[Vwdiesel] 1980 Rabbit running the treadmill tonight!

Area31 Research Facility stephensrw at stn.net
Mon Apr 18 00:20:46 EDT 2005


I did not re-mention in this post that at a decent load of 6.7 kW my diesel
was doing this at a rate of just 0.30 litres/kWh. In this area the engine
clearly has just enough load to be clearly 'in the zone'. Cogen heat output
is significant also at this load to be very helpful heating the large 3500
sq.ft. building on cold winter days. 0.3 litres/kWh is almost 200% better
than the low load regular speed 0.57, and low load reduced speed 0.60,
consumption numbers.  Consider also that the winter diesel I used to obtain
these results has less energy per gallon than the summer diesel  you used in
your example.  That is a darned good efficiency I'd say for a small plant.
Now if I could only get 0.3 litres/kWh at 1-3 kW instead of 6-7 kW I'll be
able to afford to run the beast (whichever one this is) in my off-grid plan.

At least now I've got standby power for blackouts covered and running and
heating my shop more economically in winter.  If you've ever heard a
ka-ching. ka-ching, ka-ching sound way off in the distance, that is my
inneffcient single to 3-phase rotary converter in use on the grid while I
work in my machine shop.

Let's see, the electricity used to machine and weld my big wind turbine may
be generated with recovered waste oil. ;)  Now THAT is recycling!


----- 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 10:56 PM
Subject: Re: [Vwdiesel] 1980 Rabbit running the treadmill tonight!

> > I did some 'speriments today with my VW 1.5D running at 1200 RPM.  I was
> > able to make 1.5 kW electrical load at this speed with winter diesel as
> > using 0.9 litres/hour.  That means the engine will run doing this power
> > delivery for 4.2 hours on a US gallon.  There was not much heat
> > but the engine coolant did stabilize at about 185 F, the thermostat
temp, so
> > there was enough heat to keep the engine happy.  The engine sounded very
> > quiet and relaxed like it could do this for years.  The efficiency was
> > to the same as running at 1800 RPM and 3 kW load with a throttle
> > I  measured  0.57 litres/kWh doing that and today at 1200 RPM slow speed
> > 1.5kW load got 0.60 litres/kWh.
> The fuel burn you mention here is nearly identical to what I get
> with a 3.5 to 4.0 kW/hr load on my slightly more than 10 hp
> air cooled diesel.  The system rated capacity is 6.5 kW, and
> I've been able to get 7.5 kW peak out of it.
> A rough  ball park on efficiency is something like this:
> 1 USgal #2 summer fuel 140,000 BTU
> BTU * 0.293 = watts
> so one gal is about 41 kW/hr
> I realize that there are many design decisions and trades,
> but in general, a powerplant which runs at 75% plus or minus,
> will end up being most efficient.  50% probably works OK, and
> nearly 100% is probably OK.  And it's understood that the power
> output rating can be traded against engine life.
> Val

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