ALAN/ALAN D wrote: ↑Wed Dec 28, 2022 11:10 am
Ref “A bit of a non problem for the occasional power cut but easy enough to extend the exhaust into a coil and then vent it. “
With Diesel If you extract to much heat from the coil Sulfuric acid will condense in the coil. The temperature at the end must be above 138 Deg C.
For the occasional power cut I would stick with normal Diesel generator
I have converted petrol cars / lawn mowers / generators to propane. First car in 1970
Propane a lot more reliable than petrol. Leave it for years. Then go and start it.
I guess it would be sulfurous acid from the oxidation of hydrogen sulfide. The welder chap that used to do my repairs was often required to plate the silencers of large SI converted diesels at a landfill gas site near Redhill and I had some flue gas recirculating pipes perforate on a woodchip burner at a large store, being used to dispose of flat pack returns, so I recognise the problem of acid condensate even on stainless steel.
I am surprised at the 138C figure as while I know at lower power levels diesel exhaust is cooler than SI exhaust but I would have expected the water vapour partial pressure to stay gaseous in the mixture with CO2, O2 and N2. After all even with methane burning in low excess air in a boiler the flue temperature has to drop below 50C to reach the dew point and go into condensing mode. Wood burners are a bit different as they must exhaust above 100C to prevent any condensation and associated stains.
A couple of potentially contradictory points:
I would go for natural gas or lpg in a SI genset simply for their cleanliness and extended oil change intervals, I too had a V8 LR converted. One of the things I note with the small stationary engine lpg conversions is they don't sense for a spark and cut the gas supply when it disappears. SI engines work at stoichiometric fuel to air mix and their exhaust temperature is constant.
A diesel beats an SI engine for conversion efficiency at lower power settings but if you aim to only charge the battery at bulk charging rate plus any base load then the engine can be set to run constantly at a fixed, optimum load when there is little difference with a naturally aspirated diesel. Once reaching a float voltage the engine is off, thus it does not put many hours on the engine compared with running a synchronous genset all the time, BTDTGTTS.
So hotter exhaust and water cooled makes me favour SI for regular use for low hours.
I have nothing against diesels having spent my working life sitting on various diesel plant, though I doubt they did my lungs much good.