Counterflow Heat Exchange

[Tonyroid]

I found this excellent closed thread from February.  I've been messing with heat exchange like serious business for about a week and you guys had some ideas I hadn't thought of.

I want to share some of my ideas and hopefully spark some new discussion. Nothing would make my day more than a really great heat exchange for large volumes of gasses that aren't in a pipe (which tends to require a really big device because of SGs low conductivity).

I'll put my ideas in additional posts.

[Nightinggale]

I haven't tested it yet, but I have been wondering about copper radiant pipes inside copper metal tiles. There should be a 20 thermal conductivity multiplier for placing the pipe inside a tile meaning the radiant heat pipe and the tile should have more or less the same temperature at all time. On top of that metal tiles have nearly the same temperature as nearby metal tiles due to high thermal conductivity. Copper is used because of the high thermal conductivity. This should (at least in theory) allow very space efficient heat exchangers.

[Tonyroid]

You've probably seen something like this before. But what you (maybe) don't know is that 1kg/s of liquid in a pipe can be heated/cooled to any temperature without breaking the pipe. (A guy on reddit showed me).

I have a LOT to say about this thing. It's very heat-efficient but the dynamics with pressure and specific heat make it tricky when you try to scale it up for large volumes.

29 minutes ago, Nightinggale said:

I haven't tested it yet, but I have been wondering about copper radiant pipes inside copper metal tiles. There should be a 20 thermal conductivity multiplier for placing the pipe inside a tile meaning the radiant heat pipe and the tile should have more or less the same temperature at all time. On top of that metal tiles have nearly the same temperature as nearby metal tiles due to high thermal conductivity. Copper is used because of the high thermal conductivity. This should (at least in theory) allow very space efficient heat exchangers.

I've tested that. It's the best heat exchanger I know in some ways but it has weaknesses too. It can fit in a small space if you arrange it in a checkerboard pattern and it exchanges just wonderfully. But the stuff has to be in pipes, which means it's not great for high volume or anything you don't want to spend the power to pump. It uses an intermediate medium (metal tile) for the heat exchange, which means that in theory it can't be the best solution, but doing better seems to involve large/complicated stuff. By the way, for that fabulous efficiency you have to use valves to balance the specific heat of the stuff you are exchanging, or else one will overpower the other (although, sometimes that might be what you want).

Oh, also, I did this in a vacuum so I didn't have to put in insulation. around/in it.

[Angpaur]

26 minutes ago, Tonyroid said:

You've probably seen something like this before. But what you (maybe) don't know is that 1kg/s of liquid in a pipe can be heated/cooled to any temperature without breaking the pipe. (A guy on reddit showed me).

So what you wanted to show us is an old know exploit?

This is a let down. I hoped for some interesting and insightful stuff

[Tonyroid]

22 minutes ago, Angpaur said:

So what you wanted to show us is an old know exploit?

This is a let down. I hoped for some interesting and insightful stuff

Hmm. That seems exploity to you? It doesn't seem to me like the kind of thing that would be an accident. Don't worry, I have LOTS of other stuff to contribute that doesn't depend on that. Besides, this forum is about sharing. Half of people have never built a rocket and they can benefit from learning this stuff.

[Nightinggale]

3 minutes ago, Tonyroid said:

That seems exploity to you?

I think it's the part about 1 kg/s crude oil not breaking the pipes. Apparently Klei has mentioned it as "Won't fix. It's part of the game design that one gram can't break pipes". If that's the case, then I won't see it as an exploit.

One thing you can do to improve the first design is to instead of having a row of metal tiles, have two rows and a door in between. Add a thermo sensor, which opens the door if the temperature is higher than X. This way you can keep the lower metal tiles on the temperature, which is just hot enough to make sour gas, but too cold to heat the sour gas. This would make the system more efficient because the sour gas would need less cooling.

The tile thermo sensor from Sensory Overload would be ideal for this because it's a metal tile, which has a thermo sensor triggering on the temperature of the tile rather than the gas next to the tile. A vanilla thermo sensor in the sour gas would work too, but it's harder to get a stable temperature right at the boiling temperature.

[Tonyroid]

Oh, also, cheap Iron metal tiles seem to work just about as well as thermium. But good conductive pipes make a significant difference.

25 minutes ago, Nightinggale said:

I think it's the part about 1 kg/s crude oil not breaking the pipes. Apparently Klei has mentioned it as "Won't fix. It's part of the game design that one gram can't break pipes". If that's the case, then I won't see it as an exploit.

One thing you can do to improve the first design is to instead of having a row of metal tiles, have two rows and a door in between. Add a thermo sensor, which opens the door if the temperature is higher than X. This way you can keep the lower metal tiles on the temperature, which is just hot enough to make sour gas, but too cold to heat the sour gas. This would make the system more efficient because the sour gas would need less cooling.

The tile thermo sensor from Sensory Overload would be ideal for this because it's a metal tile, which has a thermo sensor triggering on the temperature of the tile rather than the gas next to the tile. A vanilla thermo sensor in the sour gas would work too, but it's harder to get a stable temperature right at the boiling temperature.

You are right about the door. I'm working without it in one of my projects and I totally forgot to put it in.

I've seen a hydro sensor used to operate the door and it was the best one I tested. It detects when petroleum is present and closes the door.

[Tonyroid]

This is weirdly specific but it makes such a big difference that I want to share it.

There's this problem with NG cookers that makes them hard to get working efficiently. Basically, the specific heat of the oil/petroleum isn't high enough to "push" the heat back that comes from the sour gas (because sour gas has a higher specific heat). So no matter how hard you try, eventually the heat always backs up to the condenser and saps the cold out in a total waste. A steam turbine to eat heat helps but doesn't fix the problem. (125 degrees competing with your condenser is better than 540, but it's still there.) The only way they usually work is if you eject heat in the natural gas.

I found a way to prevent that. This example is a lousy cooker but it's just to illustrate the concept. Look at the loop of oil on top. The idea is to enter the heat exchange at the same place where the main oil line enters, run through the cold part and into the hot part. Exit the heat exchange at the point where the oil in the loop gets back to the same temperature it started at. That way, when it loops back to the beginning, the oil is the correct temperature to start over again.

The extra oil increases the specific heat moving through the heat exchange. That lets you more effectively recover the coldness out of the NG to chill the sour gas and carry the heat from the sour gas back toward the hot end of the heat exchange.

I know that was long and annoying, but if you nerd out about these things like me then it's worth it.

[fiziologus]

Rediscover heat recuperation. This work. Even IRL. But need good temperature control.