quote:

Originally posted by danalinscott:
The lower "cetane rating" attributed to VO does NOT appear to result in a corresponding ignition delay.

What are you basing that upon, got a source? There is a direct linear relationship between ignition delay and cetane well proven. Either is a measure of the other.

quote:

Here is a good post from a Cummins engineer detailing the specific changes I list with advanced or retarded timing:
http://dodgeram.org/tech/dsl/FAQ/timing.htm

Neither of those links lead to reports or info that verify what you claim they do.
Did you mistakenly provide different links than you intended?

OK here are some exact quotes from them since you aren't finding the info:
RETARDED TIMING ( - )
EXHAUST TEMP increases
CYLINDER PRESSURE decreases
BSFC (brake specific fuel consumption) increases
NOX (oxides of nitrogen) decreases
HYDROCARBONS (HC) increases
BLACK SMOKE: 1000RPM increases
BLACK SMOKE: RATED increases
WHITE SMOKE: < 1000RPM increases
WHITE SMOKE: > 1000RPM increases

Note that as CYLINDER PRESSURE decreases due to retarded timing, this will always result in a quieter knock! That also confirms lower mileage and higher emissions (except NOX) when retarded. Which claim I made isn't covered?

quote:

quote:

Heat has no effect on the CID.

Actually it does..and here is why.

It is undisputed that the lower the viscosity the finer the droplets of atomized VO is created by diesel injectors and the deeper the penetration of the spray pattern is.

Yes, shorter PID.

quote:

It is also undisputed that finer the droplets the greater the exposure of vo molecules to the heat and O2 present in the combustion chamber.

Again, shorter PID.

quote:

Also undisputed is that molecules of VO exposed to O2 and high heat rapidly undergo reactions that create peroxides.

The concentration of peroxides on the surface of the fine droplets of VO provide a AIT that is significnatly lower than VO has and peroxides combust at an extreme rate. As a result the AIT of VO is not what determines the ignition delay....the AIT of the peroxides coating the exterior of the VO droplets are. This may be why VO does not act as a low cetane fuel would be expected to when it is heated to temperatures where its viscosity is near that of diesel fuel.

You are very confused, read the NREL again. Quotes:
"Hydrocarbon combustion occurs only in the gas phase. (NO DROPLETS ANYMORE) Thus, for a liquid fuel, the first steps toward ignition involve transitioning from a liquid to a gas phase. The time required for this transition is the “physical delay”"

They nowhere state that "fine droplets of VO provide a AIT that is significnatly lower than VO", where did you get that? There is only one AIT for a fuel, that is when the peroxides combust.

This quote is about the CID:
"For ignition to occur, the fuel must be heated to a temperature sufficient for some of the weaker bonds to break and form radicals. The finite rate of these radical forming oxidation reactions is responsible for the chemical delay in compression ignition." (CID)
Since its a finite rate, it isn't changed by anything but the chemical property of the fuel, namely AIT which for VO is 690F, far higher and thus later than D2 at 410F.

quote:

[QUOTE] where is the detailed research backing your claim that you can fully compensate for the larger ignition delay (=lower cetane) of VO by increasing heat from 170F to 230F.?

quote:

I don't believe that I have made that claim.
Can you provide a quote where I did?

Sure, from page 2:

quote:

Originally posted by danalinscott:
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."

From page 2:

quote:

Originally posted by danalinscott:
Normally autoignition is applied to liquids and flash pointis applied to vapors.
Since it is the initial flame of the fuel VAPOR that provides the ignition source for the liquid fuel in a diesel combustion chamber I don't see how the auto ignition temp is applicable to this discussion.

quote:

Originally posted by danalinscott:
I don't see how the actual combustion of VO is effected by EITHER its' flash point or autoignition temperature.

From NREL:
"Fuels for compression ignition engines must ignite readily through autoignition alone."

quote:

Originally posted by danalinscott:
Even the authors don't conclude what you do from their research.

What, pray tell, does he suppose they concluded?

You don't appear to even be thoroughly reading the referrences YOU re presenting in this discussion..let alone the I am. Please reveiw the referrences thoroughly before responding.

quote:

quote:
Originally posted by danalinscott:
The lower "cetane rating" attributed to VO does NOT appear to result in a corresponding ignition delay.

"There is a direct linear relationship between ignition delay and cetane well proven. Either is a measure of the other."

From the NREL referrence link YOU provided several posts back.Compendium of Experimental Cetane Number Data

From that report:

quote:

Cetane number is a relative ranking of fuels based on the amount of time between fuel injection and ignition. The cetane number is typically measured either in a combustion bomb or in a single-cylinder research engine. This report includes cetane values from several different measurement techniques – each of which has associated uncertainties.

Also from that report:

quote:

If ignition does not occur promptly when the fuel is injected into the cylinder, unburned fuel will accumulate as the injection process proceeds. In addition, when ignition does occur, the rate of burning will be too rapid, resulting in engine knock that decreases efficiency while increasing engine noise and wear.

According to YOUR refference...a low cetane value results in MORE KNOCK..not less.

Also from that report:

quote:

Without adequate fuel ignition quality the engine will start with difficulty and run poorly.

Just as when (cold) VO with a very high viscosity is injected into a diesel engine.
But VO which is warmed does not exhibity this characterisitc.

quote:

molecules of VO exposed to O2 and high heat rapidly undergo reactions that create peroxides.

The concentration of peroxides on the surface of the fine droplets of VO provide a AIT that is significnatly lower than VO has and peroxides combust at an extreme rate. As a result the AIT of VO is not what determines the ignition delay....the AIT of the peroxides coating the exterior of the VO droplets are. This may be why VO does not act as a low cetane fuel would be expected to when it is heated to temperatures where its viscosity is near that of diesel fuel.

You are very confused, read the NREL again. Quotes:
"Hydrocarbon combustion occurs only in the gas phase. (NO DROPLETS ANYMORE) Thus, for a liquid fuel, the first steps toward ignition involve transitioning from a liquid to a gas phase. The time required for this transition is the “physical delay”"

I am not confused at all.

But you appear to be assuming that the entire fuel droplet transitions from a liquid to a vaopr instantaneously. This is not the case.
Let me explain in slightly more detail.


In order to understand what I was presenting (regarding peroxide formation) one needs to understand what is occurring during the combustion process in a bit more detail.

The largest part of ignition delay in a heavy fuel (such as VO) is the Physical Ignition Delay
(which you refer to as PID) This is where Visocosity has the largest effect since the lower the viscosity of VO the smaller the droplets of fuel are and the more they are mixed with the compressed heated air in the combustion chamber.

The PID of VO is the majority of the delay noted in cetane testing of VO since all fuels begin tested for cetane value are tested at a Standard Temp at which VO is much more viscous than it is at 230°F. When you eliminate the PID you eliminate most of the total ignition delay.

But there is also a reduction of the chemical delay when the viscosity of VO is reduced. This is because the droplets produced when VO is injected at a lowered viscosity are much more numerous and smaller. This exposes a much larger total surface area of the fuel charge injected to sufficient heat and O2. Exposure of VO to high heat and O2 causes a very rapid tranformation of the exposed Triglyceride molcules to peroxides. According to YOUR refference:

quote:

Peroxides are compounds with an R – O – O – R linkage. Most peroxides are extremely reactive and many are explosive. Peroxides have long been known to be effective additives for improving the cetane number of diesel fuels.

These tranformed triglyceride molecules/peroxides are already in the process of vaporization since they are on the outer perimeter of the droplets of VO. And being extremely reactive they have a very low autoignition temperature and so ignight almost instantaneously. The heat of this initial ignition (of the peroxides) ..since it is ocurring on the outer boundary of the VO droplets rapidly shrinking "exterior liquid/vapor boundary shell"..exposes the still liquid VO molecules to even more heat than was provided initially by the compression of the air in the chamber. This in turn speeds the vaporization of the droplet of VO.

The presence of combusting peroxides negates the need for this VO to reach its Auto Ignition Temperature before ignition is possible. Essentially once an ignition source is present in the droplet cloud the remaining VO molecules exposed to air ignite as they reach the flash point.


At this point the CID is negligable bing nearly identical to diesel fuel.

quote:

There is a direct linear relationship between ignition delay and cetane well proven. Either is a measure of the other.

quote:

This "linear relationship" is only applicable at the temperature that VO is tested for cetane value. Becasue VO is so viscous at the Standar Temperature at which cetane testign takes place the published cetane values of VO do not reflect ACTUAL ignition delay of VO that has a lower viscosity (inparted by heating). You are assumong that lowering the viscosity of VO has no effect on the cetane value. But this is an incorrect assumption.

You appear to acknowledge that you understand this when you state

quote:

There is only one AIT for a fuel, that is when the peroxides combust.

But you then go back to assuming that published cetane values for VO (at STP) reflect the actual cetane value of VO at a significantly higher temperature/lower viscosity.

quote:

Here is a good post from a Cummins engineer detailing the specific changes I list with advanced or retarded timing:
http://dodgeram.org/tech/dsl/FAQ/timing.htm

Neither of those links lead to reports or info that verify what you claim they do.
Did you mistakenly provide different links than you intended?


OK here are some exact quotes from them since you aren't finding the info:
RETARDED TIMING ( - )
EXHAUST TEMP increases
CYLINDER PRESSURE decreases
BSFC (brake specific fuel consumption) increases
NOX (oxides of nitrogen) decreases
HYDROCARBONS (HC) increases
BLACK SMOKE: 1000RPM increases
BLACK SMOKE: RATED increases
WHITE SMOKE: < 1000RPM increases
WHITE SMOKE: > 1000RPM increases

Note that as CYLINDER PRESSURE decreases due to retarded timing, this will always result in a quieter knock! That also confirms lower mileage and higher emissions (except NOX) when retarded.

quote:

Its well proven that longer ignition delay (=lower cetane) equals retarded timing, along with the effects I list. Apply simple logic, if the fuel is slower to ignite, the burn is later, which is the definition of retarding the timing.

quote:

Which claim I made isn't covered?

That VO at lower viscosity results in a LONGER ignition delay than diesel fuel at the similar viscosity.

quote:

as CYLINDER PRESSURE decreases due to retarded timing, this will always result in a quieter knock!

So will a fuel that has a higher cetane value. Or a fuel that has no ignition delay but has a slightly slower combustion rate. You are assuming there is ONLY one possible reason for this..and ignoring some of the information in your own referrences.

Which was:

quote:

Without adequate fuel ignition quality the engine will start with difficulty and run poorly.

quote:

quote:
[QUOTE] where is the detailed research backing your claim that you can fully compensate for the larger ignition delay (=lower cetane) of VO by increasing heat from 170F to 230F.?



quote:
I don't believe that I have made that claim.
Can you provide a quote where I did?

Sure, from page 2:

quote:
Originally posted by danalinscott:
If you can optimise VO fuel to match diesels vscosity 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."

And the refference to "you can fully compensate for the larger ignition delay (=lower cetane) of VO by increasing heat from 170F to 230F.?" It simply is no there. I have not claimed it. ANYWHERE.

Again..CHOOSING to ASSUME something is "implied" (which is actually NOT) is creating most of the disagreement on this subject. You are doing this not only with MY statements..but with the statments of the referrences you are providing..while seeming to ignore statements in YOUR OWN refferrences that disagree with your assumptions.

quote:

This quote is about the CID:
"For ignition to occur, the fuel must be heated to a temperature sufficient for some of the weaker bonds to break and form radicals. The finite rate of these radical forming oxidation reactions is responsible for the chemical delay in compression ignition."

But you assume it also says:

quote:

Since its a finite rate, it isn't changed by anything but the chemical property of the fuel, namely AIT which for VO is 690F, far higher and thus later than D2 at 410F.

I have explained why the AIT of VO is rendered irrelevent by the formation of peroxides. And you seem to acknoledge this when you say " There is only one AIT for a fuel, that is when the peroxides combust." But you are ASSUMING that the level of peroxide creation in all hydrocarbons is the same. This is clearly not correct.

Triglycerides contain O2 in thier molecular structure.
Diesel fuel does not.

This creates a significant difference in how they combust.
And in the speed and quantity of formation of free radicals.

quote:

The chart that Dana claims has not verifiable sources is more fully explained in the reference material section of the Frybrid forum, that is why that section and the two pages of research bibliography are also under the resources tab at the top of every page of the site.

No actual verification is provided.
Only the implication that the information has been verified by you or F.Gregg.

This is a very signficant difference.
Especially since the chart provided on the Frybrid website is demonstrably inaccurate by publicly available data.

quote:

You can refer to the research Mr. Gregg did while at Frybrid at the link below.

Actually one can only refer to SOME of the research he did while at Frybrid.
Some of the research he did (which appears to contradict the Frybrid chart) is not available there.

quote:

Since his point of argument, REDACTED, seems to be that VO needs to be hotter than “Frybrid theory” states, again he has not read much of the data provided freely on the Frybrid site

I have read all of it Chris.
But it is all presented in a very selective and incomplete manner seemingly designed to only prvide the portions of research that support the "frybrid theory".

quote:

I found that I could, using heated lines and multiple heat exchangers, produce fuel at 172F when the engine was at 180F.

Vo temps prior to the IP are not all that relevant..nor are injector spill/return temps.
Pre-IP temps are what is critical in such a discussion.

quote:

I believe the last time I provided this information his response was something like “Who would trust a paper from India”.

Then your memory is faulty on the matter.
I encourage you to find the actual statement rather than relyi on your own highly predjudiced memory.

What I recall is that in most cases you provide only a citation where you claim the data that backs your conclusions is located. In most cases this is not correct. And regardless the preponderance of available data indicates that your conclusions are either outdated or incorrect.

quote:

The fact is in 2003 he was sure that 170F was too high and that 104F would be better.

I think that there is a type there. I was sure..and remain sure that 170°F is a higher than desireable VO temp PRE-IP. We are discussing PRE-INJECTOR VO temp in this discusion.

The knowledge base has grown signifcantly since 2003..and as is so often the case what we understood was possible then has changed. At that time the technology did not exist to safely increase the PRE-INJECTOR temp of VO in conversions. Many (including myself) did not believe that post IP heating woudl ever be practical. This is now clearly not true. If you wish to continue to use the same data available to the VO community in 2003 you are welcome to. I prefer to stay current.

quote:

Even if viscosity were matched, the fuel would not burn the same, burn time, flame front formation, ignition delay etc would all still be diffferent

They can all be approximated very closely by reducing the viscosity of VO prior to injection. For example: one cannot change the available BTus in a gallon of VO (compared to dieselfuel) but one CAN compensate for it fairly easily.

I don't think any readers will confuse sarcasm with logic.
If you cannot post without the cheap shots and sarcasm I think what logic you present may experience a "validity reduction".

Your choice.

Would you like me to exlaborate on why the chart you posted on Frybrid is demonstrably and significantly incorrect?

Cetane number as a poor indicator of ignition delay of heated vegetable oil.

The protocol that defines cetane number requires that the fuel be heated between 65 and 90 F. We don't know the answer to the question of what the cetane number is of oil heated above this temperature, and indeed, as cetane number is currently defined, it is a nonsensical question. We do have very good indication that heated oil may have a shorter ignition delay than unheated petrodiesel from engine tests: Pugzhavidu, Bari, Yu, Nwafor, and Labeckas, all heated various oils above 70 C, and found shorter ignition delays than unheated petrodiesel ( full citations can be found here ). The most thorough treatment of the disconnect between cetane number and actual ignition properties for heated vegetable oil is Knothe's Biodiesel: The Use of Vegetable Oils and Their Derivatives as Alternative Diesel Fuels

Shorter ignition delay has opposite effect of advancing injection timing.

Combustion in a diesel engine can be characterized as having two periods. Premixed burning and diffusion limited burning. When diesel fuel is first introduced into the combustion chamber there is a period where the fuel evaporates and mixes with air before the fuel ignites. When the fuel does ignite, the premixed fuel and air will burn rapidly and create a short intense pressure increase. This is diesel knock. There are two ways to increase the amount of premixed fuel. First, advance the timing so that more fuel is introduced into the chamber before ignition temperatures are reached. Second, use a fuel with a longer ignition delay. This is covered in any good textbook on diesel engines. Personally, I like Richard Stone's Introduction to Internal Combustion Engines.

Auto-ignition and flash-points are different, and neither are very good indicators of the temperature of ignition in a diesel engine.

The flash point is the temperature that a material has to be heated in order to form a combustible mixture above the bulk material in the presence of source of ignition at atmospheric pressure. The autoignition temperature is the temperature that a material has to be heated in order to spontaneously combust, also at atmospheric pressure. I've only found one source of auto-ignition temperatures for vegetable oils: Wijayasinghe, Mahendra S., and Thomas B. Makey. 1997. Cooking Oil: A Home Fire Hazard in Alberta, Canada. Fire Technology 33, no. 2 (May 1): 140-166. doi:10.1023/A:1015395001403. They report auto-ignition temperatures of various cooking oils as between 300 and 450 C. Particular values can be found here

In a diesel engine, where the high pressure will bring fuel and Oxygen molecules closer together, the ignition temperatures will be lower.

Higher temperatures and effect on combustion
Increasing temperature will continue to reduce viscosity as well as ignition-delay, but as Curt pointed out at exponentially decreasing rates. In fact, vegetable oil will not have the maximum allowable viscosity of diesel fuel at 104 F until the oil is heated to around 280F. However, heating oil to these temperatures is not necessarily a net improvement, as the higher fuel temperatures come with trade-offs. Some that immediately come to mind are the energy cost of heating the oil to these temperatures, safety concerns, potential for vapor lock, thermal polymerization and loss of cooling of injectors. This last one strikes me as perhaps the most significant. Most diesel engines supply much more fuel to the injectors than the engine will burn in order to have the returning excess fuel cool the injectors. Injectors have very fine tolerances and at some point, high fuel temperatures will not provide enough cooling, and the injectors will not be able to function as designed.

I do think 70-80 C provides good combustion and is a temperature range which is easily reached. The papers I cited above support this. But I also think there are likely net benefits for heating above these temperatures. What I really don't know is at the point that marginal benefit is less than marginal cost. I don't think anyone does right now.

quote:

Originally posted by danalinscott:
What I recall is that in most cases you provide only a citation where you claim the data that backs your conclusions is located. In most cases this is not correct. And regardless the preponderance of available data indicates that your conclusions are either outdated or incorrect.

Is that not the point of citations, to show on what information ones conclution is based?
What conclutions do you feel are outdated or incorrect. If you are stating that the fuel temp conclution is incorrect please point out how and why you feel this to be true with citations or raw data from your "Research". I have done so with the cited study in the post which was deleted.

quote:

Originally posted by danalinscott:
They can all be approximated very closely by reducing the viscosity of VO prior to injection. For example: one cannot change the available BTus in a gallon of VO (compared to dieselfuel) but one CAN compensate for it fairly easily.

There are BTU's available from chicken as well but I do nto think heating it to 350F will allow it to be burned as completely as diesel fuel in a CI engine. I might suggest a marinade of olice oil, balsamic vinegar, lemon and rosemary, with some cherry wood however.

quote:

Originally posted by danalinscott:
Would you like me to exlaborate on why the chart you posted on Frybrid is demonstrably and significantly incorrect?

Which chart? The one you have choosen to post was created in 2003 using the smae method you have used here, looking at info available on the web. Later and more complete charts were compiled by Mr. Gregg and subsequently published on the Frybrid site.

quote:

This last one strikes me as perhaps the most significant. Most diesel engines supply much more fuel to the injectors than the engine will burn in order to have the returning excess fuel cool the injectors. Injectors have very fine tolerances and at some point, high fuel temperatures will not provide enough cooling, and the injectors will not be able to function as designed.

Can you provide verification of this claim.
Obviously some injectors may be less robust than others.
Can you list the less robust ones?

quote:

Which chart? The one you have choosen to post

Yes..the one posted prominently HERE on your site in the "theory" section. Just after the claim that:

quote:

when vegetable oil has been heated to 160F its viscosity is very close to that of petroleum diesel.

and refer to that chart.

quote:

Later and more complete charts were compiled by Mr. Gregg and subsequently published on the Frybrid site.

Can you post links to these.
They have not yet been linked to in this discussion.

Why would you post a chart which you KNOW to be inaccurrate so prominently on your website? And use it as the ONLY chart you provide to explain that

quote:

when vegetable oil has been heated to 160F its viscosity is very close to that of petroleum diesel.

Although that chart (which you now seem to be acknoledging is grossly inacurrate) DOES suuport that conclusion/claim a more accurate chart would not.

quote:

I have done so with the cited study in the post which was deleted.

A post of yours was deleted on this discussion?
Who deleted it?

quote:

They have deleted a reply I made and I had to open a new user account as mine has been deleted...

That must have been SOME reply!
Let me assure you that I had nothing to do with that.
Although I do not like your tactics wehn it comes to debating/discussing subejcts you do not agree with..I believe in much more gentle moderation techniques than banning individuals who cannot self moderate.

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

quote:

Originally posted by danalinscott:

quote:

This last one strikes me as perhaps the most significant. Most diesel engines supply much more fuel to the injectors than the engine will burn in order to have the returning excess fuel cool the injectors. Injectors have very fine tolerances and at some point, high fuel temperatures will not provide enough cooling, and the injectors will not be able to function as designed.

Can you provide verification of this claim.
oObviously some injectors may be less robust than others.
Can you list the less robust ones?

What claim? That injectors have fine tolerances? That many injectors are cooled by returning excess fuel? Or that hot fluids cannot cool as well as cooler fluids?

-Forest

quote:

What claim?

I thought it was clear.

quote:

at some point, high fuel temperatures will not provide enough cooling, and the injectors will not be able to function as designed

Can you provide verification of this claim?

Obviously some injectors may be less robust than others.
Can you list the less robust ones?

quote:

Originally posted by danalinscott:

quote:

What claim?

I thought it was clear.

quote:

at some point, high fuel temperatures will not provide enough cooling, and the injectors will not be able to function as designed

Can you provide verification of this claim?

Obviously some injectors may be less robust than others.
Can you list the less robust ones?

Can I provide verification that overheating due to inadequate cooling will cause the workings of finely mated mechanical parts to be out of spec? Sure, with this easy demonstration you can try at home. Simply go out to your vehicle, drain out all the coolant and go for a leisurely drive.

I am not claiming that if the injector depends upon being cooled by fuel that I know what temperature will start to cause problems. But I am certain that such a temperature exists.

Another worry is that all injectors, whether they return excess fuel or not, rely on the fuel that they spray to cool the injector tip. The main concern here is coking.

-Forest

quote:

Originally posted by danalinscott:
According to YOUR refference...a low cetane value results in MORE KNOCK..not less.

Yes timing that is far off either advanced or retarded causes more knock. The ideal is for VO to be timed to have the same knock as D2.

quote:

Originally posted by danalinscott:
The PID of VO is the majority of the delay noted in cetane testing of VO since all fuels begin tested for cetane value are tested at a Standard Temp at which VO is much more viscous than it is at 230°F. When you eliminate the PID you eliminate most of the total ignition delay.

PID isn't the majority of delay in any testing I have seen. Can you provide any research to show that?
You never eliminate the PID. Can you provide any research to show that?

quote:

Originally posted by danalinscott:
But there is also a reduction of the chemical delay when the viscosity of VO is reduced.

Can you provide any research to show that? The NREL report clearly shows viscosity as only affecting the PID.

quote:

At this point the CID is negligable bing nearly identical to diesel fuel.

Can you provide any research to show that? The NREL report states "For all but very heavy fuels, the physical delay is short compared to the chemical delay." The CID never becomes "negligable" even with D2, thats why they measure it so carefully and have laws mandating minimum cetane levels.

quote:

You are assumong that lowering the viscosity of VO has no effect on the cetane value.

No I said it has a minor effect, since it lowers the PID. I haven't seen any research showing whether that amount is +0.1 cetane or +1.0 cetane, it would be good to discover.

Where is the research backing your claim:

quote:

Originally posted by danalinscott:
If you can optimise VO fuel to match diesels vscosity 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."

The research you have posted shows that atomization is better with higher temps. You admitted earlier you have no studies of the mileage or power or emissions, which would be needed to say that "the engine is optimized for both fuels".

If we had studies showing an amount of improvement, then we could decide if for example a 1% improvement in mileage was worth the extra cost of equipment, and possible risk of damage to injectors or other expensive parts. Got any long (or short) term studies of electronic injected engines on 230F+ fuel?

quote:

I am not claiming that if the injector depends upon being cooled by fuel that I know what temperature will start to cause problems. But I am certain that such a temperature exists.

Another concern is that all injectors, whether they return excess fuel or not, rely on the fuel that they spray to cool the injector tip. The main concern here is coking.

So the answer to can you provide verification of your claim is NO.

In fact you seem to be saying that you do are not sure that the temperatures we are discussing here will be high enough to casue ANY problems for ANY injectors.

You originally seemed to imply that your statement "at some point, high fuel temperatures will not provide enough cooling, and the injectors will not be able to function as designed " was relevant to this discussion..but now you appear to be backing way from that implication.

Thankyou for clarifying that.

Do yo uhave any verifying info that backs up your claim

quote:

all injectors, whether they return excess fuel or not, rely on the fuel that they spray to cool the injector tip. The main concern here is coking

or is that too at a temperature much higher than is relevant to this discussion?

By the way..the link

quote:

( full citations can be found here ).

in your recent post leads not to the studies..only the names of studies. One would need access to the actual studies to use the citations to verify (or not) your claims.

Don't get me wrong. I appreciate that the post you provided that link in mostly agree with what I have been trying to explain to sunWizard. But although the "implication" you make when you do post such a link is "the verification is HERE clearly that link does not lead to verifying info.

As I said above, I think there is probably net benefit in heating oil above 70-80 C, but there are a number of potential costs that I am concerned about, of which loss of cooling of injectors is one.

It may not turn out to be a concern, but that's the point. I don't know now. If I am going to advocate that someone do strange things to their expensive engine, I should be careful and make the best effort to understand what the potential effects are. To that end it is important to not confuse not knowing whether something is a problem with knowing that it isn't.

As far as the references, I regret that academic publishing is organized the way that it is and that much of what is worth knowing is not freely available on the internet. However, that is the way it is, and to ignore information because you can't access it immediately is, I think, a mistake. You can get all references that I alluded to through your local library. If you need help using inter library loan, I'll be happy to walk you though it.

-Forest

quote:

I think there is probably net benefit in heating oil above 70-80 C, but there are a number of potential costs that I am concerned about, of which loss of cooling of injectors is one.

It may not turn out to be a concern

Thank you for re-phasing that more clearly.
I agree that there MAY be a such a concern.
But since there is no evidence that supports such a concern (or at least you apparrently have no source what so ever that indicates this is a valid concern) it is probably not applicable to this discussion.

quote:

As far as the references, I regret that academic publishing is organized the way that it is and that much of what is worth knowing is not freely available on the internet.

As am I.
However, providng a link that indicates that

quote:

"the verification of an otherwise unsubstantiated claim is HERE

when it is clearly not might mislead those who trust the implication it is.

Much more honest to say

quote:

You can get all references that I alluded to through your local library.

even if this is not within the ability of most.

It is too bad that you no longer have access to those resources yourself.
If you did you might be able to provide actual verification of your claims.

If one can set aside the V100/SVO 'tunnel vision', then it becomes obvious that many of the problems can be solved by adding ULSD and heating the fuel blend to 60°C - 70°C to ensure complete and clean combustion. I've been doing this for a few years, in a seasonally sub-zero climate, and the exhaust emissions tests show that no degradation of the engine or fuel system has occurred.

quote:

Originally posted by danalinscott:
Thank you for re-phasing that more clearly.
I agree that there MAY be a such a concern.
But since there is no evidence that supports such a concern (or at least you apparrently have no source what so ever that indicates this is a valid concern) it is probably not applicable to this discussion.

It may not be, but I don't know. It doesn't seem anyone knows.

quote:

Originally posted by danalinscott:
As am I.
However, providng a link that indicates that

quote:

"the verification of an otherwise unsubstantiated claim is HERE

when it is clearly not might mislead those who trust the implication it is.

Much more honest to say

quote:

You can get all references that I alluded to through your local library.

even if this is not within the ability of most.

This seems like a very discourteous representation. I did not say that the papers were at the link, I said that the full citations were. Citations which you will need when you go to your local library.

Why is it outside of most people's ability to got to their local library? Most of the people reading this forum are eligible for library cards and are not shut-ins.

quote:

Originally posted by john galt:
If one can set aside the V100/SVO 'tunnel vision', then it becomes obvious that many of the problems can be solved by adding ULSD and heating the fuel blend to 60°C - 70°C to ensure complete and clean combustion. I've been doing this for a few years, in a seasonally sub-zero climate, and the exhaust emissions tests show that no degradation of the engine or fuel system has occurred.

No only is that completely off topic John,
But...
Whever you have been asked to provide credible verification of THAT claim you have not been able to do so.

Are you able to do that yet?

Without that such claims are just unsubstantiated claims.

quote:

It doesn't seem anyone knows.

Actually there is pretty good evidence that it is NOT a concern at teh tempertures we are discussing. Although engine manufacturers publish warnings about excessive fuel temp for IPs I have been unable to find any about excessive temperatures for Injectors. Can you?

It seems to me from discussions with engineers that design diesel engines and components that similar to IPs as long as the fuel is not hotter than the component it still provides cooling. It is ONLY when this limit is exceeded that any of the engineers I have discussed this with exhibited any concern that the component might exceed its design limits.

quote:

This seems like a very discourteous characterization.

Perhaps it does.
The ambient level of civility on VO forums is much lower than on technical forums.
I too notice this as I tuen my attention several times daily from courteous/professionsl level discusions on techncal forusm to public forums such as this one.

I have learned over the years that one must have a very "thick hide" if one expects to post on these public forums.

quote:

Why is outside of most people's ability to got to their local library? Most of the people reading this forum are eligible for library cards and have modes of transportation.

I agree. But quite often local librarys do not provide access to the citations you provided.
Those that do have that access are often unwilling to help explain exactly what is required to gain access to technical journals archived articles, etc.

You and I may be able to access these articles, papers, etc..but the average reader of this forum will likely not be able to do so without investing many hours to understand the process of requesting such asccess..if they are able to do so at all.

it is unfortunate that all of the available research, data, and articles is not archived where access to it is more user friendly.

Perhaps you would be willing to lend your help to provide that access.
I am.

quote:

Originally posted by danalinscott:

Actually there is pretty good evidence that it is NOT a concern at teh tempertures we are discussing. Although engine manufacturers publish warnings about excessive fuel temp for IPs I have been unable to find any about excessive temperatures for Injectors. Can you?

It seems to me from discussions with engineers that design diesel engines and components that similar to IPs as long as the fuel is not hotter than the component it still provides cooling. It is ONLY when this limit is exceeded that any of the engineers I have discussed this with exhibited any concern that the component might exceed its design limits.

As noted above, absence of evidence is not evidence of absence, especially as we are talking about potentially heating the oil about 200 degrees F above typical diesel fuel temperatures.

The salient questions are what is the design temperature for the operating injectors and how much of the cooling depends upon the fuel versus conduction to the cylinder head. A well defined question we should be able to find answers to. That would be one concern down, quite a number left to go.

quote:

Originally posted by danalinscott:
I agree. But quite often local librarys do not provide access to the citations you provided.
Those that do have that access are often unwilling to help explain exactly what is required to gain access to technical journals archived articles, etc.

You and I may be able to access these articles, papers, etc..but the average reader of this forum will likely not be able to do so without investing many hours to understand the process of requesting such asccess..if they are able to do so at all.

it is unfortunate that all of the available research, data, and articles is not archived where access to it is more user friendly.

Perhaps you would be willing to lend your help to provide that access.
I am.

I have not found any public library system that does not offer inter-library loan service, and in my experience reference librarians are very happy to help their patrons. However, I allow that there is certain to be variation between libraries and library patrons, although I think that most people capable of successfully converting their vehicle to burn an alternative fuel will not find inter-library loan too challenging. It really is very simple, and should only take a few minutes.

In any case, I would be delighted to help anyone make better use of these bulwarks of democracy, and I'll post a notice to that effect by the link to my bibliography on my website.

-Forest