turbo powered pmg ?

[knighty]

they engine was made in July 1959 (according to the serial number on the fuel pump)

as paul said, I'll be running it on animal fat (aka lard - a bit like frotters engine)
(we produce about 3 ton a week, so there's no shortage!)

turbos only force more air into the engine - if you want more power you have to add more fuel too


the engine is 200bhp at 1800rpm... hopefully I can run at a much lower rpm and still get enough power out of it... the lower rpm should greatly increase the efficiency of the engine.... and it's bit tall cylinders/pistons should be perfect for low speed running on lard


I was thinking about how to set up the rpm/power output of the engine today... and I had a good idea (I think)

I'll monitor the exhaust temperature of the engine and use that to work out how hard I'm working the engine (at any given rpm)

that way I *should* be able to run it somewhere near the sweet spot of 80% load... where's it's most efficient and where it's working hard enough to be nice and hot to so the lard burns well :-)

[camillitech]

I was thinking about how to set up the rpm/power output of the engine today... and I had a good idea (I think)

I'll monitor the exhaust temperature of the engine and use that to work out how hard I'm working the engine (at any given rpm)

that way I *should* be able to run it somewhere near the sweet spot of 80% load... where's it's most efficient and where it's working hard enough to be nice and hot to so the lard burns well :-)

Excellent idea Knighty, I swear by them, there's a link here to one I fitted to the 'Old Girl' a couple of years ago http://lifeattheendoftheroad.wordpress.com/2009/09/30/i-will-do-it-tomorrow/ it's off an aircraft but was quite cheap and if you want one for lower EGT then get the twin engine version.

Good luck, Paul

[EccentricAnomaly]

Apart from detecting problems, as Paul mentions, the main use of EGTs in piston engined aeroplanes (at least the bulk of general aviation aeroplanes with 1930s designe Lycoming and Continental engines) is for fuel economy in the cruise. For take-off, landing and general mucking around you fly with the mixture in the fully-rich setting (which is actually slightly over rich; some unburned fuel is spat out for cooling). When you're settled down in the cruise you then lean the mixture a bit. On aircraft without EGTs (most of the ones I've flown) you reduce the mixture progressively until the RPM drops then richen it up a bit. With an EGT you adjust the mixture to get peak temperature.

I hope that's all right; it's a while since I've flown and I didn't do a lot of cruising flight when I did. Still, I expect old slow-reving low-power-density generators are pretty comparable to run-of-the-mill light aeroplane engines. The main differences are that these aero engines are air cooled (flat H configuration like an old VW engine with detachable cylinders and pots) and have dual magneto-driven electrics. Oh, and the aero engines are eye-wateringly expensive and only last about 2000 hours.

[knighty]

camillitech, thanks for the vote of confidence and the link - I'll buy the twin engine one as soon as I start getting the engine setup

I was a bit worried about how I was going to set up the rpm/power settings.... up until now I thought I was going to have to set the rpm of the engine, and then load it up till it belched black smoke (and then ease off a bit)


EccentricAnomaly.... I'm going to lock that info away.... and every time someone looks at the generator* I'll pop it into the conversation and look really smart! :-)



(*with all the work I'm going to put into it.... I'll have to show it off a bit :-))

[Ivan]

If you're aiming to get high efficiency in terms of electric+heat, then consider not running at high load. There are apparently good reasons for running at high load (hot = more complete combustion), but if you run at low load, the exhaust gas speed and temperature will be lower. You have more time to remove a smaller amount of heat therefore you'll achieve much better heat-extraction efficiency.

[knighty]

good point ivan.... any idea what kind of load i should run at ?  (how long is a piece of string?)



I think the only way to really figure it out will be to run at a set load at different rpm for a day at a time and watch the fuel consumption... and try to figure out how much hot water I'm making (the tricky bit)

[camillitech]

You really do not want to go below 50% load Knighty and 75% would be better or you will have issues with 'bore glazing', something that is a problem on marine gensets. The generator has to be large enough to supply lots of loads in an emergency but for 99% of the time is only running lights etc. We had big problems with this until resistive heaters were added a few years ago to 'load em up'.

I have heard of people removing it by running the engine flat out with the air filter off then tipping Vim or Ajax down the inlet manifold  Never tried it myself though, I prefer to just keep them working hard.

Good luck, Paul

[Ivan]

Yes, it's a toss-up between efficiency and engine life. As long as your heat exchanger is good enough to remove the bulk of the heat, it does not matter what load you're running, but making something 95% efficient at scrubbing heat, when you're producing exhaust gases a lot faster is quite tricky.