Some thoughts on thermodynamics

[Gus Smedstad]

For the most part, Oxygen Not Included treats heat as a waste product. You are always generating it as a side effect of almost anything. Until you get to the late game, you're primarily concerned with not just moving it, but eliminating it. It's not a resource you can use for anything in the early and mid game.

Aquatuners, thermal regulators, and mechanical radiators (grids of radiant pipe) don't eliminate heat. They just move heat from one medium to another.

Wheezeworts and AETNs destroy heat, violating conservation of energy. To date, my focus has been entirely about moving heat from steam, water, and molten metal to where it can be destroyed by these. I.e. cooling a geyser containment building so the low-temperature steam condenses to water where I can use it, and further cooling that water so I can use it for crops.

This feels rather wasteful, it'd be nice if we could use that thermal energy somehow.

In theory, steam turbines would be a way of turning thermal energy into electrical energy. In practice, they're completely out of whack, consuming absolutely enormous amounts of thermal energy for comparatively little electrical energy. The conversion rate's between 300 DTU per joule and 6,000 DTU per joule, depending on how many ports you use. If you're using aquatuners to move energy to the input steam, it takes 1 joule to move 487 DTU from water, or 1 joule to move 984 DTU with supercoolant.

Thus you cannot possibly break even if 3+ ports are open, if you're moving heat from low-temperature sources like most heat sources we worry about. The turbine can only be a net source of energy if you're using a high-temperature liquid or gas and transferring the heat via radiant pipes, which costs no energy.

The practical uses of heat are things I haven't done in the game yet. I'm thinking the steam required for the early steam rockets, or a boiler to heat crude oil up to convert it to petroleum.

The only high-temperature outputs I'm aware of that might be used in a steam turbine without aquatuners are metal volcanoes and the hot petroleum from that crude oil boiler I mentioned. The molten metal one can't use a radiator - the radiator's pretty much guaranteed to cool past the solidification point. You could drip it into the steam input chamber to create superheated steam. I haven't attempted this.

The energy output from the steam turbine won't be high, but the cooling effect is significant. It's 2kg / s * 75k * 4 DTU /g/K = 600k DTU/s per open port, which is 7.5 AETNs or 50 wheezeworts in hydrogen. The tricky part is recovering the steam from the output for re-use, which is 480 watts / port if you're using gas pumps. So you could either go for max energy, 1520 watts plus 600k DTU/s cooling, or max cooling, net loss of 400 watts for 3,000 k DTU/s of cooling.

That's theoretical, I haven't actually tried to build such a beast.

 

[Neotuck]

I wish the forums had a better search function so new members can find old topics

[Gus Smedstad]

I had hope for a more... productive response. I’ve read, for example, threads talking about steam turbines, but none talking about their use with anything but things like volcanoes, and no numerical treatment of the energy or cooling effects.

[Neotuck]

8 minutes ago, Gus Smedstad said:

I had hope for a more... productive response. I’ve read, for example, threads talking about steam turbines, but none talking about their use with anything but things like volcanoes, and no numerical treatment of the energy or cooling effects.

that's the main reason for a better search function

this is an old topic and using volcanoes for steam has been tried for over a year and so far no one has made a productive build without using exploits

The main problem is turbines delete heat faster than volcanoes produce them so they are not reliable  

[KittenIsAGeek]

As @Neotuck mentioned, this topic has been discussed a LOT.  Many of the pages have calculations and example and show how some ideas work and others don't.  Unfortunately, there isn't an easy way to search the forms.

Generally, there are several methods that have been used a lot:

• Counter-current heat exchangers to preheat crude for boiling petrol
• "Oven" type set-ups using doors in vacuum to transfer heat to a cooker or boiler
• Closed (or open) loop piping (gas, liquid, rail) through radiator type layouts

One problem that I've personally run into is that until you get supercoolant, most of the materials available to store and move heat are temperature limited.   It is difficult, for example, to boil oil into petrol using water.  So I generally end up with a number of disconnected systems that all use different materials for dealing with heat. 

Another problem is that heat transfer works best with a high-temperature differential.  Want to boil 10kg/s of water into steam and have it hot enough to run your turbine?  Its going to be very tough to do with the 'waste' heat from your newly-boiled petrol. 

Finally, there's the problem that any work you do with heat results in some of that heat getting deleted which throws off all your calculations.  Running a turbine with steam more than 10c warmer than it needs to be? You're potentially deleting a huge amount of energy.  In fact, I think I wrote a post sometime in October talking about how simply boiling water into steam causes some of that heat to be lost -- I think it was a post about cooling your base by boiling water.

However, if you want to use methods that some others label as 'exploits,' things suddenly get a LOT easier.  For example, I built a turbine that boiled a continual 7kg/s of polluted water into clean water that was output at 10c AND produced power for my base in the process.  I had to trick the turbine into running continually, since the turbine destroys more heat than cooling steam to 10c via aquatuners produced., but you get the general idea.

Most of my bases don't use wheezewarts or AETNs -- my current base is an exception.  I try my best to keep and use heat, but it always ends up so convoluted that I don't feel comfortable writing up a post.  The concept is good -- use "waste" heat to do work -- but implementing it neither easy nor straightforward.