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Go Back   TDIClub Forums > VW TDI Discussion Areas > Alternative Diesel Fuels (Biodiesel, WVO, SVO, BTL, GTL etc)

Alternative Diesel Fuels (Biodiesel, WVO, SVO, BTL, GTL etc) Discussions about alternative fuels for use in our TDI's. This includes biodiesel WVO (Waste Vegetable Oil), SVO (Straight Vegetable Oil), BTL (Biomass to Liquid), GTL (Gas to Liquids) etc. Please note the Fuel Disclaimer.

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Old January 25th, 2007, 21:32   #1
RareAir_Biofuel
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Default Biodiesel Heater System - revisited

OK, I posted something on this months ago, and since I didn't have much to say then, the post got ripped down. I'm back with the final results here... by the way, car is '03 Jetta wagon.

In the beginning, I was thinking of heating the whole system (tank, lines, filter, etc) like a SVO car. After looking at the power requirements for electrical and the amount of hoses etc for coolant heat, plus $$$$, those ideas crashed. So we spent some time pinpointing the problem to attack it directly. Figuring out the problem involved = run high % bio, freeze car up, and then figure out where it froze. Not too scientific, but it worked. The biggest help to this has been the procycle clear-blue lines I have under the hood. I found that the filter was NOT the problem - car starts, runs for 1-2 mile, then stalls out. I could see that the filter was moving fuel to the engine, probably because it gets so much heated return fuel from the engine (I've heard 9/10 of fuel goes right back). The problem, at least in my car and I would expect in many other TDI's, is further back. The filter was just not getting fuel. So it was the fuel line or the tank that was clogging. After another freeze-up, I took off the cap to the fuel sender unit, shook it around to knock off bio ice crystals, and poured some PS right down in there. Car ran like a dream after - turns out the problem is in tank.

Solution: got a heater element from PlantDrive
http://www.plantdrive.com/shop/produ...250&page=1then
Its a 12V element made by Racor, pretty simple design. Only takes a couple of amps, 85 degrees tops, not too expensive either. We figured theres no point in heating the whole tank, might as well get it right where its clogging - the sender unit screen. We imbedded element sideways in the platic box that the screen is carved into (pics to come, can't figure out how...) to put the heat right where the fuel enters the sender.

The switch to control the element went on the dash, where the ESP button is on nicer models. Plugged it right into the fuse box w/ the map light fuse. No worries about shorts that way.

To make sure the heated fuel gets to the engine, we replaced the crappy plastic fuel line with some Goodyear 3/8" insluated line. 3/8 was probably overkill, I'd use 5/16 next time, but the fuel seems to move to the engine much smoother now.

Total cost:

element: $55
fuel line: $25 for 25 feet, we used probably 10, but had to buy a whole roll.
Labor: not to hard to do it yourself, would probably take a day or so. I got SligShotSlug, an SVO conversion company here in Denver to help, since I'm not the most mechanically inclined.

Pics to come as soon as I figure out how, and I'll try to post updates on its effectiveness. I figure I can run B75 when its 40+ during the days (no garage or I'd be running B100), and B50 when it gets really cold.

EDIT:

Finally got some pics up, see at http://biodieselpictures.com/viewtopic.php?p=624#624

Last edited by RareAir_Biofuel; February 6th, 2007 at 21:04.
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Old January 26th, 2007, 02:47   #2
RC
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Nice work, looking forward to the pics. I've always known the fuel sending unit to be a bottleneck but am reluctant to go to measures beyond winterizing our fuel to B80.

Sad thing is, car manufactrers could offer a foolproof OEM fuel heating system and option it for about $100. Insulate and heat the tank, fuel lines, and filter and we're on our way. Perhaps one day.
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Old January 26th, 2007, 04:47   #3
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That sounds great! Can't wait to see the pictures.
Can you show how & where you made the junction to insulated lines from the sendng unit, too? It's a pretty tight fit back there, as I recall. Does the larger line make the bends without kinking?
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Old January 26th, 2007, 05:37   #4
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Quote:
Originally Posted by RareAir_Biofuel
...we replaced the crappy plastic fuel line with some Goodyear 3/8" insluated line.
I'm interested in seeing how this line holds up to B100.
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Old January 28th, 2007, 17:26   #5
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This is exactly what I've been looking for. Anyone know of a company that would do this sort of thing in New England?

Now, what's the possibility of setting up a timer and thermometer so it'll run a little before your usual drive time *if and only if* it's below a certain temp outside? Being able to automate this is key here so I can convince my buddies to go bio, too. They're a little lazier than I .
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Old January 30th, 2007, 10:46   #6
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Jury's still out on the fuel line issue - I don't know if its as big of a problem as people say. I think when biodiesel causes problems with a hose, the hose is already cracked internally or of poor construction. We went with the Goodyear since 1) its some of the best hose made, 2) its insulated, unlike the polyurethane hoses, and 3) is a heck of a lot cheaper than Viton. Installing it took less than an hour, and a new hose would be easy to put in if this one starts sweating. Big improvement over the OEM hose, thats for sure.
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Old January 30th, 2007, 11:34   #7
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Quote:
Originally Posted by RareAir_Biofuel
... We went with the Goodyear ...
I've got a big Goodyear supply hose on our 500 gallon storage tank. It's been pumping B80/B100 for 7 years now... sweating the last two or so but still holding up quite well. We'll see how long before I have to replace it.
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Old January 30th, 2007, 12:54   #8
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Default Did you replace the elbows?

When you replaced the stock fuel line did you eliminate the 90 degree elbows as well?

I have had similar experiences as you. When I investigated where the problem was I also observed that the fuel filter was not the problem. I tested trying to pull fuel from the sending unit and I did have success there. When I tried to pull fuel through the line I found that the line was plugged. I blew the clog out of the line and from the results I believe the clog occured at an elbow.

In my opinion, in order to cold start with bio the first issue is making the cold bio fluid enough to even start. After that the next problem is getting the cold fuel to flow from the tank to the motor. Any locations that can collect frozen particles will quickly cause a clog. The fuel screen, check valve, and elbows have proven to be problem locations.

I like your idea of heating the fuel at the fuel sending unit, but the initially cold fuel in the line still has to make it to the filter without plugging. Replacing the 90 degree bends with more gradual radius curves should allow slushy fuel to still flow to the filter. I would replace the return line and drill out the return check valve for the same reason. Intially this fuel will be cold. The hot return fuel must push the cold fuel back to the tank. The cold fuel in the line could still plug at an elbow or check valve.

In one test I performed it took over 5 minutes of driving for the reported fuel temp in VAGCOM to climb from -10C to 0C due to the recirculating heating alone. Assuming the cold fuel in the line makes it to the filter without plugging then the heated fuel from the heater in the sending unit should keep the filter from plugging and speed up the heating of the filter.

The pump at my local retailer of bio has frozen up so unless we have an above freezing day I will have to run D2 for the rest of the winter.
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Old January 30th, 2007, 14:47   #9
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Yeah Mon!
You saved me a ton of research. The weather is cold here in Idaho and we can't aways find Canola stock, which tends to hold it's own in the cold weather. I heard linseed does really well too but I have not found any in the recycled market.
I had been looking for a back-up heating system. Thanks for the post Rare Air!
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Old January 30th, 2007, 16:43   #10
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I've heard of a few people here in the UK who have installed insulated electric heating all along the fuel lines. It works like an electric blanket. They switch on before they start, wait a short while for things to warm up a touch, then start the engine and leave the electric fuel line heating on for a few miles to allow the fuel plenty of chance to warm due to the electrical and engine heating.
This was a long time ago, and I think it was for running BioFuel as opposed to Biodiesel, but would of course be great for BD in the cold.
Anyone heard of this or done it?
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Old February 1st, 2007, 15:19   #11
RareAir_Biofuel
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Answers to 2 questions:

RC- Denver Biodiesel, the local co-op, also has a big 'ol Goodyear fueling hose, which has been in operation only 6 months but looks to be doing a solid job. Bought on recommendation from several experts.

JeffMX5- yes, the line does repace all 90 degree elbows except the one right at the top of the fuel sender unit. The only place this gets sticky is where it has to go from the top of the fuel tank to under the car. We had to use an uninsulated poly hose for this part, it was the only thing with an O.D. small enough to get through there. If you were OK with cutting a piece of the body sheet metal out (hidden from view by the back seats), you could run as big a hose as you want without kinking. Up front, the fuel line goes through a ~2x3 inch housing that makes a nice easy bend up to the engine. No problems pulling hose through there. Overall, flow is great, which should make life easier on the injection pump (TDI's are on a vaccum system, no fuel lift pump).
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Old February 2nd, 2007, 08:56   #12
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excellent research Rare.

i've been reading posts about fuel addatives and heating systems for a while, this one seems pretty good to me. i want to run B100 year round so i'm gonna need some a pretty hard core heating setup.

i notice you're in Devner and you're got the SVO company to help you out. if i were to take a weekend trip up that way, would you be willing to teach me the process you used? we've got the Kansas City GTG coming up at the end of March and i'd love to be able to teach this mod to people there.

let me know if a weekend workshop would work out for you, thanks.
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Old February 4th, 2007, 20:45   #13
RareAir_Biofuel
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Sure thing Mr Erlo. We could run it through Denver Biodiesel, the co-op that holds all of these factions together. I'll bet Kirby at SlingShot Slug, the SVO guru, would be happy to explain the systems. You can give him a call at (303) 435-7479.

That said, my system is rather simple, and wouldn't hold up to more that B50 in these Colorado winters (below 0F ~10 nights a year, and 10-30 most of therest of the winter). To expand on the system I have, a filter heater by Racor or Stanadyne would complement nicely, and can be run off the same circuit. The beauty of these systems is their tiny energy draw, they don't require a second battery/plug ins. Using the hose for insulation helps utilize the heating power of these tiny elements. Kirby has some systems that are way better, B100 all the way!

**Still trying to figure out how to post pics, any help there???
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Old February 4th, 2007, 21:13   #14
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RareAir,

you can put up pictures for crossposting, at www.biodieselpictures.com ('m sure there's some kind of 'miscellaneous' category that this would fit into)
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Old February 5th, 2007, 09:39   #15
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Default Calculations

I was curious so I got out my physics book this weekend and performed some math. I am an Electrical Engineer so this was actually fun .

I have seen several heaters for 12V systems that dissipate 100W. I was curious how quickly that would raise the temperature of the fuel. I was able to find the specific heat of D2 on the web and I assumed bio has the same specific heat.

I started with an assumption for maximum fuel flow rate. I assumed traveling at 90mph and achieving 34mpg while doing it. This equates to 10 liters per hour of fuel used. 100W for 1 hour is 360kj. This will raise 10l of fuel by 21C. ( I have skipped a bunch of interviening math )

90 mph in the dead of winter is unrealisticly fast for me so I took a more typical case. 60mph and achieving 45mpg. This equates to 5l/h and therefore 42C rise.

If the starting temperature is -40C then a 100W heater will heat the fuel to 2C (above or at the cloud point of bio) under normal highway conditions.

Now what about idle or low volume usage? I don't know what the fuel usage is at idle but I believe it is reasonable to assume it is at least 10 times less than steady state highway speeds. 0.5l/h would give a 420C rise.

This shows the need for a thermostatic control built into the heater. If a 100W heater is installed in the fuel tank then convective circulation should keep the element from overheating until all the fuel in the tank is too hot. Another concern with an in tank heater is what happens to the heater when the tank is low on fuel and sloshing uncovers the element for a moment. The element must not be allowed to get hot enough to ignite the fuel when it sloshes back. In the confines of a fuel filter a 100W heater element is only cooled by the fuel flow over it. At idle the small volume of fuel flowing over the element will over heat very quickly if the heater runs at full power.

This is why companies like Stanadyne have a thermostatic control built into the heating element. Any electric heating element you add to your TDI must have a thermostatic control built in otherwise you run the very real risk of starting a fire.

Based on the expected flow rates of our TDIs 100W heaters appear to be appropriately sized. At 50W there might not be enough heat rise at highway speeds to warm the fuel enough.

This analysis does not take into account the heat of solidification (the heat required to melt frozen particles). If there is some crystalization in the fuel (clouding) the heat required to melt that crytalization will reduce the resultant temperature rise.

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