Tempshift plate a building or a cell for conductivity?

[_alphaBeta_]

I was trying to figure out why a tempshift plate made out of aluminum (specific heat 0.506, thermal conductivity 113.889) heats faster than a tempshift plate made out of clay (specific heat 0.511 and thermal conductivity 1.111) when exposed to the exact same gas. See attached simple setup. Going by the game description, the heat transfer should be limited to the lowest thermal conductivity which in this case is the hydrogen. Both plates should therefore heat at the same rate regardless of the fact that the plate is reacting with the eight surrounding tiles. This is obviously not the case.

Then I found this buried on the wiki, and the sentence about the lowest conductivity not applying in all cases got my attention. I see that cell to cell interactions are actually the geometric mean of the thermal conductivity and building to cell is the thermal conductivity of the building multiplied by the thermal conductivity of the tile. I'm getting a bit confused on tiles vs. cells in this context, but let's move on. It goes on to say that most things the player can build are "buildings" with the exception of solid tiles.

Both thermal conductivity interactions above explain why aluminum reacts faster as both do not clamp at the lowest thermal conductivity. I wish the game didn't say anything rather than displaying that it's always the lowest. Ugh. My question is where do tempshift plates fit into this? Are they a building or a tile/cell for purposes of conductivity?

[nakomaru]

There's always exactly one cell medium per tile. In this example it's hydrogen. Tempshifts are 3x3 buildings. Mesh and airflow tiles act as debris.

I think buildings ignore insulation flags and have a (surface area? 20?) multiplier for solid tiles they are inside of. Tempshifts can heat up neutronium. The only other building that touches more space than it consumes is the oil well (4x4 reach, 4x2 consumed).

The same rate of transfer is probably due to the total heat energy of each building being nearly identical (0.91 vs 0.92 J/g/K ・ 160kg ・ T), with the max clamped transfer per tick being (TH1-TH2)/8.

[psusi]

21 hours ago, _alphaBeta_ said:

See attached simple setup. Going by the game description, the heat transfer should be limited to the lowest thermal conductivity which in this case is the hydrogen.

Heat transfer is never limited to the lower of the two element's TC.  Normally it uses a mean of the two.  Insulated and radiant things use only their own TC.

[TheMule]

10 hours ago, psusi said:

  Insulated and radiant things use only their own TC.

Insulated pipes and tiles, yes.

I don't think radiant pipes are special. They use the same log (o geom) mean of TCs. It's just the materials they are made of that have much higher TCs than the ones of regular pipes. One or two orders of magnitude higher. So the resulting mean is quite high too.

[Angpaur]

Radiant pipes are involved in 2 heat transfer types:

Building to Tile: q = k1 * k2 * dT * HC / 10

Normal/Radiant Pipe to Contents: q = kave * dT * 10

Nowhere there is used lower conductivity, however it is possible that, in case pipe to contents, now same geometric average, like in tile to tile heat transfers, is used. Until middle of August 2019 a lower conductivity rule for tile to tile transfers were used. And then suddenly and silently it was changed to be geometric average. It is not mentioned in any patch notes, which is strange.

[psusi]

5 hours ago, Angpaur said:

Building to Tile: q = k1 * k2 * dT * HC / 10

Normal/Radiant Pipe to Contents: q = kave * dT * 10

I'm not sure how the symbols in these equasions map to the TC of the two elements involved.

[Angpaur]

TC is k in those equations.

So k1 is TC of first element, k2 is TC of the second

kave is averaged conductivity of both. Not sure if now it is normal average or geometric.

[psusi]

So you are saying that radiant pipes only transfer heat with their contents faster and exchange heat with the tile they are in slowly?

[Angpaur]

2 minutes ago, psusi said:

So you are saying that radiant pipes only transfer heat with their contents faster and exchange heat with the tile they are in slowly?

I have no idea how you could come to such conclusions looking at the equation of building to tile.

[psusi]

17 minutes ago, Angpaur said:

I have no idea how you could come to such conclusions looking at the equation of building to tile.

Oh, I assumed that was all buildings to tile, not just radiant pipes?  How does it go for normal buildings, for comparison?

[Angpaur]

It is for all buildings and pipes are buildings too.

I don't get why you think that heat transfers are slow if conductivities of two materials are multiplied, in case of that heat transfer type.

EDIT: OK, I can see that it could be slow if one of the materials have TC below 1. The lower that TC then the slower heat transfer. But in case both TC are high then there will be a very fast heat transfer.

But in most cases heat transfer with contents will be faster than transfer with tile, but I wouldn't call it slow.

[psusi]

1 hour ago, Angpaur said:

EDIT: OK, I can see that it could be slow if one of the materials have TC below 1. The lower that TC then the slower heat transfer. But in case both TC are high then there will be a very fast heat transfer.

But in most cases heat transfer with contents will be faster than transfer with tile, but I wouldn't call it slow.

Hrm.. I thought that radiant pipes also got a boost when exchanging heat with the environment, not just the contents.  I could have sworn that regular pipes seem to do a good job matching the temperature of their contents too, then have a decent gradient to their environment where they exchange heat more slowly.  I'll have to take another look.  I wonder if this has changed over the years?

[Angpaur]

Radiant pipes have doubled TC so this makes them more efficient at exchanging heat both with contents and tiles.

I think I need to mention what HC is - it is heat capacity * mass of the hotter material. So when it is higher then heat transfer is faster. This also means that situation depends if pipe is the hotter part in heat transfer or tile. Pipes might have smaller mass than tiles so this will also affects the heat transfer speed. So as you can see there are quite a few variables here, so that is why you can have different experience.