[Vwdiesel] 1980 Rabbit running the treadmill tonight!

Area31 Research Facility stephensrw at stn.net
Sun Apr 17 12:33:29 EDT 2005


I have some hard numbers for fuel consumption that are excellent and
indicate that I am getting what looks like over 30% efficiency in fuel to
electricity production.  At 6.7 kW electrical load I use just 0.3 litres per
kWH (that's about 0.079 US gallons/kWH).  That is two litres per hour at
that load.  At just 3 kW load the efficiency goes in the toilet.  It gives
me just 0.57 L/kWH, drinking 1.7 litres per hour.  I have determoined that
much fuel is consumed just making the engine spin at 1800 RPM with no
electrical load whatsoever and that gives me an idea for a dual operating
mode to handle the light loads when I don't need 6 kW or more.

I think that by lowering the engine speed to 900-1000 RPM and liniting the
electrical load to 3 kW (I'll use a diode bank, charge batteries and run off
an inveter since 60 Hz will no longer be available) I can get near unloaded
idle fuel economy which on the 1.5 VWD is amazing.  Engine heat drops so low
at idle that you could freeze to death sitting on the engine in the winter
here.  My alternator outputs 465 volts 3-phase at 60 Hz at 1800 RPM.  At 900
RPM I get about 230 volts AC at 30 Hz.  I have used that at a slightly
elevated idle throttle setting to run three 1 kW, 230 volt incandescent
lamps and the engine runs fine!  A speed governor is not required in this
mode.  I have to do more experimentation in this area as my electrical
genset control panel is not yet built and this mode of operation could
easily be incorporated into the design.

I am using 100% of the coolant heat and some of the exhaust heat to heat my
shop building.  Too bad I just got this system going in time for summer.

I am looking at purchasing a large single cylinder Changfa diesel in the
15-18 HP range to use to make domestic hot water for the house and to drive
a large DC generator that will charge forklift batteries as will my proposed
wind turbine.  My plan is to run the Changfa near 24/7 at very light load
and slow speed (maybe 900 RPM) hoping to get extremely miserly fuel consumpt
ion and very long engine life.  I posted a question earlier to find someone
out there with Changfa experience and you have fortuitously come foreward.
I'd like to discuss this with you off list or by telephone if you'd like to
send me your phone number privately.
The VW plant operated in the low speed DC charging mode discussed above
would also be available to charge the same battery bank fed by the Changfa
system and the big wind turbine system.

I think I'll try to run a 3kW low speed test of the VW system today for some
fuel numbers.


----- Original Message -----
From: "Val Christian" <val at swamps.roc.ny.us>
To: "Area31 Research Facility" <stephensrw at stn.net>; <vwdiesel at vwfans.com>
Sent: Sunday, April 17, 2005 9:02 AM
Subject: Re: [Vwdiesel] 1980 Rabbit running the treadmill tonight!

>   I'm running about two litres per hour average.
> Rob,
> I have a couple of one cyl chinese built diesel generators.  I've done
> load testing with them.  The most relevant point is that I can run a load
> between 3.5 and 4 kW, for 14 hours on 3.3 USgal.  That works out to just
> under one USquart per hour.  I figure it's about 8 oz of fuel per kWhr.
> These calculations are all approximate, but they're in the ballpark of
> 35-40% efficiency.  I doubt the total system is actually running there,
> but the estimates show it to be close.  You're not going to get 80%
> efficiency, and if you get 20%, you're probably too low, and something
> is wrong.
> At local diesel "pump" prices, that is about $0.16 US per kWhr, or almost
> twice the marginal grid rate.  Not bad, and obviously alternative fuels
> will drive down the price.
> Also, my generators are a little over 10hp, and I don't recall the hp
> you said your will produce, but I figure it's 12-18 range.  Inductive
> amp meters are relatively cheap, in the clamp-on embodiment.  Friends
> have urged me to install torriods on my power lines, and adapt meters
> to them, so that I can have continuous current monitoring.  Since I
> have two clamp-ons, I'm not in a hurry.  I do have a $5 DVM, with a
> freq meter setting, and I've monitored frequency output with that.
> I am told, but have not verified that compressors, like in a refrigertor
> can be very frequency sensitive, and 2 or 3 hertz difference can cause
> reduced output and increased heat.  I haven't tried to verify the theory
> nor measure the results.
> A really nice thing about your powerplant, is that at 1800 RPM, the
> VW diesel should last a very very long time.
> What are you doing with the waste heat from the engine?
> Val

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