Hi it seems that the full cycle of centrifuge would give 90-100% pure U235.
This purity isn't use in nuclear reactor (they use 5%). Maybe you should think to add a setting to disable the uranium cell from the pure U235 or make it way more powerful compared to the mix uranium one . From what I find online U235 pure seem to be around 40 time more energy dense than normal reactor grade fuel. So maybe give it a value of 10-20 Gj.
Super mode by the way.

I like the temperature idea .
But maybe it would be nice to tweak it a bit to represent the concentration of u235.
Like natural concentration is 0,7% it could equal to a temp of 70. And reactor grade concentration of 5% would make a temperature of 500. With military grade of 95-100% a temperature of 9500-10000 degree.
Maybe also add a cycle from 70 to 35 and one from 35 to 0 then get U238.
Finally I guess you could make that the more close to 100% the less increases of concentration you get. As it became harder to increase the concentration.

It is unrealistic but for gameplay purposes I thought it'd be more interesting to have the player centrifuge fuels to very high purities.

After some testing I decided to simplify the uranium enrichment from temperatures to 14 separate fluids. Its a bit clunky but makes for better UX since you don't accidentally mix (and ruin) all your uranium stock with one misplaced pipe.
The idea is the pure U-235 cell be much more energy dense than the mixed 235-238 option, so I might buff up its GJs a bit in a coming update.

I see.
If power ratio are kept it should be 20-40 time more energy according to what I gather online. But for gameplay reasons I would say 2-4 time. Or you could play with the fuel cell weight instead. Like make it more power dense without necessary make it more powerful per cell. Or a mix of both.
Like 1 U235 pur for one full cell = 1 mix in energy but 1/5 in weight.

By the way I am trying to make a tweaking mod for your mod . I don't know if I will finish it/ it will work as it will be my first mod.
But for the moment I reversed your change of separat fluid but instead of 2 different liquid output I made the lower concentration solid so no risk of mixing both.

I found the settings layer for it quite interesting. If you finish it up we could merge it into the main mod and give everyone settings :)

Yes no problem.
I posted the mod
https://mods.factorio.com/mod/transplutonic_rebalance
The weight and fuel value settings are working fine (normally).
I am working on tidying the code for the moment.
Do you have specific settings you would like to had to your mod?