Need help on a design

[OxCD]

Hi all

I'm working on a design but I still have an issue I do not understand very well.

Here is part of it :

 

This room is perfectly insulated, full of hydrogen, and some water on the floor, coming from the ice melting on the rail. This water also help to keep spreading average t° across ice-makers and temp sensor.

On the other side of the petrol lock, it's vacuum.

This is only a part of a full design, but the other part have no incidence on this one.

How it should work : water at 90° approx is loaded by dupes inside the ice-maker.

Those should move water t° from 90° to -20°. Its spread 80% of this heat removal, and delete 20%. At least that's how they should work, as far as I know.

The ice is swept into the loader. Rails are going through metal floor, then return to the conveyor output, then go again through the floor, and so on. It's a loop. The conveyor will not load more ice until there's some space made on the loop.

If the temp sensor on the floor is above 0°, the loop is closed and the ice stays on the room. If the temp sensor is below 0°, the ice is moved to another part of the setup.

If there's more than 10kg water on the floor, due to ice melting, the mini-pump starts pumping the water, to drop it into the other part.

The automation for the ice-maker are not used actually. Ice-makers are always working.

The point is : the room temp keeps going up.

For me, there's only 2 heat sources : the 90° water, and the heat produced by machines.

As I'm deleting heat, I still don't get why I cannot reach 0° on my temp sensor. I've brought (debug mode + sandbox, not used in survival yet) some ice at -273° into the conveyor at the beginning to lower my room t° at 0° faster. Then I've stop this input trying to "launch the setup". And slowely but surely, temp sensor is going up. It's 6° now.

Does it mean than the 20% heat i've deleted doesn't ever cover heat generated by machines ?

Is the ice-maker still generating its own heat, indenpendetly of the heat removed from water and partially destroyed ? If yes, is it supposed to be still "heat removal positive" ?

Many thanks for your help !

 

[OxCD]

Hem...  Unlike what I've seen recently, it seems that the ice-maker generate fixed amount of heat : 16kDTU/s (nearly as much as a petroleum generator... woaw).

Wasn't it supposed to be depending on heat removed, as mentionned above ?

[Game Update] - 346893
- Ice Maker now deletes 20% of the heat from water instead of almost all of it.

[qda]

The SHC difference between ice and water, plus the fact that you most probably pump out water that is colder than your room should explain why it can't get any colder : it will probably stabilize somewhere between 5 and 10°C depending on the throughput of your contraption.

[OxCD]

13 minutes ago, qda said:

The SHC difference between ice and water, plus the fact that you most probably pump out water that is colder than your room should explain why it can't get any colder : it will probably stabilize somewhere between 5 and 10°C depending on the throughput of your contraption.

I pump out water colder than my room, I agree, that's why pipes through metal tiles are radiant gold, to balance. And before it reaches the end of this line, it seems that it does as expected... :-/ What do you mean by SHC difference ? (must come from my lack of knowledge into physics).

[qda]

Since water has twice the specific heat of ice, when it melts, you can see this as some form of heat creation. What it means is that since your 10kg water pool contains much more energy than what your ice is capable of absorbing, as long as you have both water and ice in roughly the same quantities in contact, the temperature will necessarily stabilize above the melting point, which is around 5°C. And since you lose a bit cold by pumping out the cold water, that explains your observed 6°C, which will probably rise a little bit more before stabilizing.

The main question is, what use do you have for this room, and what's your expected temperature in it ? If you want it barely below 0°C to maximize your ice creation while maintaining ice makers cold, you can improve your design by not letting any ice melt. I don't have great improvements to propose, but what i would do is the following :

Metal tiles are probably not needed, they are transfering heat way too fast to have precise control of your ice temperature. Instead, I would run the conveyor belt through hydrogen. (edit : on the first travel, from loader to shutoff, if the ice never goes above, let's -5°C, you can certainly keep the metal tiles, if ice temperature rises too much, remove one or two metal tiles, adjust accordingly)

Then, your loop is way too long. If you look at it, your ice goes through 11 tiles from your loader to the shutoff. This length is what dictates the temperature drop. When the ice loops back into the room, it goes through an additional 15 tiles, more than the first travel, giving you a very imprecise control over the output temperature of the ice. I would first move the temp sensor next to the shutoff and slap a diamond tempshift plate behind it. And then, i would make the back loop 2 tiles long (past the shutoff and immediately back in the loop right before the shutoff). That way, your ice will lose a few 0.1°C everytime it loops, giving you a much more precise control of the temperature to avoid the melting while still cooling the room enough.

This is certainly not the most optimal solution but I feel like it should work properly, and without any major change to the room !

Hope you get it working !

[avc15]

Ice maker emits 16 kdtu per second, but it also cools the ice at a fixed rate which works out to around 20 kdtu per second. So you're right on both counts. It's a fixed rate that also works out to a percentage of cooling.

As to why is there a lower bound on temp. When you load hot water into an ice maker some heat will just naturally transfer out. Not a huge amount but some. So there's an equilibrium point.

[OxCD]

Thanks all guys for your answers !

25 minutes ago, qda said:

Since water has twice the specific heat of ice, when it melts, you can see this as some form of heat creation.

Ah I think I'm getting it. Didn't tought about this.

With your suggestion, I would have one worry : if I let my ice going to the other part of the setup without giving it enough time to cool this room, isn't the t° going to rise up again and again, without limit (ice-maker will be used continuously, so much more heat will be brought here) ?  Indeed if I do so I have to shorten my rails or else, for a better control.

[qda]

Since I didn't really know how Ice Maker worked, that was bad advice. Well, not bad per se, but strictly useless.

56 minutes ago, avc15 said:

Ice maker emits 16 kdtu per second, but it also cools the ice at a fixed rate which works out to around 20 kdtu per second. So you're right on both counts. It's a fixed rate that also works out to a percentage of cooling.

If this is right, then in your case, the equilibrium temperature in the room is fixed by the throughput of your system, how much ice it can produce per second, and thus by the input temperature of the water.

16kDTU/s from the ice maker to compensate to keep the room cold means heating 400g/s of ice from -20°C to 0°C

If the ice maker really cools down water by 20kDTU/s, it takes 1100s (almost two cycles...) to cool 50kg of 90°C water to -20°C, that means 45g/s of ice produced. In other words, you would need your input water to be 12.5°C to achieve a 0°C equilibrium.

Well then, an easy move would then be to move the loader, remove the pump and automation, extract the ice immediately, and slap in 3 wheezeworts. You already have a sweeper to fertilize them with phosphorite automatically.

[OxCD]

Bwarf. WW wasn't planned, as the goal was auto-cooling from the ice-maker and avoid any other cooling. It's not a setup "because I need it". I'm trying to optimize this one as much as my knowledge can drive me.

I'm cooling 80° water, and it seems to take only 1 cycle.

Also the water on the floor is wanted (a bit) to spread more efficiently the heat, than in hydrogen.

I'm already thinking about using cold melted water instead of ice... There's some weird aspect I don't get in the thermodynamic here :-/

[qda]

52 minutes ago, OxCD said:

There's some weird aspect I don't get in the thermodynamic here :-/

Well it cools down the water, and generate heat, but a little less than what it cools. This difference between heating and cooling can be expressed in terms of temperature : in a closed system, if you go from 90°C water to -20°C ice and use all that ice to cool the room itself, you will end up with a stable 82°C water and room. From 90°C to 82°C is the difference between the heat generated and removed, the effective cooling done by the ice maker. Now doing this is not really efficient power-wise, time-wise, and defeats the purpose of producing ice. Hence, you either need less than 12.5°C input water to stabilize the room around 0°C, or you will need to add some external cooling if you want a cold room and extracting ice at the same time.

But do you really want the room to be cold ? Because with everything made out of gold, you can certainly stabilize it somewhere between 85 and 90°C while keeping a good ice throughput. The room will not be cold, but will be self-cooled nonetheless.

Also, all of this assuming the ice maker cools down water by 20kDTU/s, which seem fairly low, but the game doesn't mention the cooling rate. If takes around 1 cycle to freeze 80°C, this is almost twice 20kDTU/s, so numbers won't be so tight.

 

 

 

 

[OxCD]

Yup I don't have the numbers for the cooling effect of the ice-maker. But your explanation clarifies a lot anyway ! Yeah I could imagine a room at 85°, that should not be an issue indeed. But it does mean that the ice should not leave the room, otherwise the "heat" will stay, but the "cooling" will move.

The biggest point you've highlighted is the efficiency power-wise and time-wise. I think I'll have to change something into the concept, but I still don't know what.