Has anybody done a comparison between Veggie Oil and Bunker Oil?

Both are more viscous than D2 or Kerosene.

Preheating, of course, is important for running bunker oil. Perhaps the engines running it also have slower RPM's.

quote:

Originally posted by danalinscott:

quote:

So, it would be possible to boost the operating temperatures of one's engine to 250 degrees or so by changing the thermostat, and increasing the antifreeze content in the coolant.

I don't believe this will work.
First ... it will be very hard to find a [250]F termostat.
Second increasing the antifreeze content of the coolant mix will not increase its' boiling point.

True,

It might be hard to find "off the shelf". But, I believe that "when there is a will... there is a way". It shouldn't be too hard to change an electronic fan to not kick in until the temp is raised. Of course, the fan is only used for around town driving, and not highway driving.

As far as coolant boiling points:

Water BP: 100C, 212F (at STP, higher if under pressure).
Ethelene Glycol BP: 197C, 387F
Propylene Glycol BP: 188C, 370F
I believe the boiling points fall quickly when "wet". However:

Ethelene Glycol -
3.4% H2O, BP: 184.2C, 364F
6.5% H2O, BP: 178.6C, 353F
10.2% H2O, BP: 167.4C, 333F
21.6% H2O, BP: 142.5C, 289F


DOT 3, 4, and 5.1 Brake Fluid are also all polyethylene glycol Fluids. They seem to be somewhat corrosive (DOT5 is supposed to be less corrosive, but is silicone based). Anyway, they share many similarities with antifreeze.

.............Dry boiling point....Wet boiling point(3.7% water)
DOT 3.....205°C (401°F)........140°C (284°F)
DOT 4.....230°C (446°F)........155°C (311°F)
DOT 5.....260°C (500°F)........180°C (356°F)
DOT 5.1..270°C (518°F)........191°C (375°F)

One of the issues that I'm seeing is that the specific heat capacity of Glycols can be much lower than water. I.E. Less cooling, or less capacity to wick heat away from the "hot spots" in the engine.

Specific heat capacity water (STP?) is 1, I think.
100% Ethelene Glycol at 200F - 0.66
100% Ethelene Glycol at 285F - 0.71
65% Ethelene Glycol at 240F - 0.828

Specific Heat Capacity Propylene Glycol
60% Propylene Glycol (? Temp) - 0.805 Specific Heat.

Anyway, with common antifreeze solutions, it should be possible to support engine temperatures in excess of 250F.

quote:

Originally posted by keelec:
Anyway, with common antifreeze solutions, it should be possible to support engine temperatures in excess of 250F.

You are going to have to design a properly clearanced engine to support this temperature. In a standard engine at 250F your pistons will start getting too tight for the cylinders, lose lubrication and fail quickly.

Dana, I think you're missing Ed's point entirely: Higher temps. than 80*C may certainly optimize combustion of SVO, but we need more data to verify how, what, when, where, why, etc. And it may also flush out in the end that 80*C is the best "practical" option given the limitations of heating to higher levels. But this is all speculation Mr. Linscott. The only thing we have right now is real world practical experience and we know that cold SVO doesn't work so well, and that 80*C SVO works quite well. Does 250*F SVO work significantly better than 80*C SVO? We don't know, it's all speculation at that point. You seem to think it does, Ed thinks it's moot. We have no way to know for sure until a peer-reviewed study gets published and then gets replicated multiple times by other researchers to verify the results. That's how scientific inquiry works. Being a skeptic is part and parcel to the scientific investigator, as evidenced by the testing of the null hypothesis in all inquiries, not the other way around.

Remember the words of former Defense Secretary Donald Rumsfeld, "We know what we know, we don't know what we don't know, and we don't know what it is we don't know." Or something like that.

Rummie wisdom, take it or leave it.

justin

This message has been edited. Last edited by: Shaun,

quote:

We don't know, it's all speculation at that point.

Actually it isn't all speculation.

If there were NO studies at all that supported the commonly held theory (devloped as a result of the results of the U of Idaho research on Vo fuel) that injectors designed for optimum atomization of fuel the viscosity of diesel fuel will work best if fed VO of that same viscosity it would be all speculation.

But there are.
The only speculationhere is that this theory only holds true to 160F and no higher.

And up until now only one or two kit vendors did not subscribe to the "less viscous is better" theory. Those that did not seemed to oppose nearly every advancement in VO fuel conversion technology that was discovered.

Now however a kit vendor that has stead fastly subscribed to the "hotter is better" theory has reversed their position. What changed?

There is no study that supports 150-160F is better than 130-140F .. yet they embraced THAT as a fact. Why? Because they were able to achieve those temperatures with common of the shelf (very cheap at wholesale level) components. And they do not have access to the technology to allow their kits to heat VO to temp shigher than 160F temps.

I hate to be too cynical...but I wager that as soon as they have that capability they will do an abrupt "about face" on this issue.

80C is 176F.
90C is 194F.

What about cetane as an important characteristic of fuel, so important that every engine maker has a spec. for it. Adjusting timing is one easy way to compensate for the lower cetane of VO. Here is your quote:

"If you can optimise VO fuel to match diesels vsscosity no timing change is neccesary for the engine to be optimized for BOTH fuels. In this way you can obtain the "good effects" of advancing the injection timing..without the bad ones."

ACREVO says that they got less power and mileage from VO than D2.

I see nothing in ACREVO about cetane or ignition delay, except this:
"Finally variations were made in the fuel injection system of the test engine used in order to reduce the specific disadvantages of vegetable fuels", but they don't specify what those variations were at that point.

Later in the summary, they mention they advanced the timing ("start of pump delivery"), and got good improvements, just as I and many others have found:
"Nozzle position and start of pump delivery can be changed at the same time, so that both effects add up giving a reduction of up to 75 % of the original value." but they don't say whether that was improving power or emissions or both.

Any studies to back up your claim that raising the temp from 170F to 230F will compensate for the lower cetane of VO? The ACREVO quotes above seem to contradict your claim.

you boys should watch this video

http://www.youtube.com/watch?v...7Hfg&feature=related

Scene From the movie A Christmas Story where Flick gets his tounge stuck to a flag pole.

take a walk or something

Omar
www.omarsales.com

As a full-time diesel mechanic and long time installer of SVO systems (since 2000), it's clear to me that the viscosity of the fuel is perhaps the most important piece of the SVO puzzle, and ideally this should be as close to that of diesel fuel. What temperature that happens at I don't really know to be honest, but I'm sure it's not a simple single number and instead depends on a bunch of variables such as: oil type, iodine #, etc. I also know that the temperature at the time of injection is far more important than the temperature of the fuel entering the injection pump, so that's worth pondering also. A laser temp gun will get you close, but the actual temperature of the atomized fuel at the moment of injector opening is more interesting to me, and more important to the subsequent flame front and combustion.

Also important as someone just pointed out is the cetane value of the fuel, which we know with SVO is out of spec for most (probably all) diesel engines (45 min. is the general rule of thumb). As a diesel mechanic, the way that I've dealt with these two issues is a simple solution that isn't backed by research, but is backed by countless hours of field/shop testing with hundreds of conversions over the last 9-years: add between 10-20% biodiesel to each tank of SVO. This not only has a thinning effect on the SVO but also provides a significant cetane boost to the mixture since biodiesel has a higher cetane rating than D2 as a general rule. I suppose in some way this leans on ACREVO a bit in the premise they put forward that some percentage of ethanol? (20% IIRC) blended with SVO will give it the same viscosity as diesel fuel at 80*C. It's been awhile since I read that study so my numbers and even thinning agent might be a bit off.

Now how does a mixture of 80% SVO and 20% biodiesel heated to 80*C at the time of injection perform in modern diesel engines, like a TDI? Very well I'd say, and to my trained mechanic's ear it sounds to me like it should, whereas with straight SVO it only sometimes does. Is this a cetane deficit, or a viscosity deficit? I don't know, but I do know that by adding biodiesel you kill two birds with one stone and no doubt make your engine/fuel injection system happier for it.

Every conversion we've ever done over the past 9-yrs has left our shop with this blend in the SVO tank along with my recommendation to the customer that they should always try to keep 10-20% biod in the tank.

As far as the efficacy of SVO temps in excess of say 90*C, one thing to note is that although the viscosity may approach that of diesel fuel, and combustion MAY be better, diesel injection pumps do not like to be heated as a rule, and to be heated over 200*F may lead to premature failure of the IP (and by premature I mean maybe failure after 100k miles instead of 300k or something along those lines). Diesel technology engineers have spent untold hours trying to keep internal IP temps low, and now we come along and introduce significant heat into the IP even at the 80*C level.

What I'm getting at with all this is that it's not a simple black or white issue. Higher temps. maybe good in some ways, but deleterious in others. Running with a chronic cetane # deficit (even with an obtuse timing correction) may be an even bigger issue in the long run, (and how that works in concert with injection temperatures is anybody's guess) but in the end we need more peer-reviewed research on these matters so we can know with some certitude what the actual best case scenario is for heated SVO burning in modern diesel engines.

And I think it goes without saying that we need unbiased researchers to be the PIs on the studies so I think the Linscott Institute for the Heated Advancement of Veggie Oil Combustion (LIHAVOC) is off the table.

justin

quote:

Originally posted by danalinscott:

I hate to be too cynical...but I wager that as soon as they have that capability they will do an abrupt "about face" on this issue.

So Dana, Now that you have seen the light and so emphatically believe in these Higher temps, are you going to be setting up a system for your fleet conversion clients that will operate at 250F or are you going to be happy with the status Quo and keep doing whatever it is you do now?

Good discussion of this subject here:
http://www.frybrid.com/forum/s...?p=106237#post106237

quote:

Originally posted by Edward Beggs:
80C is 176F.
90C is 194F.

And is that pre-injection or post injection Ed?
I assumed that it was post injection since nothing Plantdrive offers appears to be capable of achieving pre-injection VO temps that high.

quote:

diesel injection pumps do not like to be heated as a rule, and to be heated over 200*F may lead to premature failure of the IP

We certainly agree on that Justin. Which is why heat over 150F should only be added to VO AFTER it has pssed through the IP IMO.

quote:

What about cetane as an important characteristic of fuel

Cetane would appear to be taken into consideration in the Acrevo study.
When the combustion characteristics are the same as diesel due to lowered viscosity cetane rating would appear to be moot. I suspect this is why the temps quoted by the Acrevo study for this are higher than those indicated by the chart I produced.

quote:

Now that you have seen the light and so emphatically believe in these Higher temps, are you going to be setting up a system for your fleet conversion clients that will operate at 250F

My fleet clients have been using conversions that boost pre injector VO temps to over 220F. It is my hope that continued improvements of VO conversion technology will allow pre-injection temps of 250F+ to be acheived within the near future.

quote:

Good discussion of this subject here:
http://www.frybrid.com/forum/s...?p=106237#post106237

quote:

CG: I would be interested in ANY supporting research he or anyone has supporting an optimum temp of 230F or any other figure.

All Chris has do is ask...where it is possible for me to reply.
I cancelled my account at the FB forum when I was informed that someone was attempting to hack into it and so can no longer post there.

DEUTZ is the oldest and one of the world's largest independent manufacturers of diesel engines in the world.

Also, Deutz was the manufacturer of the older type direct injection engine used as part of the ACREVO study (but not for the parts where direct observation of atomization was done, as I have pointed out).

I had mentioned earlier that as the world moves use of newer diesel engines with higher injection pressures and computer control of multiple injection events, there is less and less relevance of the ACREVO study and less need for the very high temperature vegetable oil preheating being proposed in that study and in this thread.

Last year, Deutz, a company with vast engineering resources, and most certainly aware of the ACREVO study, done years ago, and the most active so far in moving forward with biodiesel and SVO, introduced a factory-equipped, fully warranted, commonrail direct injection engine, with their own patented controller.

The switchover temperature to SVO for the Deutz 2-tank factory equipped, factory-warranty, computer controlled direct injection engine is 60-65C engine temp.

The fuel preheat temperature is also 60-65C *for this engine with this controller*.

The vegetable oil preheat temperature is considerably lower than that used by most of the main aftermarket conversion companies; and far lower than what is proposed by the original poster as an across-the-board "optimum".

It is also far lower than what the ACREVO study authors proposed many years ago for their across-the-board statement:

"it may be recommended, for any attempt of using VO in an engine, to use the rape seed oil at relatively high temperature, of order 100-130 °C".

That recommendation dates from 1998, when the authors were not privy to the knowledge and experience gained by the simple fact of tens of thousands of long-term, successful, real-world conversions of a range of diesel engines; most of which have been operating with vegetable oil preheat temperatures in the 70-90 C range; some of which have had temperatures higher than that at idle and low engine loads.

thank you Ed ... is there a web site link this info is on?
omar
www.omarsales.com

http://www.deutz-fahr.com/GERM...VERVIEW&idproduct=57

http://www.deutz-fahr.com/GERM...ENGINES&idproduct=57

Fuels allowed for DEUTZ engines including rape seed oil
Deutz Technical Bulletin

! WATCH Appendix 1 / 16 !

http://www.deutz.nl/technicalcircularfuels.pdf


BMW Fan

This message has been edited. Last edited by: BMW Fan,

Hi Omar, it might be, but that's not how I obtained the information.

quote:

I had mentioned earlier that as the world moves use of newer diesel engines with higher injection pressures and computer control of multiple injection events, there is less and less relevance of the ACREVO study and less need for the very high temperature vegetable oil preheating being proposed in that study and in this thread.

Which you originally stated was backed by formal research...but are unable to provide ANY.

Look .. I understand it being your opinion.
And I can resepct it at that level.

But when you say that there is formal research which back that opinion and then cannot produce it it makes it impossible to respect that position as anything BUT your opinion.

To continue to say things like

quote:

That recommendation dates from 1998, when the authors were not privy to the knowledge and experience gained by the simple fact of tens of thousands of long-term, successful, real-world conversions of a range of diesel engines;

Ed..do YOU have some access to a study of "tens of thousands" of such success storys? Or are you just "assuming" that everyone that converts to VO and does not report later that there were serious problems constitutes a "long term success" story?

I realize that vendors want potential customers to believe that the problems with VO conversion have all been discovered and solved. But the fact is that while we have a MUCH better idea of what we are doing than 10 or 15 years ago most conversion are still an "experiment in progress". As a kit vendor it is pretty clear that all kit vendors have a vested financial interest in promoting that position.

But I think only the most trusting will be willing to ignore the existing science that exists based solely on any vendors opinion. According to other kit vendors a pre-injection VO temp of 70C or even 50C is sufficient. They appear to rely upon the same "tens of thousands of long term successful conversions" assumption to support their opinions just as you do. Since they appear to use the same basis for their opinions why are they not just as correct as you are? What made you choose a higher target VO temp than THEY did?


You appear to have the second highest pre-injection target temp for VO in the industry...so let's for the sake of argument accept your opinion that VO only need be heated to 80-90C prior to reaching the injectors. How exactly do you propose accomplishing that?

We have seen that Deutz uses 60-65C as the switchover and fuel preheat temperature.

Here is the summary of another study, this time from Austria, a three year study on a tractor engine, similar in size and type to the ACREVO study's engine. (In this case, an 80HP direct injection Perkins, which most of us that are experienced in conversions would consider a more challenging conversion than many of the indirect injection engines that have been converted in the last decade)

Study is from agricultural college in Austria, completed earlier this year.



Note: Engine type: 4 cylinder Perkins, Direct Injection.

“The series with vegetable oil-powered tractor is feasible

A modern series tractor, practical operation converted to vegetable oil, can be done!

A tractor was converted three years with 1,100 hours of operation with vegetable oil and continuously checked.


The technique

The main components of the conversion of the tractor with the engine are a vegetable oil heater to heat the vegetable oil to approximately 70 degrees Celsius just before the injection system. This is a 2-tank system.

Automatic switchover to vegetable oil once the engine is warmed up. (switchover temperature not specified).

Experience has shown that the warmup phase operating with diesel is, for winter, about 15 minutes in summer and only five to seven minutes.

There is an emergency stop button which can be used to over-ride the “turbo timer” used to automatically purge the vegetable oil when the engine is turned off.

"This technique is even for the common-rail technology and the pump-injector technology fit, "says the researcher.


In the three-year experimental period 5025 liters of vegetable oil and 605 liters of diesel were consumed.

Good quality cold pressed oil recommended.


For fuel-parts should be plastic or steel are used.

The preheating is a requirement for good exhaust emission values and a stable engine oil quality.


Therefore, the vegetable oil is preheated to 70 degrees Celsius.
The engine power is used in vegetable oil hardly noticeably lower fuel consumption by 3-5% higher.


The Vegetable oil has a high purity and dark and cold storage.


The emission measurements were in vegetable oil an approximately 20% lower particulate emissions than diesel.

• The engine testing was to use vegetable oil higher copper values.
• By replacing the copper heat exchangers in the copper value was back to normal.


Through the two-tank system, there was almost no record of vegetable oil in the engine oil.

Ed..
I notice that you chose to not even provide a citation for this study.
Just a claim it exists and your personal interpretation of it.

Why not provide the actual study so people can interpret it themselves?

I don't find it to increadible that an engine with a simple 70C two tank conversion can go for the equivalent of 55,000 miles on VO without mjor problems. I think we woudl BOTH be surprised however it it could continue to run such a conversion for the same number of hours/miles that it could on petrodiesel.

THAT is my goal.
Even with the most sophisticated conversion currently available it is not yet possible.
But opposing attempts to discuss what may be required to reach that goal by saying "my opinion is that what we do now is adequate" seems odd.

I also notice that you don't appear able to answer the simple questions I have put to you.
Calling your bluff..so to speak.

I think I have wasted enough time on this one, folks.

The information I have presented, which I believe provides a reasonable opposing view to the need for the higher temperatures Dana has proposed, can all be found with a bit of Googling and use of free, simple translation tools, and an email or two, if you are really interested.

Forums are a way to kill time in the winter, like researching and writing a thesis is a good thing to do in the winter, or doing cold weather testing is a good thing to do in the winter.

In the summer, there are many better things to do. Summer is too short, and life is too short, for much of this.


I'm going to go and enjoy the outdoors now and maybe go for a drive on vegetable oil on one of the many documented conversions I have actually done and have posted the pictures to prove.

Have a nice summer, Dana.