thinking of exploring another option

[mobile_bob]

i didn't really think we would be breaking any new ground with the use of a 4 cyl engine with natgas or propane

what i did wonder though was whether we could effectively use one for cogen operation, and i think we can
economically as well.

having said that, it appears that the unit can be made to run very close to the same kw/hr per btu of fuel consumed
based on the guardian units numbers, and likely those numbers would be improved if the engine they used was significantly
higher comp ratio than their 8.5:1

it would seem that there equivalent to 9kw/hr/gal (adjusted for diesel comparison) could be improved to around 10kw/hr/gal
if the comp ratio was increased to 10:1 or greater.

the problem lies with being able to use the available power afforded by the 4cylinder in order to get to max efficiency, and i don't see
that happening for the average small home for continuous operation, however

i can see the possibility of very good overall efficiency if there is some level of automation/control where the unit is tightly controlled
so that the available power and heat is used effectively and matched to the loads which would require scheduling along with likely
either a grid tie scheme or battery/inverter system.

it might work something like this

the house is cold, there is need for hot water, and also a load of laundry to wash and dry, so the unit is started and all electrical loads are switched over to the cogen. it powers all electrical loads and pumps the harvested heat into the thermal mass of the floor or other storage medium and whatever extra capacity is used to offset the utility power that is used to power the lighter loads while the cogen is shut down or the extra power is used to drive an alternator(s) to recharge a battery bank which in turn would power the lighter loads during cogen off time.

this would allow the cogen to operate on an intermittent basis, and allow it to run at peak efficiency.  with sufficient thermal storage
and good scheduling the unit ought not have to start more than a couple times or at most maybe 4 times a day during cold weather.

even at a half dozen starts per day, the quality starter ought to last at least a couple years before needing replacement.

the one fly in the ointment is the unit likely could not be used efficiently in warmer months where there would be no use for the amount of heat available, unless some develops an absorption chiller/cooling system to air condition/cool the house, then possibly it would math out.

otherwise a much smaller unit sized for summer loads would be a better match, something like a geo metro motor (750cc 3cyl)
or maybe one of the kohler water cooled twins might be a better match?

as for aircooled engine's, why not give one a whirl

if it is mounted in an enclosure and a refer compressor is used, the aircooled heat can be harvested, transported and used cleanly and safely into a living space, via a heat pump scheme.

bob g

[Lloyd]

Hey Bob,

Take a look at this site...it provides only snippet info...but they provide a lot of snippets on many issues.

Lloyd


http://www.brighthub.com/engineering/marine/articles/75641.aspx

In this article we discuss dual combustion engines and the advantages of propane injection in diesel engines.
Introduction

All marine diesel engines in operation worldwide are slowly changing into dual combustion engines (DFDE, or Dual Fuel Diesel Engines) that operate on natural gas and marine diesel heavy fuel oil. The dual combustion engines are gaining more importance due to their efficient performance and proven reliability when compared to diesel engines, which are highly prone to pollution.

Natural gas ignition engines provide ultra-clean combustion, thereby reducing the pollution that will obviously reduce health hazards. Most of the natural gas engines are operated both on natural gas or gasoline and these engines based on the Otto cycle are spark ignited.

All diesel engines in LNG and LPG carriers are slowly changed over to dual fuel diesel engines because of the advantages of the gaseous fuel resulting from the vaporized liquefied natural gases in tanks during sailing.

This gaseous fuel is nothing but the propane-based gases vaporized from the liquefied natural gas. Dual combustion engines are able to consume this gas and convert into useful energy in cylinders. Normally during sailing the gas involved is completely used in these engines and the same engines use diesel as fuel during maneuverings in port.

[mobile_bob]

Lloyd

thanks for the link, i spent a few hours late friday night reading up on the lastest in dual fuel diesel operation
and it would appear there is ample evidence that natgas can be used as the other fuel in an otherwise unaltered
diesel engine.

i found a few references to there being no need to reduce the compression ratio once thought as necessary for operation

that was encouraging and supports the use of our diesels with natgas in dual fuel mode.

my shift to spark engine thinking is based on the increasing difficulty in getting small diesel engines because of the epa
while i have enough to keep me going for the rest of my life i fully recognize our hobby if you wanna call it that will at some point
expire due to the lack of sufficient supply of compliant engine's that are within the budget of a diy'er..

obviously there will always be engine's that are compliant to use if you have enough money, but there is a finite source of older engine's even if you scour up all that are sitting in barns in other countries and ship them,,, at some point the replacement parts will become an issue as well.

take the witte engine for example, here is a wonderful old piece of history and solid engineering, but they are few and far between
and parts are getting difficult if not impossible to come up with.  at some point the listers will be the same i fear, the chinese engine's are already a problem to not only get, but to get parts for as well.

as for dual fuel diesel, i will be keeping my trigen and it will likely be dual fueled with nat gas now that it appears that i will have access to that fuel source.

thanks
bob g

[wiebe]

The germans are in with bob in this .
http://www.vaillant.de/Produkte/Kraft-Waerme-Kopplung/Blockheizkraftwerke/produkt_vaillant/ecoPOWER_Blockheizkraftwerk.html
Its in german ,a translater can translate it ,got a 1kw honda micro unit and some bigger ones 3to 4,7kw .

But its a crappy site .

[Carlb]

Here is a link to my listeroid running in dual fuel mode. the governor will control the amount of diesel to the engine the natural gas is set using a needle valve. While this is not ideal, under a 2k load the ratio is about 80% natural gas and 20% diesel.  If the load increases the ratio of diesel to nat gas increases as the governor pulls the rack open some more. If you have a constant load on your engine, it is real easy to fine tune the adjustments.  The gas solenoid is powered from the gen head so if their is any failure in the engine or generator the gas is shut off.

http://www.youtube.com/watch?v=AwPPui8Fyi0

[Henry W]

One question I have is would direct injection be better for dual fuel mode or it does not matter.

Henry

[sailawayrb]

Here is a link to my listeroid running in dual fuel mode. the governor will control the amount of diesel to the engine the natural gas is set using a needle valve. While this is not ideal, under a 2k load the ratio is about 80% natural gas and 20% diesel.  If the load increases the ratio of diesel to nat gas increases as the governor pulls the rack open some more. If you have a constant load on your engine, it is real easy to fine tune the adjustments.  The gas solenoid is powered from the gen head so if their is any failure in the engine or generator the gas is shut off.

http://www.youtube.com/watch?v=AwPPui8Fyi0

Very cool and similar to the experience I had running propane/SVO several years ago.  I got to about 85% propane under a 4.5K load.  Documented here in the "Diesel/SVO/Propane Control System" photos/descriptions:

http://listerenginegallery.com/main.php?g2_itemId=351

Bob B.

[mobile_bob]

BobB

is that 4.5k mechanical output, or 4.5 kw electrical output

and iirc you are running a 6/1 at 650rpm?

trying to get my head around a bunch of reports from various sources supporting the theory
that even though the engine is ingesting fuel of a lower btu value it is still able to make as much or more power
which can only be explained by a more efficient, more complete or an altered burn rate that the engine is better able
to convert to useful output mechanical work.

an earlier discussion centered around a university of wisconsin project where they dual fueled a CAT engine with gasoline
via a low pressure port injection scheme taken from the gas engine automotive application common to cars. in their report
the demonstrated an efficiency increase to something over 52 or 54% from the oem engine running on diesel alone of 41% efficiency

this is something that fascinates the crap out of me, and something i want to fully explore, test and understand.

just finding papers supporting that it is not necessary or even desirable to reduce the comp ratio on a diesel engine to run it in
dual fuel mode supports earlier crude testing i did on the s195 over 5 years ago now, it too inhales propane quite happily without any signs of detonation or preignition and it has a 20:1 comp ratio.

it even ingested rubbing alcohol without complaint at that time, more recently i tried gasoline via the drop method and it too presented no signs of roughness or knock which would indicate detonation problems.

definitely not enough time to do all i want to do.

the upside is a dual fueled diesel that is used for combined heat and power, using output based emission standards would have no problem meeting the most stringent epa regulations, likely without any particulate filter, no urea injection and maybe not even a cat.

probably be a better neighbor too, in that it wouldn't smell like a diesel

bob g

[TimSR2]

With the recent collapse of natural gas costs due to the shale gas plays in the USA,  a spark ignition  genset makes perfect sense.

  I have been driving propane fuelled trucks on and off since  1982.   I have driven  + 250,000 miles on propane.  My motorhome is on propane.  (single fuel)  With the compression upped from 7.8 to 9.5/1  and the ignition recurved, and a few other minor mods it makes far more power than it ever did on gasoline. I completely shame diesel pushers with my 350 chevy spark ignition propane engine. It's an 82, on propane since 1987.  I had the heads off at 90,000 miles and the short block was still like new. I had to re/re the intake manifold last month and it still  looks like a compresor inside,  Ultra super clean inside  at 169000 km on the block, 28 years old, and 8500 pounds down the road, with 4.11 gears, no overdrive. Comp is 180 on all 8 cylinders.  Gaseous fuels are the ultimate spark engine fuels!

Propane is c3h8,  natural gas is primarily methane, c2h5. So for automotive use the NG is less desirable as it has much less BTU output, and liquefies at high pressure. But for a stationary set it makes perfect sense, especially if it is cheap. And it will be cheap for many years, as the shale gas plays are ramping up big time,and  the Alaska and NWT gas pipelines will be very soon constructed. Experts expect the north american ng market to be depressed for decades.  And conversion from methane to propane  is pretty easy, if you need backup due to being in an earthquake zone

I'd recommend a post smog , all iron inline engine like  a Chev 2.5  or a Ford 300/6 . Or an old Datsun 1000/ 1200 for the smaller sets. Or a Yugo 1300 (lol)  Make sure you have good hard valve seats on these applications. Engines made for leaded gasoline will clap out their valves pretty quickly on gas.

[sailawayrb]

Bob G.

That's 4.5K electrical from ST5 driven by 6/1 at 650 RPM...three 1500W portable heaters and confirmed on the transfer switch watt meter.  Frankly, I never made logical sense of it, but Quinn at the time seemed to explain it as resulting from more complete combustion that allowed for greater BTU extraction than one might expect by say averaging the propane and SVO BTU values.  I think he may have even posted the combustion equation at the time...likely on George's site.  I'm afraid that chemistry was not my best subject, so this is well beyond my capability to attempt to explain properly.    

I can say that the propane demand regulator I use is designed for much more than 6 HP, so it is not flow rate limited when under high load.  Same story for my CO2 regulator that is used for emergency shutdown.  As you know I tend to push design limits by radical designs and over-designing...  If I recall correctly, I think I got my propane regulator from this place:

http://www.propane-generators.com/a-c_kits.htm

Anyhow, the only limitation I encountered during this experiment was the minimum amount of SVO required to maintain good ignition and my fear of exceeding the ST5 5KW rating.  The 6/1 didn't seem to mind this experiment at all and it actually sounded like it enjoyed it.  In fact, the 6/1 always seems to run smoother/quieter even when just running my normal 10% propane fumigation level used for carbon removal.

Bob B.

PS - The primary reason I run SVO and propane is so my suburban neighbors can't detect my operation.  And this was my primary motivation for going with a resilent mount design too.

[BioHazard]

the one fly in the ointment is the unit likely could not be used efficiently in warmer months where there would be no use for the amount of heat available, unless some develops an absorption chiller/cooling system to air condition/cool the house, then possibly it would math out.

otherwise a much smaller unit sized for summer loads would be a better match, something like a geo metro motor (750cc 3cyl)
or maybe one of the kohler water cooled twins might be a better match?

This is the brick wall I always hit. We don't need a lot of heat here. One option might be to build a 4 cylinder generator for winter months and maybe a 2 cylinder for summer use. That way you always have a spare when one is out for service. Has anyone tried to use engine heat directly in a clothes dryer? If I had to guess I'd say that burns the most electricity in my house. I also have a hillbilly 5000gal above ground pool that needs heating every month except august...(don't use it in the winter)

I am hoping to build a "micro" cogen system much like the 1kw Honda unit for my house...I'll need something much bigger for my new shop though, and I want to power all sorts of shop tools with it too, like an air compressor or welder.

Another interesting use I've been considering is a greenhouse to grow food crops, which would need lights and heat in my climate much of the year for part of the day. The key here is that CO2 is fertilizer to plants, and running clean natural gas exhaust into the greenhouse can increase production by up to 30% while heating at the same time.

[mobile_bob]

there sure seems to me that there has to be some alteration of the burn rate with the dual fuel operation
vs standard diesel operation.

diesel fuel is injected, then there follows a delay period, after which ignition occurs marked by a sharp pressure rise
(that diesel knock we are familiar with) it stands to reason that perhaps this sharp pressure can only affect the crank over
a relatively narrow crank angle, whereas

with the propane dual fuel, perhaps the pressure rise is not as sharp, but rather spread out over many more degrees of crank
angle, allowing the engine to make more effective use of the combustion event, converting it into useful torque?

there has to be something to this phenomena, it can't simply be explained by the use of additional propane to make up for
the loss of the fuels btu content, because the engine is naturally aspirated there is only so much air available to burn additional
fuel.

typically we see 6/1 pulling 3kwe relatively cleanly, over that they begin to smoke indicating that there is too much fuel for the available air.  the same engine pulling 4.5kwatt relatively cleanly is a 50% increase in output power, in order to account for that
simply by virtue of added propane to make up for the offset in btu's does not seem at all possible. the propane also displaces air
in the cylinder, so adding more propane can't make more power on its own merit, or so it would seem.

what would be interesting would be to run a test and get the amount of both diesel in gr/kwatt/hr and also lbs/kwatt/hr of the propane used. from that the story could be told.

my thinking is perhaps there is truly an alteration of the burn rate that allows the engine to harvest more useful power over a longer
crank angle than otherwise happens in straight diesel operation, and if there proves to be no offset or increase in propane to make up the lost btu's, the only conclusion left is the engine is demonstrably more efficient in duel fuel mode.

if this proves to be the case, this is where we need to be heading as a group. we end up with more efficient and cleaner engine's and perhaps the epa might look more favorably at these engine's for cogen use as well.

just wish i had natural gas where i am living now, but i guess i can wait till i relocate

bob g

[mobile_bob]

while this link may not shed much light on increased output or efficiency using Nat gas in dual fuel operation
it does clearly illustrate that it is not only possible to do so in an unaltered single cylinder engine, but one fairly typical
of what we use (S1100), and it is done in a fairly widespread manner.

http://www.ijens.org/97510-7373%20IJMME-IJENS.pdf

something anyone interested in dual fuel ought to download, read and add to their info library in my opinion

bob g

[Tom Reed]

I think you're on to something there Bob. Isn't the effect you've described similar to what the mfgrs are trying to accomplish by having multiple injection events during the combustion stroke on the new electronic injectors? Now I'm wondering of adding propane injection when the engine is loaded past a 3kw would be like adding nitrous to handle the over load and clean the cylinder at the same time. Add a pot to the governor and variable valve?

[Henry W]

Bob I like it. I will sit down tomorrow and re-read it. Just got home and I am to beat to do anything tonight.

Henry