurt anything.
  • Be aware that your initial power consumption will be a lot lower than your steady-state consumption.  Drills take a long while to warm up, like an hour or so of operation.  They won't be drawing max power until they warm up to 500K.  So after you start drilling, open up the drill's menu, watch the temp, and then timewarp at 10x or 50x until it gets up to 500K.  Now you can see how fast your ship will really mine, and whether it has enough electricity supply.

 

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For cooling, it appears that both the drill and ISRU need significant cooling. I've found that a couple of small heat control panels ("Thermal Control Systems") + a couple of 6-panel solar panels on the adjacent part isn't quite enough to stop an ISRU going over its max operating efficiency. However, it takes a significant amount of time to exceed maximum-efficiency temperature meaningfully.

I don't think there is any need to worry about too much cooling for either of them: the thermal control system shouldn't try to cool the operating "core" directly, but rather the "core" heats up independently and that hot core then heats the part and adjacent parts, and it is the latter that is cooled by the thermal control system.

As for efficiency and power usage: the stated temperature-dependent "efficiency" of the drill and ISRU appears to be merely a question of operating speed. So taking the ISRU, for example, a 100%-efficiency (1000°) core will consume vast amounts of electricity and convert ore correspondingly quickly, while a 10%-efficiency core (can't remember what sort of temperature that corresponds to - maybe 500°?) will consume much less electricity and convert ore slowly. The actual efficiency of the conversion is unchanged.

The engineer affects drill output over time, but the drill operating speed and energy consumption depends on its temperature. Therefore it seems that the one place that you don't want to drill without an engineer is The place where the percentage operating efficiency is most significant is when drilling an asteroid, since it will lose mass as you drill, but this mass will only be converted to ore on your ship at a 1:1 ratio when you're at 100% thermal efficiency. If you run out of ore storage space, the drill simply does nothing at all. Therefore the best way to drill out an asteroid while preserving the maximum amount of mass would probably be to prohibit use of your ore tanks until the drill is up to 100% efficiency, then allow the tanks to be filled. This also means you can happily leave ISRU and drills running together (provided you have sufficient cooling) and be sure that you are obtaining the most efficient output. at the same speed* with or without an engineer, but ore output will vary greatly depending on the presence and level of the engineer.

* (at least this is what it looked like to me the last time I did it. Unfortunately I don't currently have a good way to check the figures)

Edited by Plusck
corrected wrong info after testing
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Well, I'd have to test to be sure, but from experience and memory I would say:

- yes, conversion ratio is fixed. For the big ISRU it is 1:1 mass for LfOx.  Less for monoprop. I haven't touched the small ISRU due to wiki and forum posts about poor conversion ratio.

- energy use is directly proportional to conversion speed. The wiki gives 30 electricity per second for 0.5 ore per second at 100% efficiency, and I have no reason to doubt that.

- conversion speed appears to be directly proportional to % efficiency. I'd have to test but I have no reason to think it is anything other than a percentage of those wiki figures: i.e. 10% efficiency means 3 electricity per second for 0.05 ore...

- % efficiency is an inverse function of the difference between current temperature and 1000°K, apparently as some sort of sine function. Thus, as temperature rises the % efficiency rises very slowly at first, speeds up in the middle range of 30-70% then slows on approaching 100%. Since the part has a 2000°K heat tolerance, I would guess that exact same efficiency function continues above 1000°K (i.e. slow decrease in efficiency in the 1000-1200° range, speeding up afterwards and finally slowing to 0% as it explodes).

Edited by Plusck
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On 5/1/2016 at 0:11 PM, Plusck said:

The engineer affects drill output over time, but the drill operating speed and energy consumption depends on its temperature. Therefore it seems that the one place that you don't want to drill without an engineer is an asteroid, since it will lose mass at the same speed* with or without an engineer, but ore output will vary greatly depending on the presence and level of the engineer.

* (at least this is what it looked like to me the last time I did it. Unfortunately I don't currently have a good way to check the figures)

Ok, well this part of my post is simply flat-out wrong :/

Testing using KER, when drilling out an asteroid, showed that the combined mass of the ship + asteroid was decreasing while the drill operating efficiency was less than 100%. The mass remained constant when the drill was at 100% efficiency, and stayed constant when I sent the engineer out on an EVA.

Therefore it doesn't matter whether you have an engineer on board or not, except in terms of time. The engineer's presence will increase the speed of ore output, but has no effect whatsoever on the efficiency of the drilling operation. When at 100% efficiency, the drill gives a 1:1 "conversion" ratio of drilled resources to ore.

So if you're drilling an asteroid, the one thing you really must do is to drill a maximum amount of ore at one go, since you are losing mass (to space?) during the drill's spinning-up phase.

 

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15 hours ago, Plusck said:

Testing using KER, when drilling out an asteroid, showed that the combined mass of the ship + asteroid was decreasing while the drill operating efficiency was less than 100%. The mass remained constant when the drill was at 100% efficiency, and stayed constant when I sent the engineer out on an EVA.

I was wondering why my Asteroid Munninator redirector/drill ended up with less mass than I expected!

 

You can get around the problem by locking the ore tanks (or leaving them full)

Then, when the drills are started, they will be stalled on ore storage and not actually extract any resources, but they *will* warm up.

Once the drills are up to operating temperature, you can unlock the ore tank and start collecting ore and refining fuel without waste.

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3 hours ago, THX1138 said:

Does mining and refining continue whilst I'm controlling other craft?

Short answer:  Yes and no.

Slightly less short answer:  They're supposed to.  However, there are some complications that can get in the way.

Longer answer:

If all you're doing is mining, just filling up those ore tanks, then yes, it will keep doing that.  Come back after a sufficiently long time and you'll find that all your ore tanks are full.

If all you're doing is refining, just turning ore into fuel, then I believe the answer is yes, it will keep doing that.  Come back after a sufficiently long time and you'll find that all your ore has been converted into fuel, oxidizer, whatever.

So... this is good, right?  Just leave both the ore and the refining going, and you'll come back with full fuel tanks, right?

Alas, no.  As far as I can tell from observing it, the game doesn't seem to have any idea that "A gets turned into B" plus "B gets turned into C" equals "A gets turned into C".  If you leave a mining-and-refining ship alone, what happens is that during your absence, the ore tanks will fill up... but the fuel tanks won't.  Because the code for the refinery just figures "Okay, when you left me and I went on rails, there was just this smidgeon of ore left in the tanks, and I converted that, so I stopped."  It's not smart enough to figure out that ore which is mined in the background while on rails is also available for refining in the background while on rails.

So what this really means is, yes, you can leave it alone and it'll continue to operate as you expect... but only for the duration it takes to fill up the ore tanks, then essentially all work grinds to a halt.

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On 27.01.2016 at 6:13 AM, Snark said:

So what this really means is, yes, you can leave it alone and it'll continue to operate as you expect... but only for the duration it takes to fill up the ore tanks, then essentially all work grinds to a halt.

For a day. It actually updades at the start of the day, so it never really stops, but it will only convert as much as can fit in your ore tanks per day. So if you need to make 3000 fuel and have 1500 ore tank, it will take you 2 days, but if you have only 75 ore tank, you'll need 40 days for same result. If you are controlling your craft same work will only take 30 minutes(if you have enough drills to keep up with ISRU). 

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On 27/01/2016 at 5:13 PM, Snark said:

As far as I can tell from observing it, the game doesn't seem to have any idea that "A gets turned into B" plus "B gets turned into C" equals "A gets turned into C".

1 hour ago, Leftotian said:

So if you need to make 3000 fuel and have 1500 ore tank, it will take you 2 days, but if you have only 75 ore tank, you'll need 40 days for same result.

[rant]
This is all true, and utterly ridiculous. It's also the reason I still haven't used the stock ISRU parts - beyond a quick "yup, it's broken... as expected."

I'm really not sure if this is just the standard poor copy of mod mechanics (I can think of 3 mods that do ISRU better than stock, off the top of my head), or intentionally preventing the player from running efficient operations. Needing an engineer on site to make the thing work properly is equally daft.

The contracts requiring the shipping of large quantities of ore are also stupid - the whole point of ISRU is to produce a product one can use... i.e. fuel.

Did nobody notice that real-world mining operations put the processing plant right next to the mine if possible, to avoid pointless trucking of raw "ore"?

I have been trying to complete one of those "deliver X units of ore to Y" contracts, but I just cannot be arsed. Sure, I could build something to do this, but I can't come up with a design that doesn't scream "why would you do it this way, what are you going to do with all that ore, it's inefficient, dammit".

As 'ore' has zero intrinsic value, moving it about or storing more than a small buffer quantity makes no sense, except perhaps to serve a rather contrived game mechanic.

Can you sell it? eat it? burn it?... no. So why bother storing it at all?

Production rate dependent on ore storage? in a continuous process that doesn't need to store ore for any logical reason? Whut? WHY?
How did anyone think this was a good idea? :confused:
I work on continuous processing plants IRL, and anyone designing a system like this should be taken out back and soundly flogged. Doubly so if working to mass or volume constraints.
[/rant]

Thanks all for the detailed explanation.
OTOH, I think I'll just stick with the simplest one: Stock ISRU sucks hard, enforces micromanagement, and encourages designs that make little sense IRL. Go install some mods, they're just plain better.

 

 

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56 minutes ago, steve_v said:

Production rate dependent on ore storage? in a continuous process that doesn't need to store ore for any logical reason? Whut? WHY?
How did anyone think this was a good idea? :confused:
I work on continuous processing plants IRL, and anyone designing a system like this should be taken out back and soundly flogged. Doubly so if working to mass or volume constraints.

 

The answer to "WHY?" is: bugs, as usual. Nobody really designed it like this. ISRU doesn't have this limitations by design. Production rate dependent on ore storage comes from low refresh rate of distant vessels. Low refresh rate is there to improve bad performance of the game not to lower converter output. It's an unintended consequence of two unrelated systems not working properly together, basicly a bug. 

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Having too many radiators does hurt. If you have too many it starts to reduce the heat and you are below max efficiency. You want the exact max. If you are above or below it is the same. Or did they change this recently.

 

And none of the values are fixed. If you are at 50% efficiency you are changing 50% of the max ore into 50% of the given item. Ore input to output is always the same ratio. The electricity should always be the same to this also. I believe the only difference is which ISRU you are using. The big one is more efficient than the small one. The point in mining is to get the exact heat needs and then keep the electricity going while trying to get max out put(This only reduce via fuel cells). Anything besides fuel cells only lose you time(Besides the small ISRU's inefficiency that is). Fuel cells reduce actual final output a small amount. Matters for asteroids long term but not for planets.

Overheating only happens when it gets so far above optimal. It is a cap. If you are between optimal(100k or whatever it lists) then it stop at the value it can hold the heat for. and it will change your max output etc based on how far off optimal it is. If you are above it reduces and if you are below it reduces it. The only other thing affecting it is while it still heating up or cooling down. That or adding something to the max heat for the ship and overwhelming the radiators. You have to target the correct heat output. The rest is figuring out if you have enough input and electricity. It takes a tone of Drills to meat one 250 ISRU. I have 8 of them on a ship with one big ISRU and barely dent it. Which gets into which type of refining setup. You can collect large ammounts and refine with lots of ISRU or even the input to output or a few other things possibly. Depends on the desired outcome and the vessels purpose.

It's a bit late and I'm tired so I'm not sure how clear this is. But if you get too much thermal it will go back below optimal heat and reduce your max output again. Just as if you never cooled it enough.

 

Edited by Arugela
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