Liquid pipe radiator comparison

[Carnis]

Been wanting to run a methane based oxygen liquefier, as it would be about 2.2x more efficient than a hydrogen radiator, for making liquid oxygen via the use of an aquatuner and the rather high heat capacity of methane/natural gas. Methane would of course never liquefy oxygen, but you could theoretically get oxygen as low as -181, which would be easy to finish off with a 2nd stage hydrogen radiator. Hydrogen radiators on the other hand work ridiculously efficient because of gas-solid-gas heat interaction having a 25x multiplier.

Unfortunately liquids do not have this 25x multiplier.. So went and tested each liquid pipe and their potential as a radiator, which would be the simplest and cheapest way of cooling polluted oxygen. This was the test setup:

 

We ran methane down from -181 degrees as low as -162 degrees, then built a pipe bridge and vented the radiatorloop. Each loop had 14+14 pipe segments and 2 abyssalite bridges running inside polluted oxygen at 273K / 0 Celsius. We had 45 kilograms of polluted oxygen to cool.

 

First off, pipe based methane radiators are not viable in the current build. The heat simple does not leave the liquid in any reliable time frame. Took around 5-6 cycles to get methane down to -162 Celsius inside the tungsten pipe, which paradoxically removed heat from the liquid slowest..

 

Results were a bit confusing:

 Pipe temp pO2 temp Methane temp pipe conductivity pipe capacity
Abyssalite pipe             −0,1          −0,1               −181               0,00001                    4
Igneous pipe           −19,6        −18,9               −162                          2                    1
Granite pipe           −24,2        −23,5               −162                     3,39               0,79
Sandstone pipe           −24,5        −23,7               −162                       2,9                 0,8
Obsidian pipe           −72,7           −72               −162                          2                 0,2
Sedimentary pipe              −72        −71,2               −162                          2                 0,2
Wolframite pipe           −89,5        −89,1               −162                        15             0,134
Tungsten pipe           −94,5        −93,9               −162                        60             0,134

 

None of the liquid pipes were viable for cooling gas with any realistic timescale with a radiator.

Granite, with the highest heat conductivity of the stone pipes, was only slightly better than igneous pipes.

Sedimentary pipes / obsidian pipes conducted 72K heat transfer to the 45 kg of pO2 for 19 degrees warmed methane. Beating granite by 50 degrees!

 

The other pipes cooled gas according to the pipes specific heat capacity and this explains superior results of obsidian/sedimentary. You should use obsidian/sedimentary in cooling base segments with liquid (polluted water).

 

Wolframite and tungsten have equal specific heat capacity of 0.134.

Tungsten took longest to cool, but cooled the pO2 most down to -95 degrees, even more than wolframite, which has the same pipe heat capacity. I cannot explain this difference..

 

I spent a few hours building another methane system, but will write about it in another post.