The point at which SVO is actually hot enough to match diesel fuel at normal running temps appears to be in the range of 250F according to the chart I just produced using verifiable info on (ASTM)diesel fuel and SVO.

quote:

Kinematic viscosity of an oil is its resistance to flow at a specific temperature. The viscosity of a fuel decreases with increasing temperature. The viscosity of the fuel at the injectors has to be within the limits prescribed by the engine manufacturers. Incorrect viscosity at the injectors may lead to poor combustion, deposit formation and energy loss.

http://www.fammllc.com/famm/fuel_guide_to_quality.asp

quote:

The major difference in physical characteristics between canola and diesel is in the viscosity. Canola is more than 12 times as viscous as diesel at 20oC, and remains more than six times as viscous even after heating to 80oC.

http://www.eitg.co.nz/biofuels/biofuels.htm

quote:

Why are vegetable oils transesterified to produce biodiesel? This question will mainly be dealt
with in other parts of the course(s), but briefly, vegetable oil methyl esters have lower viscosities
(resistance to flow of a liquid) than the parent vegetable oils (think of honey or syrup, which
have high viscosities and flow with difficulty, vs. water or milk, which have low viscosities and
flow easily). Compared to the viscosities of the parent vegetable oils, the viscosities of vegetable
oil methyl esters are much closer to that of petrodiesel. High viscosity causes operational
problems in a diesel engine such as poor quality fuel injection and the formation of deposits.

http://www.biodiesel.org/resou.../20040701-gen369.pdf

So even B100 (100% biodiesel) is deemed to be too viscous (by engine manufacturers) for optimum combustion when injected at the same temp as petrodiesel.
http://www.enginemanufacturers...brary/upload/924.pdf

quote:

Kinematic viscosity affects injector lubrication and fuel atomization.
Biodiesel fuel blends generally have improved lubricity; however, their higher viscosity levels
tend to form larger droplets on injection which, can cause poor combustion

Certainly WVO is not exempt from the viscosity problems associated with higher than diesel fuel viscosity.

These are the links to the referrence material used to produce the chart which clearly shows how hot svo/wvo must be warmed to before it is equal to the viscosity of diesel fuel.
Please feel free to check its' accuracy.

http://www.biomatnet.org/secure/Fair/F484.htm

http://www.canola-council.org/...6/chemical1-6_1.html

http://www.schroederindustries...iscosity%20chart.pdf

http://www.engineeringtoolbox....viscosity-d_397.html

http://www.nrel.gov/docs/fy03osti/31460.pdf


http://www.brevardbiodiesel.org/viscosity.html


http://www.biomatnet.org/secure/Fair/S484.htm

http://www.microhydraulics.com...0654b3a?OpenDocument




Since diesel fuel also burns more efficiently as its' viscosity drops and the pre-injector temp of diesel fuel tends to run in the 30C to 50C (85F to 120F) at full operating temp the temperature at which SVO viscosity is comparable to THAT viscosity is around 110C (230F).

It appears that although VO from dfferent sources has significant variation in viscosity at temperatures under 80C (175F) at temps above that they have the same viscosity for all practical purposes. High fat WVO has a slightly higher comparative viscosity until the around 105C (220F)but follows the same relative viscosity as SVO at temps over that.

Based on my own research (comparing unburned fuel levels of WVO at various pre-injector temps to diesel fuel in the same engines) this chart which providea visual comparison of existing independent data, and the conclusions of the "Acrevo study" it appears that the target temp for SVO/SVO (pre-injector) is 120C - 130C (230F-250F).

The green horizontal line in the chart below highlights this MINIMUM temp/viscosity target for VO.


Edit:
Additional info on diesel fuel viscosity:

quote:

Viscosity The viscosity is a measure of the resistance to flow of the fuel, and it will decrease as the fuel oil temperature increases. What this means is that a fluid with a high viscosity is heavier than a fluid with low viscosity. A high viscosity fuel may cause extreme pressures in the injection systems and will cause reduced atomization and vaporization of the fuel spray. The viscosity of diesel fuel must be low enough to flow freely at its lowest operational temperature, yet high enough to provide lubrication to the moving parts of the finely machined injectors. The fuel must also be sufficiently viscous so that leakage at the pump plungers and dribbling at the injectors will not occur. Viscosity also will determine the size of the fuel droplets, which, in turn, govern the atomization and penetration qualities of the fuel injector spray.

http://www.tpub.com/content/co...64/css/14264_160.htm

quote:

Fuel atomization is also affected by fuel viscosity. Diesel fuels with high viscosity tend to form larger droplets on injection which can cause poor combustion

http://tdiclub.com/articles/Diesel_Fuel_Guidlines/

quote:

Viscosity: A measure of a fluids resistance to flow.
In a diesel fuel viscosity affects the shape of the fuel spray characteristics.
With high viscosities the fuel jet tends to be a solid stream instead of a spray
of small droplets. As a result the fuel is not well distributed in the air required for burning.
This results in poor combustion, loss of power and fuel economy.

http://www.finalube.com/fina_c...heck_diesel_fuel.htm

quote:

High viscosity leads to poorer atomization of
the fuel spray and less accurate operation of
the fuel injectors.

http://www.ajes.in/PDFs/09-1/3...20Fuel%20(r-pdf).pdf

quote:

Research shows that vegetable oil
or greases used in CI engines at levels as low as 10% to 20%, can cause long-term engine
deposits, ring sticking, lube oil gelling, and other maintenance problems and can reduce
engine life. These problems are caused mostly by the greater viscosity, or thickness, of
the raw oils (around 40 mm2/s) compared to that of the diesel fuel for which the engines
and injectors were designed (between 1.3 and 4.1 mm2/s). To avoid viscosity-related
problems, vegetable oils and other feedstocks are converted into biodiesel. Through the
process of converting vegetable oil or greases to biodiesel, we reduce viscosity of the fuel
to values similar to conventional diesel fuel ( biodiesel values are typically between 4 and
5 mm2/s). The maximum viscosityis limited by the design of engine fuel injection systems. Higher viscosity fuels cancause poor fuel combustion that leads to deposit formation as well as higher incylinder penetration of the fuel spray which can result in elevated engine oil dilution with fuel.

http://www.mnsoy.com/documents...iodieselHandling.pdf

quote:

the researchers found that the spray pattern of vegetable
oil was nearly identical to petrodiesel when the viscosity of the oil was still
nearly double that of the conventional
fuel. Specifically, oil heated to
285° F with a viscosity of 4.1 centistokes
looked the same as the spray
pattern of unheated petrodiesel that
had a viscosity of 2.4 centistokes at
40° C

Edit:
With the help of Forest Gregg it was determined that a more accurate chart of the temp/viscosity looks like this chart:

A close up of the lower area of that chart:

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

Thanks for doing this work and posting the info, Dana. Some recently posted research also points out the importance of injection pressure (and injection timing) as an equally important part of getting the most complete combustion possible from VO in a diesel. Unfortunately for me, most of that info is in German, which I can't read. It would be interesting to see a graph that would correlate the effects of each of these elements. Sorry if this is a little OT.

I'd always wondered whether VO viscosity could ever match diesel. I had my suspicions given how Frybrid published a version of that chart with the bottom redacted.

Now, how does one get the VO that hot without affecting the normal diesel fuel functions?

I imagine 2 seoerate fuel systems with most of the heat on veg system, have then come together just before injection pump. Would this high a heat be derived from coolant and do engines run that hot for long?

quote:

Frybrid published a version of that chart with the bottom redacted.

To be clear..the chart/graph I created was based on the Frybrid chart FORMAT but is not based on the (incorrect) information provided by that chart. I expanded it to allow the complete curves to be shown out to the temps and viscosity I found data for.
AFAIK Frybrid did not "redact" anything from an existing chart.

quote:

Some recently posted research also points out the importance of injection pressure (and injection timing) as an equally important part of getting the most complete combustion possible from VO in a diesel.

If the temp of VO can be raised sufficiently those measures are not neccesary. I believe folks implement those measures in lieu of being able to sufficiently raise pre-injection temps of VO sufficiently in an attempt to adjust fo the slower combustion of less atomized fuel.

quote:

how does one get the VO that hot without affecting the normal diesel fuel functions?

Raise the temp of VO as high as practical prior to the IP using FPHE (usually around 150F-160F) and then using high efficiency Injector Line Heater and high temp insulation on the injector lines raise it as close to 250F as possible.

quote:

Would this high a heat be derived from coolant

No..under normal circumstancesmcoolant does not get hot enough and if it did it would be exceptionally difficult to apply that heat post-IP.

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

I have always found this paragraph interesting, from the ACREVO study:

"The overall combustion performance of the rapeseed oil are very satisfactory in comparison with the diesel fuel while the rapeseed oil produces almost 40 % less soot than diesel fuel. The different volatility of this fuel respect to the diesel fuel is responsible of the different behaviour of the sampled gas concentrations in the base of the flames while at the end of the flames, both attain almost the same values. It has been established that an addition of 9 % of ethyl alcohol (95 %) bring a great benefit regarding the pre-heating oil temperature. In fact, the presence of alcohol allows a reduction in the inlet oil temperature from 150 °C to 80 °C. Moreover, the combustion of the emulsion produces less soot and, at the exhaust, the amount is almost one half less than that produced by the combustion of rapeseed oil."

It seems that now that we live in an era where fuel grade ethanol is so much more available than a few years ago, it might be worthwhile experimenting with this blend...if you can get a 50% reduction in soot, at 80 degrees C, versus what is attainable at 150 deg. C for the 100% vegetable oil, that's worth trying. And it might be especially useful for WVO.

---

Note that some oils are much less oxidatively stable than what the ACREVO authors found to be the case for rapeseed (Canola) oil. This is important - before one starts heating used soy, etc. to 230F+, it will be a very good idea to find out what that is doing to the oil.

Soy is not the greatest for SVO (semi-drying oil) at the best of times. What happens to it, for example, if you start preheating to this level?

Also what other issues might be created by heating the oil to this level on a longer term basis?

Will it cause problems for injection pumps, seals, computers that make fuel injection calculations with fuel temp. as one parameter, etc.?

We made a Vegsensor available for the Vegtherm to address some of these concerns that people had - it was easy, without it, for the Vegtherm to get temperatures up into the range under discussion here, and I believe it was fine, especially a low engine loads, a good thing, but not everyone agreed, and so the Vegsensor keeps it south of 100C. Which, in the case of the VW TDI, for one, was necessary, to prevent them going into limp mode when the computer senses a fuel temp that is too high.(80-90C seems to be a good range for those)

So, I think that while the higher fuel temps are generally good, especially at idle and low engine loads, and especially in a direct injection engine, it is not *always* necessary, or perhaps even desirable, to try to achieve temps. above the usual 70-80C range that is cited other research than the ACREVO study.

What is clear from all this is what we have said for a long time - that coolant heating alone is not sufficient - many coolant-only SVO systems operate, sub-optimally, in the 50-60C range. I think that is not good for emissions or for the longer term health of the engine.

Coolant+electric works best to ensure adequate preheating of the fuel.

quote:

It seems that now that we live in an era where fuel grade ethanol is so much more available than a few years ago, it might be worthwhile experimenting with this blend...if you can get a 50% reduction in soot, at 80 degrees C, versus what is attainable at 150 deg. C for the 100% vegetable oil, that's worth trying. And it might be especially useful for WVO.

Unfortunately the emulsions of rapeseed oil and ethanol cited by the Acrevo study is very difficult to stabilize and prevent from absorbing moisture from the atmosphere that useing it is not now practical.

quote:

before one starts heating used soy, etc. to 230F+, it will be a very good idea to find out what that is doing to the oil.

Soy is not the greatest for SVO (semi-drying oil) at the best of times. What happens to it, for example, if you start preheating to this level?

About the same thing that happens when it is used in fryers. Certainly no one is suggesting that VO be heated to this level in the tank...where oxidaton problems woudl certainly eventually appear. But when heated to this temp just prior to injection there is simply not enough time or oxygen to cause oxidative reactions of any significance.

quote:

Also what other issues might be created by heating the oil to this level on a longer term basis?

Will it cause problems for injection pumps, seals, computers that make fuel injection calculations with fuel temp. as one parameter, etc.?

Certainly! If one attempts to heat VO to temps above 150F BEFORE the IP. But why would anyone attempt to do that?

quote:

We made a Vegsensor available for the Vegtherm to address some of these concerns that people had - it was easy, without it, for the Vegtherm to get temperatures up into the range under discussion here, and I believe it was fine, especially a low engine loads, a good thing, but not everyone agreed, and so the Vegsensor keeps it south of 100C

I was gratified when Plantdrive finally heeded my advce and began offering the Vegsensor. Unfortunately 100C is still too hot to avoid posible damage to IPs IMO.

quote:

So, I think that while the higher fuel temps are generally good, especially at idle and low engine loads, and especially in a direct injection engine, it is not *always* necessary, or perhaps even desirable, to try to achieve temps. above the usual 70-80C range that is cited other research than the ACREVO study.

Can you provide those citations Ed?
As it stands all the research I have done personally and all that I have seen done by others on VO combustion efficiency shows that a temp of 230F is about the lowest desireable VO temp for maximum fuel combustion/minimum carbon accretions.

Tessol NADI used a percentage of isopropyl alcohol in the mix, along with other cosolvents. It is possible to stabilize these mixtures. The patent on that one, for instance was issued for stability up to 12 months, I believe. That's a lot longer than the small operator needs. As for the hygroscopic nature of the mix, I think you'd have to analyze the resultant mixture and actually run it, with the oil coating all the internals, obviously, and see if you had any problems that way.

I'm in the middle of a real-world, actual conversion, of a JDM Toyota Hilux cabover 4x4 longbed (what a cool truck!) so I'll respond to your other items in more detail later.

Suffice to say the Vegtherm is well-proven, we don't have any issues with injection pumps,it actually has been shown to heat the oil significantly, and the "80C" is well-documented.

The Vegsensor, as I said, keeps temps south of 100C, more in the 70-90C range, and can be placed for higher or lower temperatures, as the user desires. It was developed in response to the need of keeping temps lower on the newer computer controlled engines, to keep them from going into limp mode, etc., not in response to your opinion, with all due respect.

What is done with return fuel, incidentally, if it is heated to 230F+?

If one loops it, it's going right back into the injection pump, so no difference heating with the Minnesota Fats ILH's or whatever or pre-FIP...and if you send it to the tank, well, you're soon going to have a tank of very hot oil, a la the FryBrid Over-Heater tank heater, and the issues that causes.

Keep in mind that the engine studied in ACREVO was a small-displacement 3 cylinder direct injection Deutz, mechanical injection. The results for that engine will not be the same for most other diesels. In actual fact, both smaller cylinder diameters and direct injection present issues for atomization that do not exist for other engines. You can have a larger cylinder diameter and have no need of such high temperatures, you can have different piston bowl shapes and not have such a need, you can have indirect injection, Pumpe-Duse, Commonrail, etc. and all have their own needs. I'd say this little Deutz, as much as like the ACREVO study, is atypical of the engines most are converting to SVO.

quote:

the "80C" is well-documented.

Saying so doesn't make it so Ed.
Please provide the referrences to that documentation or I don't think many will believe it is in fact "well documented".

quote:

What is done with return fuel, incidentally, if it is heated to 230F+? If one loops it, it's going right back into the injection pump.

quote:

and if you send it to the tank, well, you're soon going to have a tank of very hot oil,

It is either cooled and looped back to mix wth the cooler "fresh from the tank" VO or cooled and returned to the tank.
I prefer the first.

quote:

Keep in mind that the engine studied in ACREVO was a small-displacement 3 cylinder direct injection Deutz, mechanical injection. The results for that engine will not be the same for most other diesels. In actual fact, both smaller cylinder diameters and direct injection present issues for atomization that do not exist for other engines. You can have a larger cylinder diameter and have no need of such high temperatures,

This has not been my experience Ed.
I deal with very large engines and in fact they DO respond with more complete combustion as pre-injection VO temps approach 250F.

quote:

I'd say this little Deutz, as much as like the ACREVO study, is atypical of the engines most are converting to SVO.

As far as fuel atomization and combustion efficiency/carbon acretion I would have to disagree Ed.
But if you have any documentation to support the opposing position I would love to see it.

quote:

It was developed in response to the need of keeping temps lower on the newer computer controlled engines, to keep them from going into limp mode, etc., not in response to your opinion, with all due respect.

The timing was very "coincidental" then.
I debated the need for it (on the Frybrid forum) with Craig ( who said there was no need)...and explained not only WHY it should be added to the Vegtherm...but HOW to do it as well...and one month later it is available for sale.
Not a big issue anyway. Not worth debating why Plantdrive began to offer temp regulation for the VT..I am just glad it was finally offered.

I assume that when Plantdrive finally offers injector line heaters the offical line will be that I had nothing to do with THAT decision either. That's OK..I am used to it. It doesn't really matter WHO gets the "cedit" it only matters that VO conversion technology continue to improve.

quote:

Tessol NADI used a percentage of isopropyl alcohol in the mix, along with other cosolvents. It is possible to stabilize these mixtures.

The mixture needs to be constantly re-mixed in storage...and isopropyl Alcohol is significantly different than ethanol. If they could have gotten similar results with ethanol they would have patented THAT. They couldn't.

There is nothing new about the info in this thread. That Frybrid chart gets posted on this forum a few times per year. The Acrevo (Advanced Combustion Research for Energy from Vegetable Oils) studies are not new either.

quote:

Originally posted by hheynow:
There is nothing new about the info in this thread. That Frybrid chart gets posted on this forum a few times per year. The Acrevo (Advanced Combustion Research for Energy from Vegetable Oils) studies are not new either.

If you compare the Frybrid Chart to the data in the links I provided you will notice that it is significantly "off" not only on the SVO curve but on the diesel curve as well. The chart I provided is based on industry and govt info (which I have provided links to). I don't know what the Frybrid chart is based on.

I created the new chart because up till now there was not one available that could be proven to be accurate. THAT's what new.
Here's the Frybrid chart:

Here's the new one.


Here they are superimposed on each other:

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

Creating a chart from work done by other people is not research.
Doesn’t it come to mind that faults are extrapolated , too ???
That chart is not based on research done by the chart producer.

Standard for Diesel has changed so has for different veggie oils.
A chart done 1992 must be different from one done today.
Next , some studies are European , some N.A.
Even Canola oil differs from rapeseed used in Europe and then again differs from varieties used in the 1990’s.


BMW Fan

quote:

That chart is not based on research done by the chart producer.

Correct.
It is based on data available to anyone caring to expend the effort to gather it and apply it to a grid. It DOES however agree with the research I have done personally as well as the findings of other VO fuel researchers. I have provided the links to where the data came from so others can easily verify the charts accuracy.

quote:

Standard for Diesel has changed so has for different veggie oils.
A chart done 1992 must be different from one done today.

This chart is not based on "standards" but rather the physical properties of several VOs and ASTM diesel fuel. Those physical properties have not changed since 1992.

Very informative chart, thanks for compiling it. I assume the 'diesel' is summer grade D2. Once diesel fuel is heated to 40°C it's viscosity does not change much with increased temperature. A 50:50 mix of D2 and VO at 65°C is approximately the same viscosity as D2 at 0°C.

quote:

Originally posted by john galt:
Very informative. Once diesel fuel is heated to 40°C it's viscosity does not change much with increased temperature.

Yes, but its lubricity drops with heat.

quote:

Originally posted by hheynow:

quote:

Originally posted by john galt:
Very informative. Once diesel fuel is heated to 40°C it's viscosity does not change much with increased temperature.

Yes, but its lubricity drops with heat.

Not if VO or BD are mixed with the diesel.

quote:

Once diesel fuel is heated to 40°C it's viscosity does not change much with increased temperature.

That's just not born out by the facts John.

At 40C diesel fuel has a viscosity that is roughly double the viscosity of diesel fuel at 100C.

It depends on how one interprets the graph. When the temperature increases from 1°C to 4°C, the temperature will quadruple but the effect of the change isn't significant.

quote:

It depends on how one interprets the graph.

I am not interpreting the graph John..I am simply reporting the data.

quote:

When the temperature increases from 1°C to 4°C, the temperature will quadruple but the effect of the change isn't significant.

I have yet to see a scientific VO fuel study that has not considered that viscosity difference to be signficant. My own research regarding the completeness of VO combustion has clearly shown me that there is a very significant increase in VO combustion efficiency when the VO is warmed to 100C compared to 40C.

If you don't think that the lower viscosity experienced above 40C is significant I challenge you to find data or legitimate research that supports that theory.

Here is the best scientific study I have seen that compared D2 and VO at temps of 30C (86F), 75C (167F), and 135C (275F), see post#3:
http://www.frybrid.com/forum/showthread.php?t=3596

The results show very tiny (<2%) improvements in Fuel consumption, thermal efficiency, and smoke opacity when going from 167F to 275F. EGT and NOX emissions were worse at the higher temp.

The reason these charts are good is they are actually measuring engine performance parameters under the varying conditions. I haven't seen any other figures like these posted to support the claim that 230F+ is the "optimum". I don't think those tiny improvements justify the extra cost, complexity, and risk of other failures (such as damaging electronic injectors, or problems due to higher EGTs) related to the higher temps.

The conservative approach I follow says that since most VO users are operating just fine near 170F, that much more testing is needed before recommending people raise that to 230F and higher.