View previous topic :: View next topic |
Author |
Message |
:) Mud Obsessed
Joined: 06 Feb 2006 Odometer: 4337 Location: Norfolk
1995 Land Rover Defender
|
Posted: Fri Dec 14, 2007 6:25 am Post subject: Vegtable oil and temperature
|
|
|
I'm running about 10% veg at the moment, with a percentage of bio-diesel when I can find it.
I was musing, as you do, about the problems of ring gumming when using vegetable oil. I was thinking about alternative heating methods to get the oil hot and wondered if fitting an electrically heater to the pipes just before the IP and injectors would be beneficial. I was considering this mainly becasue from an electrical point of view it would be quite easy to retrofit a clamp on heater.
What I couldn't establish was whether the gumming problem is fuel temperature dependant (ie injectors don't spray properly) or combustion chamber temperature problem (ie condenses on the cylinder bores). Can anyone provide guidance on this.
More generally why does the oil gum things up when cold?
--
Tim.
__________________________________ -- Timothy Birt -- |
|
Back to top |
|
|
|
Nathaniel Difflock Royalty
Joined: 13 May 2003 Odometer: 17901 Location: North, North Yorkshire
1979 Suzuki LJ
|
Posted: Fri Dec 14, 2007 8:00 am Post subject:
|
|
|
You are correct - and Direct injection engines are more prone - Cold veg is too thick to inject properly, it doesn't spray from the injector properly, therefore it doesn't burn properly and sticks to cold bits of metal like the head, piston and bores.
You can clamp as many heaters to the fuel lines as you want but its the cold starts that do the damage.
Twin tank is the only way to go with a TDI.
Oh and electric heaters aren't worth a jot anyway, Flat Plate Heat Exchanger is the only way to go....
__________________________________ Nat
If You Open Your Mind Too Much Your Brain Will Fall Out |
|
Back to top |
|
|
stevieboy118 Articulating
Joined: 11 Oct 2004 Odometer: 610 Location: Plymouth, Devon
1985 Suzuki SJ
|
Posted: Fri Dec 14, 2007 9:37 pm Post subject:
|
|
|
Nathaniel Ham wrote: | Oh and electric heaters aren't worth a jot anyway, Flat Plate Heat Exchanger is the only way to go.... |
Seconded, electric heaters are kak. For cold starts it doesn't matter how much heat you put into the fuel lines, when the oil gets to the stone cold injectors (with the huge heatsink shaped like a stone cold engine) the heat will be gone.
Twintank and heatexchanger is what you need. Flatplate or coil type.
__________________________________ Breaking - SWB Frontera, PM me if you need any bits! |
|
Back to top |
|
|
markyb Off-Road Guru
Joined: 27 Jan 2004 Odometer: 1188 Location: Hampshire
|
Posted: Tue Dec 18, 2007 7:34 pm Post subject:
|
|
|
im running second tank for my veg oil. i let the engine heat before i switch over.
im using an electric in line heater to heat the veg oil too it works of a couple of glow plugs has a thermostat so it heats oil to 80 as veg oil heated over 70 burns the same as diesel. but engine needs to be warm
have no issue with the electric heater ive done a fair few miles now on veg even in this cold weather we have had the last few weeks.
i always run down the last 3 miles on diesel to clear the pump i have an electric change over valve
one thing i have found is there are a lot of opinions on this veg oil thing, a lot of crap and a lot of good,
|
|
Back to top |
|
|
Nathaniel Difflock Royalty
Joined: 13 May 2003 Odometer: 17901 Location: North, North Yorkshire
1979 Suzuki LJ
|
Posted: Tue Dec 18, 2007 9:08 pm Post subject:
|
|
|
Mark, any chance you can put a temp probe measuring the temp of the fuel leaving the injection pump when its all up to temp?
even an IR thermometer pointed at the pipe will work to give us a rough reading.
__________________________________ Nat
If You Open Your Mind Too Much Your Brain Will Fall Out |
|
Back to top |
|
|
markyb Off-Road Guru
Joined: 27 Jan 2004 Odometer: 1188 Location: Hampshire
|
Posted: Tue Dec 18, 2007 10:14 pm Post subject:
|
|
|
yeah will do i had a little video of it in action reading the temp but cant find it.
but here is a pic of it . might be a while finding a temp gauge,
bought it from www.vow2.co.uk the twin plug type but you can buy ones with a coolant ways but i figured i would go just glow plugs
i also run the Pollark change over valve. will soon be up to 2000 miles doing a fair few a week at present,
|
|
Back to top |
|
|
Nathaniel Difflock Royalty
Joined: 13 May 2003 Odometer: 17901 Location: North, North Yorkshire
1979 Suzuki LJ
|
Posted: Tue Dec 18, 2007 10:27 pm Post subject:
|
|
|
Looks like a pretty good job, the good thing is with a Bosch pump you don't really need that much heat, Its cold cylinder walls that attract unburnt veg, so once its running and warm you can feed it pretyt much anything!
__________________________________ Nat
If You Open Your Mind Too Much Your Brain Will Fall Out |
|
Back to top |
|
|
markyb Off-Road Guru
Joined: 27 Jan 2004 Odometer: 1188 Location: Hampshire
|
Posted: Tue Dec 18, 2007 10:29 pm Post subject:
|
|
|
meant to add the whole system after about 20 mins gets pretty warm the returning oil heats the tank , didn't realize how much oil returns on tick over,
i ran cooper pipes down the exhaust side of the chassis to aid in the heating they don't touch but figured it would help if it was frozen. but -5 it didn't freeze, Ive heard people saying no to using cooper and yes to using cooper, but keep the lines full but watch out for waste, ive used both now but only small amount of waste mixed with fresh, i suppose maybe the acid in the waste, so pretty much sticking to New now as its messy and hassle filtering the SPAM out the waste
seems like its a learning curve at present but its working ok, i bought an older disco so any long term issues it wont matter,
pic of the switches
|
|
Back to top |
|
|
markyb Off-Road Guru
Joined: 27 Jan 2004 Odometer: 1188 Location: Hampshire
|
Posted: Tue Dec 18, 2007 10:34 pm Post subject:
|
|
|
i suppose letting the engine warm is going to prevent the gumming,
shame that change over valve didnt do a sort of position, where you could do a mix. like 90% on veg 100% on derv, or 50 50
you could then mix it in until warm or what ever suited at the time
be interested to see how you filtering goes Nat, i certainly need to refine my setup. its a pain, only thing i find is the cold weather tends to make the SPAM go hard at the bottom so it separates nice
|
|
Back to top |
|
|
:) Mud Obsessed
Joined: 06 Feb 2006 Odometer: 4337 Location: Norfolk
1995 Land Rover Defender
|
Posted: Wed Dec 19, 2007 7:07 am Post subject:
|
|
|
Thank you guys - this is very informative.
Nat, you have given me the definitive answer I was looking for, the oil condenses on the bores, so the cylinders have to be hot.
Out of interest I will work out the electrical energy is required to heat the fuel oil.
--
Tim.
__________________________________ -- Timothy Birt -- |
|
Back to top |
|
|
|
:) Mud Obsessed
Joined: 06 Feb 2006 Odometer: 4337 Location: Norfolk
1995 Land Rover Defender
|
Posted: Wed Dec 19, 2007 7:31 am Post subject:
|
|
|
Just been googling for the specific heat capacity of SVO and I'm getting quite a range, 1.67 to over 2. There is some suggesting suggestion that it increases with temperature.
Anyway I will take some 'worst case scenario'; assuming that it is 2kJ/kg.K which is on the high side and that the fuel consumption is 10kg/hr and that we need to heat the fuel by 70°C the energy required is:
390W
With is a fair bit to suck out of the alternator, but within its capabilities.
Scale the result appropriately for different scenarios
--
Tim.
__________________________________ -- Timothy Birt -- |
|
Back to top |
|
|
markyb Off-Road Guru
Joined: 27 Jan 2004 Odometer: 1188 Location: Hampshire
|
Posted: Wed Dec 19, 2007 8:33 am Post subject:
|
|
|
so we can say its safe to say warm engine and heating the oil s the better way
|
|
Back to top |
|
|
Nathaniel Difflock Royalty
Joined: 13 May 2003 Odometer: 17901 Location: North, North Yorkshire
1979 Suzuki LJ
|
Posted: Wed Dec 19, 2007 12:49 pm Post subject:
|
|
|
Tim, You'll find that the fuel pump circulates TEN times the amount of fuel that the engine uses, You've based your calcs on 10L fuel an hour, however you need to factor for at LEAST 100L an hour...
2000W is about the figure that most arrive at, thats 20 glow plugs for an electric heater......
A Flat Plate heat exchanger is a much better proposition - seeing as you're letting the engine warm up anyway.
http://www.biotuning.co.uk/ShopHeatExchangers.htm
The 49quid is the one I have and its excellent, I've not done a temp check for a while but IIRC I was seeing about 48*c at the pump output..
__________________________________ Nat
If You Open Your Mind Too Much Your Brain Will Fall Out |
|
Back to top |
|
|
markyb Off-Road Guru
Joined: 27 Jan 2004 Odometer: 1188 Location: Hampshire
|
Posted: Wed Dec 19, 2007 12:56 pm Post subject:
|
|
|
only issue i saw with filter coolant type heaters is ,
when you switch to diesel you dont want to heat diesel so you would have to have the filter heater only on the veg system and away from the diesel , so its not heating it as close to the injector pump as it could be.
I will order a temp gauge as i think 20 glow plugs would be a abit over the top as i will need to keep an eye out for when my glow plugs die.
im getting hot oil back into my tank so 2 plug system is heating will be nice to know what temp its running at the heater casing almost is untouchable when running,
|
|
Back to top |
|
|
Nathaniel Difflock Royalty
Joined: 13 May 2003 Odometer: 17901 Location: North, North Yorkshire
1979 Suzuki LJ
|
Posted: Wed Dec 19, 2007 1:04 pm Post subject:
|
|
|
On the contrary, Hot diesel does not harm at all, Common rail engines make the diesel VERy hot when the pressure it up...
I ran diesel through my Heat ex for a tank full and it had MORE lower and used less fuel, Quite a lot less!
I'd fit a FPHE to every car!
__________________________________ Nat
If You Open Your Mind Too Much Your Brain Will Fall Out |
|
Back to top |
|
|
cieranc Just got MTs
Joined: 20 Mar 2005 Odometer: 451 Location: Darlington
|
Posted: Wed Dec 19, 2007 1:29 pm Post subject:
|
|
|
I currently run a FPHE off a winterized KTM bike, alongside a silicon filter heater band, this one to be exact: http://www.dieselveg.com/bio-band_band_heater.htm
I did a lot of experimenting on my Def 200 TDi and heres the steps along the way to my current setup:
50/50 svo to derv, engine would run but difficult to start, waxing at the filter leading to loss of revs, lots of grey/white smoke with engine cold, poor idle.
20/80 svo to derv, engine would run, cold starts better but white smoke and poor idle when cold.
FPHE added, same mix, same symptoms when cold (as expected), fine when hot.
FPHE + Silicon band added, 20/80, started fine, very little white smoke, good cold idle.
FPHE + Silicone band, 50/50 same as above.
FPHE + Silicon band, 80/20, difficult to start initially (oil in filter-pump pipe), but good idle once started, slightly more white smoke when cold, reasonable cold idle.
FPHE + Silicone band, 70/20/10, SVO/Derv/Petrol with a drop of acetone. Engine starts within the first few turns of the starter, very little smoke, good cold idle. Slight loss of power top end.
10% petrol is proven to halve the viscosity of the oil, making for easier pumping, finer atomization and a better spray pattern, though reduces the cetane number of the mix resulting in a loss of power and a slightly lower mpg.
This has all been in cold, sharp frosty weather.
My current fuel I mix 20 ltrs at a time, 14l trs SVO, 4 ltrs Diesel, 2 ltrs Petrol, acetone I get for free, and works out at 72ppl at current prices.
I understand a pure cetane booster (VeggieBoost seems to be highly spoken of, http://www.vegetableoildiesel.co.uk/veggiboost.html ) will combat the loss of power at the top end, by restoring the blends cetane number reduced by adding the petrol. This added to my mix would make it 75ppl.
The filter band gets very hot very quickly (its too hot to touch before the glow plug light goes out), only pulls 200w, and there is a massive difference on cold starts if it is on or off, there's white smoke with it turned off. Once the engine is up to temperature, I switch it off as the FPHE is doing its thing then.
Monitoring consists of daily check of engine oil to gauge ring wash and a weekly check of the glow plugs to get a gauge of coking.
Last edited by cieranc on Wed Dec 19, 2007 2:02 pm; edited 4 times in total |
|
Back to top |
|
|
:) Mud Obsessed
Joined: 06 Feb 2006 Odometer: 4337 Location: Norfolk
1995 Land Rover Defender
|
Posted: Wed Dec 19, 2007 1:35 pm Post subject:
|
|
|
Nathaniel Ham wrote: | Tim, You'll find that the fuel pump circulates TEN times the amount of fuel that the engine uses, You've based your calcs on 10L fuel an hour, however you need to factor for at LEAST 100L an hour... |
Are you sure? This seems an awful lot and above the capacity of some electric lift pumps.
I have 'accidentally' removed the spill return and there wasn't much fuel going through it. If this is a significant problem then it might be better to have a small header tank at the front and feed the spill return into that, so that the heated oil can be recirculated.
BTW: Good link to the heat exchanger, I like the price!
--
Tim.
__________________________________ -- Timothy Birt -- |
|
Back to top |
|
|
markyb Off-Road Guru
Joined: 27 Jan 2004 Odometer: 1188 Location: Hampshire
|
Posted: Wed Dec 19, 2007 1:50 pm Post subject:
|
|
|
ive read in a number of places that hot diesel looses some off its lubricating properties so long term damage will occur. must of the heated fuel lines systems tend to use a different grade of diesel. so heating wont effect, i think it something to do with the temp so if you heat diesel to the same temp as your veg you may cause long term damage.
i cut and paste this from Vow2 site. will add more if i come across it but i turn my heater off before going back to diesel.
.......................................................................................
Firstly decide if your engine is capable of running on veg oil.
Next decide how much oil you intend to use.
Now the tricky bit. The faster the fuel flow and the higher the % of oil the bigger the heater. If you can fit the D or DW as they offer the best heating. For example a 2L Bosh pump works well on a D+ unit. While 1.6L on 60% works well on a C+ unit. I cannot advise you as to which unit is best for you as it depends on so many variables. What works on one car might not be as good on a similar engine.
As about, check on the forum. Fit the biggest heater you can.
You should have your battery and alternator checked before fitting. This ensures you wont have a flat battery.
You should also ensure ALL engine glow plugs are working well otherwise starting will be more difficult.
You might consider have your injectors cleaned.
for those that havant seen it the types of heaters mentions have coolant ways to help in the heating
E and F and DW units cannot be fully turned off so are unsuitable if you intend to use 100% diesel at any point. Heated diesel looses its lubrication and must have some veg oil mixed with it. 10% should be enough.
|
|
Back to top |
|
|
Nathaniel Difflock Royalty
Joined: 13 May 2003 Odometer: 17901 Location: North, North Yorkshire
1979 Suzuki LJ
|
Posted: Wed Dec 19, 2007 3:19 pm Post subject:
|
|
|
Quote: | The filter band gets very hot very quickly (its too hot to touch before the glow plug light goes out), only pulls 200w, and there is a massive difference on cold starts if it is on or off, |
You mut be getting near the Cold Filter plugging point then, as no heater will affect the temp of the veg in the HP fuel lines...
Well apart from the Injector pipe heater - but thats a lot of money...
Quote: | E and F and DW units cannot be fully turned off so are unsuitable if you intend to use 100% diesel at any point. Heated diesel looses its lubrication and must have some veg oil mixed with it. 10% should be enough |
The guy selling the VOW heaters is flattering himself if he thinks the coolant passing through an alloy block next to some fuel will heat the diesel any.
You might as well use a coolant heater than an electric heater which in turn puts strain on your alt and battery and reduces MPG.
Coolant heat is all wasted heat...
As for fuel return set your engines revs to cruising speed, 2800? and pull off the return from the pump (NOT the injector leakoff pipe!)
My Fourtrak emptied a 10L tank in about 10 mins at 2500rpm when I had 2 pipes crossed.
As for Hot Diesel
These common rail engines get the diesel so hot that a lot of them put the return fuel through a cooler before returning it so it doesn't damage the plastic fuel tank!!!!
__________________________________ Nat
If You Open Your Mind Too Much Your Brain Will Fall Out |
|
Back to top |
|
|
markyb Off-Road Guru
Joined: 27 Jan 2004 Odometer: 1188 Location: Hampshire
|
Posted: Wed Dec 19, 2007 4:03 pm Post subject:
|
|
|
like i said above a lot of good info and some not so good info around the different forums Ive tried to take a lot of opinions and find a trend on the info and make up my own mind,
but i was thinking injector pump lub over engine bits
Will see how the 200tdi is after a year of running it and 30,000 miles.
but i agree the coolant type heater with the glow plugs wasn't worth it as by the time the coolant heats up it not going to make too much difference to the fuel.
I will drop back to let you know what the operating temp is of the oil .
|
|
Back to top |
|
|
|
:) Mud Obsessed
Joined: 06 Feb 2006 Odometer: 4337 Location: Norfolk
1995 Land Rover Defender
|
Posted: Wed Dec 19, 2007 4:18 pm Post subject:
|
|
|
Nathaniel Ham wrote: | You might as well use a coolant heater than an electric heater which in turn puts strain on your alt and battery and reduces MPG.
Coolant heat is all wasted heat...
As for fuel return set your engines revs to cruising speed, 2800? and pull off the return from the pump (NOT the injector leakoff pipe!) |
Agreed, best option is to use waste engine heat for bulk heating of fuel.
I thought the IP return was simply done to self prime the system, but now I'm understanding more of what is going on perhaps it is to keep cool fuel circuiting in the IP. No matter what the situation I feel it would be an idea to seriously restrict the return flow, this means is that the lift pump needs to be happy pushing into a high pressure. I know some lift pumps are OK to do this as all that happens is that the diaphragm doesn't move so far.
Still thinking that a small fuel header tank is a reasonable option.
Nat, You mentioned "Injector pipe heater" which is exactly what I was considering when I started this thread. Incidentally it would also avoid the IP return problem. I can definitely build an electrical device to heat the high-pressure pipes, either by induction or simple resistance heating.
Do you have any more information on this?
--
Tim.
__________________________________ -- Timothy Birt -- |
|
Back to top |
|
|
Nathaniel Difflock Royalty
Joined: 13 May 2003 Odometer: 17901 Location: North, North Yorkshire
1979 Suzuki LJ
|
Posted: Wed Dec 19, 2007 4:52 pm Post subject:
|
|
|
On my conversion I did away with the return to the Veg tank and "T" Peiced it back into the the supply pipe just before the FPHE so the fuel circulates and gets as hot as possible as well as fixing the problem I had with fuel starvation at high RPM's because the fuel tank pickup is a bit restrictive.
Induction heating.
Its a really interesting bit of kit, and has apparently produced some REALLY good results.
Make one for me whilst you're at it
__________________________________ Nat
If You Open Your Mind Too Much Your Brain Will Fall Out |
|
Back to top |
|
|
markyb Off-Road Guru
Joined: 27 Jan 2004 Odometer: 1188 Location: Hampshire
|
Posted: Wed Dec 19, 2007 5:09 pm Post subject:
|
|
|
as for Ting in the return i noticed the return rate on tick over was a lot on my 200tdi. will the lift pump just slow down or will it effect it in anyway?
i went for a return just improve things on the heating side i figured warm oil returning to the tank would help the system once it was running for a while.
|
|
Back to top |
|
|
Nathaniel Difflock Royalty
Joined: 13 May 2003 Odometer: 17901 Location: North, North Yorkshire
1979 Suzuki LJ
|
Posted: Wed Dec 19, 2007 6:30 pm Post subject:
|
|
|
Looping the return won't pressurise anything, nor slow the lift pump down.
The fuel just goes round and round and as it is used by the engine the suction just brings a little more up from the tank as it needs it.
__________________________________ Nat
If You Open Your Mind Too Much Your Brain Will Fall Out |
|
Back to top |
|
|
Nathaniel Difflock Royalty
Joined: 13 May 2003 Odometer: 17901 Location: North, North Yorkshire
1979 Suzuki LJ
|
|
Back to top |
|
|
:) Mud Obsessed
Joined: 06 Feb 2006 Odometer: 4337 Location: Norfolk
1995 Land Rover Defender
|
Posted: Fri Dec 28, 2007 12:07 pm Post subject:
|
|
|
Induction heating isn't particularly hard, it requires some high power electronics, but they are not expensive. The process is no more than a high frequency power oscillator which drives a coil of wire. OK maybe not quite that simple as you have to get the frequency and impedance correct, specifically the inductance and capacitance need to be tuned.
This thread came about from me thinking via the keyboard really, however let's take it a bit further...
What about induction heating the HP injector pipes? They are made of steel which is an excellent material to heat via induction. They long enough so that there is a lot of time to move the heat from the steel into the fuel oil. The system could be easily retrofitted, without even disconnecting the injector pipes by simply wrapping a thick copper wire around the pipe, it would need high temperature insulation (PTFE maybe?).
Is there sufficient benefit to make this worth trying, or perhaps more conventional resistance heating would be easier?
EDIT: OK, now I have read the link Nat provided above it seems nothing I'm dreaming about here is new. The price at £187.19 is probably right for a low production run item, but it could be much lower in quantity. As I said above the electronics are not hard.
--
Tim.
__________________________________ -- Timothy Birt -- |
|
Back to top |
|
|
markyb Off-Road Guru
Joined: 27 Jan 2004 Odometer: 1188 Location: Hampshire
|
Posted: Sat Jan 12, 2008 12:48 pm Post subject:
|
|
|
finally got my cheap £3:99 IR probe thingme and i get a temperature reading of 57 degrees C on the pipe. going into the injection pump
I ran the motor so it was warm , I need to try and calibrate it so i can get a true reading it appears to be under reading . so happy that its heating the oil to around the right temperature.
|
|
Back to top |
|
|
DiscoJack Gate Opener
Joined: 25 Jun 2007 Odometer: 42 Location: Middx
|
Posted: Thu Jan 17, 2008 8:54 pm Post subject:
|
|
|
I know some lift pumps are OK to do this as all that happens is that the diaphragm doesn't move so far.
Still thinking that a small fuel header tank is a reasonable option.
Does anyone have info on the lift pump issue as i am thinking of using two totally separate fuel supply / filters with the 3 way valve after the lift pump and using an electric pump for the SVO but this will mean that the mech lift pump is pumping into a closed valve while on SVO. Will it die?
|
|
Back to top |
|
|
markyb Off-Road Guru
Joined: 27 Jan 2004 Odometer: 1188 Location: Hampshire
|
Posted: Tue Jan 22, 2008 9:30 am Post subject:
|
|
|
found the down side to using this electric glow plug heater , its like having your air con on all the time so ive lost about 3 or 4 mpg when its on,
thinking i will upgrade to a combined coolant and glow plug arrangement as i do like the fact the glow plugs are heating the oil from 2 secs after i switch it on..
|
|
Back to top |
|
|
|