While researching the NERV engine I considered the possibility of LH2 as a coolant for reactors or large nuclear engines such as the LV-NGL 'Deliverance'.
This is how I imagine it would work:
The 'LH2 Boiler' would consume LH2 at a speed relative to the total amount of heat stored in craft, the LH2 would be converted into 'Boiled Hydrogen'.
'Boiled Hydrogen' would then have to be "burned" by a 'LH2 Boiler Exhaust', the 'LH2 Boiler Exhaust' will product thrust based on the rate 'Boiled Hydrogen' is generated.

This is more deep complexity that this mod doesn't really want to deal with