The soot buildup in the DPFs must be periodically removed in a passive or active way. If it is not removed according to the manufacturers’ recommendations it will plug and cause serious engine damage.

The most common passive regeneration devices burn off the soot at high temperatures during normal engine operation and are found mostly on vehicle engines that are normally operating at high RPM’s (i.e. long haul highway trucks).

Active regeneration devices are considered for engines that are in idle and/or low rpm’s for a considerable time during their operational lifetime (construction equipment, garbage hauling trucks). These types of DPF’s require that the engine be placed in a high rpm mode for a lengthy period of time (30 minutes or more) to attain temperatures sufficient to burn off the soot build-up. Obviously this creates an added expense not only in fuel and operator costs but also down time during the work day.

Passive devices are expensive but they have long lifetimes paralleling that of the engine itself and require little servicing if they are properly maintained.

The Active designs however are another story. Since they are constantly building up soot and require considerable operator scrutiny and maintenance, their lifetime can be much shorter and add considerable expense to any business using them.

Filter designers are constantly experimenting with ‘new’ designs and interior substrate materials to extend the time between required regeneration. Another alternative to improving the regeneration process may be the recently CARB-approved fuel additive, Viscon. Some of its customers are reporting positive effects (extended time between regenerations). This would be easy to explain, as Viscon (according to the CARB testing reports) decreases PM emissions by more than 25% by improving the fuel itself (making it a more uniformed blend). As it accomplishes that PRIOR to the combustion, it simply decreases the PM load received by the DPF and subsequently extends the operational time between required regeneration periods.

www.worktruckonline.com/Article/Print/Story/2008/01/What-Fleet-Managers-Should-Know-About-Diesel-Particulate-Filters.aspx

www.msha.gov/nioshmnmfilterselectionguide/mnm_dpf_explanations.pdf

Fuel additives can chemically provide some of this efficiency but the negative tradeoffs just aren’t acceptable in today’s world.

Cleaner Diesel Fuel Additive – How might this be done?

A review of the literature provides some clues.

A pure low molecular weight (1-2 million) hydrocarbon polymer, polyisobutylene, is currently used in many industrial processes to exert a viscoelastic effect where other hydrocarbons in the mix are made to relax and thus improve the outcome. The details have been extensively studied and this viscoelasctic effect on hydrocarbons has also been shown to improve their combustion in fuels.
The details have been reported and we can look at them in the next entry. For now… check this reference material on viscoelastic effects.

I checked out the literature reviewing the history of the development and it is lengthy and full of incredible designs that look as if the engineers were given a great deal of allowance for even the most far out possibilities. It seems that once into the challenge, it was realized that with so many variables to consider maybe we can simply roll the dice and perhaps discover one that is far better than all the rest.

Fuel and air mixing, pressures, temperatures and how they are timed to enter the combustion cylinders were just part of the problem. Even the cylinder walls and their geometries proved to be critical to the best designs and matching them all up was full of problems. Even those that reached the finals sometimes were scrapped simply because they could not meet the emission reductions required for the time period.

If you are interested in reading the details here are some of the most notable references:

• Spark Ignition Engine – HighBeam.com
• Internal Combustion Engine – ThunderPress.net
• Ignition System – Motorera.com

Over the years I have had lots of interactions with people who had a variety of backgrounds, some with quite a bit of knowledge on the subject and others with a limited experience. . In general, the subject is not an easy one to really be an expert in, due to the vast “confusion and noise” caused by various product manufacturers’ claims.

The most common questions and debate remain related to whether they are worth the investment and do they do what they were designed (and claim) to do?

Here are some of the questions I ask when determining the value and efficiency of an Additive:

• 1. How does it work?
• 2. Does it affect combustion physically or chemically?
• 3. Is it regulated by Federal or State agencies?
• 4. Is it officially verified by a State, or Federal agency?
• 5. Can it have a negative effect on the engine?

Knowing what questions to ask when considering a fuel additive purchase might be a good place to start since rising fuel costs are continuing to eat away at the bottom line and fuel additives should be one of the considerations to ease the pain a little.

But, like for so many people I have had conversations with this can be a very, very daunting challenge. It may seem that it is too hard to do an intelligent evaluation, but believe me, it isn’t!

Here are some of the more frequent statements made by the users of fuel additives I have talked to:

• “Yes, I have used them but I never ever will again!”
• “No, I gave up!”
• “Yes, I tried a couple but one really messed my engine up!”
• “Yes, I currently use one but I am not really sure if it is worth the $$.”
• “I thought I was pretty smart and started to evaluate which one to use……..what a brain tease that was!”

So it goes. Some confusion. Some satisfaction. The question is, was it really worth the $$? What do you think? Share your thoughts with us.

Diesel Fuel Additive – What Questions to Ask?
Remember that a list of questions is really important to help you focus on your real needs and get through the amount of “noise” related to diesel fuel additives in the market place.

1. What is it exactly that you would like to Accomplish?
• Are you seeking emissions reductions?
• Self imposed or regulatory mandate ones?
• Are fuel consumption reductions your goal?
• Are you looking to ‘clean up the engine’?

Hint: The fuel of today is usually full of additives already required in the refining process. So, if you have a suspect engine that needs a mechanics attention don’t waste the $$ just yet.

2. Do you have friends, business associates, neighbors, etc. who are currently using an Additive or who have used them before?

Hint: A trusted, verifiable reference is a big one. Remember to ask some specifics such as: “Have you confirmed the stated benefits post purchase?”

3. Does the Manufacturer list the Ingredients?
• Certain ingredients are more harmful than you may think
• Some others will improve your engine performance but increase the harmful emissions at the same time

4. How does the Fuel Additive work?
• Is it a physical interaction with the fuel or a chemical one?
• A chemical reaction with the fuel ingredients might produce harmful byproducts that have potential to harm the engine and they might end up as toxic air contaminants.

5. Are there any Test Results available?
• What should you look for?
• Strict State and Federal testing guidelines required to receive formal verification are often your best bet

Hint: Not all tests are created equal, or relevant to your situation. Frequently, there are just too many variables and not enough statistical value.

6. The Actual Product Evaluation.

Read more on this one in the following blog posts or check out our website for more information about Viscon fuel additive.

Now go ahead and tell me what your experiences may have been!