> My understanding of diesel ignition is somewhat informed by WWII-era triple-expansion steamships, which burned bunker fuel, that requiring a lot of heating (u

> My understanding of diesel ignition is somewhat informed by WWII-era triple-expansion steamships, which burned bunker fuel, that requiring a lot of heating (utilising spent steam) just to get it flowing toward the boiler, then again getting toasted immediately before going into the burners. External combustion, obviously, but the challenge of getting a very nonvolatile fuel to burn left an impression. That engine room visit left an impression as well.... Yes, bunker fuel is very much non-volatile stuff. As an aside, they did eventually figure out that you could run slow-running big diesel engines on that stuff too. Perhaps you've seen pictures of such massive engines big as houses, if not e.g. https://www.youtube.com/watch?v=K30_jf-aA_U https://www.youtube.com/watch?v=K30_jf-aA_U These big diesels have some things in common with the old triple-expansion steam engines, e.g. they are directly connected to the propshaft (and thus they turn slowly, about 100 rpm max or thereabouts), and the engines themselves are reversible, so there's no need for any reduction gearing or gearboxes. Similarly to steam ships, they need steam lines in the fuel tanks to heat the fuel so it can be pumped, and then further heated to 130C or thereabouts in order to be injected. So they need a small auxiliary steam boiler just for producing the steam to heat the fuel; modern ships often have an 'exhaust heat recovery boiler', which as the name implies utilizes the hot exhaust from the main engine to produce the steam, so that the auxiliary boiler isn't needed when the main engine is running.