AbstractThe use of Diesel Particulate Filters (DPFs) as a means to meet ever more stringent worldwide Particulate Matter/ Particle Number (PM/ PN) emissions regulations is increasing. Fuel Borne Catalyst (FBC) technology has now been successfully used as an effective system for DPF regeneration in factory and service fill as well as retrofit applications for several years.

The use of such a technology dictates that it be stable in long term service and that it remains compatible with new and emerging diesel fuel grades. In order to ensure this, neat additive stability data have been generated in a very severe and highly transient temperature cycle and a large selection of current (Winter 2012) market fuels have been evaluated for stability with this FBC technology. Results indicate that FBC technology remains suitable.

The incidence of Internal Diesel Injector Deposits (IDIDs) is increasing, particularly for advanced FIE systems. These deposits generate a variety of field issues that can, in extreme cases, require the fitting of a new set of injectors. IDIDs have been studied using a representative bench engine test (sodium based deposits) and injector rig (ashless polymeric based deposits), whereby baseline deposit formation seen in the field has been shown to be reproducible. The results indicate that the effect of the FBC technology tested is neutral for sodium salt based IDIDs whilst benefits are observed for ashless polymeric IDIDs.

The rigorous FBC testing data reported confirm that appropriate FBC technology can continue to be reliably deployed in the field and, in the tests carried out, can also help prevent issues associated with ashless polymeric IDIDs.

IntroductionDiesel powered vehicles have improved remarkably over the years. Fuel consumption has been reduced dramatically whilst simultaneously lowering each of the noxious exhaust pollutants [1]. One of the main pollutants for any diesel engine is particulate matter. Particulate matter has two important dimensions, Particulate Mass (PM) and the number of particles present that form it - the Particle Number (PN). Both have now being tackled through the introduction of tighter emissions legislation limits [2] and as a result are forcing the introduction of wall flow Diesel Particulate Filters (DPFs). The filtration efficiency of such systems is very high and can deal with both forms of particulate, PM and PN, very effectively [1, 4]. For this reason, DPFs are now fitted as standard to new diesel passenger cars in the EU, US and Japan and have also been retrofitted to existing vehicles in other regions. This has also recently been extended to heavy duty type vehicles in these areas [4].

DPF technology is making a difference to emitted PM and PN levels from diesel vehicle exhausts and its use is increasing. However when deployed, the particulate material removed from the exhaust gas accumulates in the DPF. This leads to increased backpressure that raises fuel consumption and eventually leads to poor driveability. Therefore, this technology must be coupled with a method of eliminating the accumulated particulate matter - i.e. by oxidising the material that remains in the DPF. This process is known as regeneration. In order to do this, a variety of conditions need to occur from the correct exhaust temperature to the presence of catalysts to aid DPF regeneration (oxidation). So called DPF regeneration technologies need to be robust in their makeup to withstand a multitude of scenarios in the field. Today, catalysed DPF (cDPF) and Continuously Regenerating Trap (CRT®) technologies remain strong competitors to FBC additives for this purpose in developed regions, e.g., Europe.

Validation of Fuel Borne Catalyst Technology in Advanced Diesel Applications

2014-01-1401

Published 04/01/2014

Romaeo Dallanegra and Rinaldo CaprottiInfineum UK Ltd.

CITATION: Dallanegra, R. and Caprotti, R., "Validation of Fuel Borne Catalyst Technology in Advanced Diesel Applications," SAE Technical Paper 2014-01-1401, 2014, doi:10.4271/2014-01-1401.

Copyright © 2014 SAE International

“This paper is posted on the Infineum website with permission from SAE International. It may not be shared, downloaded, duplicated, or transmitted in any manner, or stored on any additional repositories or retrieval system without prior written permission from SAE.”  

Whilst each of the above aftertreatment technologies is able to work effectively with the current fuel qualities and drive cycles found in Europe, catalytic DPF regeneration solutions face different hurdles in the field in developing areas. In these regions, fuel quality is frequently not at the same level as that found in more developed areas. This often has a knock on effect on the implementation of mandatory nationwide DPF installation needed to meet the desire for stricter emissions legislation. An example of this is the diesel sulphur level in certain areas of China which can reach over one thousand ppm [5] with the diesel quality varying from region to region [6]. cDPF and CRT® technologies are unable to function above a sulphur level of ∼50 ppm as the precious group metals used favour the reaction of SO2 to SO3 instead of the reaction of NO to NO2 whereby the generated NO2 acts to oxidise the soot [7].This lack of regeneration capability and the formation of sulphate based PM can ultimately lead to total blockage and failure of the DPF. Additionally, the generation of sulphates is understood to influence overall particle formation at low temperature [7]. FBC technology is however known to be able to operate in fuels of varying sulphur content without detrimental effect to the operation of the catalyst and without formation of additional sulphates [8].

The focus of this paper is the use of an FBC technology as the chosen DPF regeneration strategy. Extensive work has been carried out in the past to identify the best FBC that combines both the ability to work effectively in oxidising PM and PN with safe deployment in the field in regions where fuels have high sulphur levels (in excess of 50 ppm and sometimes reaching over 1000 ppm) [9]. Bench engine testing has shown that this FBC technology has the ability to demonstrate successful operation under controlled conditions in the laboratory using a variety of fuel types, engine cycles and engine families. The latest technology is based on an iron core that has been demonstrated to be effectively trapped in the DPF [10], can provide excellent regeneration performance and is also NOx neutral (VERT® protocol [11]). Bench engine testing has also highlighted that although FBCs do generate some ash which remains in the DPF until cleaned, the quantity is minimal when considering both the contribution from the lube oil and the low treat rates of FBC additive which are currently required to effectively assist DPF regeneration [9].

The in-service use of FBC additives as part of an active DPF regeneration mechanism has been known for over 10 years. [12]. Prevalently to the data reported, the FBC technology described in this body of work, referred to in the text as FBC technology A, has shown proven performance in the field having been deployed in factory and service fill in the LD Passenger Car market by a large European OEM since 2009 without any reported issues. This is significant evidence that FBC technology is sufficiently robust to different engine drive cycles and field conditions and enables the complete aftertreatment system to meet Euro5/6 emission standards.

The data and discussion in this paper focuses on the severe no-harms protocol that an FBC technology must withstand for successful field deployment that include: (1) fuel stability data

using 2012 type diesel fuels and (2) further data on how to counteract injector deposits in conjunction with the tested FBC technology. The data presented indicate that the FBC additive tested is stable, with the FBC technology compatible with current diesel fuels and well suited for applications in new modern vehicles. Therefore this validates the continued applicability of suitable FBC technologies in advanced diesel applications found in the market today.

FBC Additive Severe No-Harms TestingAn important consideration for any vehicle technology is the discussion of the possible harms. No-harms testing is critical to show that the FBC additive does not have a negative effect on the diesel engine and vehicle components already present and also to prove the durability of the technology for the lifetime of the vehicle in which it is present.

Naturally the conditions employed in any such no-harms testing protocol should go further and be significantly more severe than those likely to be found in the field to cover any possible field operations and driving cycles. Reported first is the latest and perhaps severest no-harms test conducted; temperature cycling additive stability.

Neat Additive StabilityStatic temperature stability of the neat FBC additive at constant temperature is a simple but effective means of understanding additive stability over a desired time period. That said, such a test is not particularly representative of conditions in the field whereby the temperatures that the FBC additive is exposed to change constantly over time depending on the season and the location of the additive vs. the engine. Therefore, the temperature cycling stability test reported here attempts to further progress towards “real-life” by subjecting the FBC additive to changing air temperature conditions at the extremes of hot and cold that it would likely experience over time stored in a vehicle.

In the test procedure enacted, 900 mL of neat FBC additive (comprising FBC technology A) in a sealed glass container is placed in a specially designed rig which follows a temperature program cycling between −20°C and +90°C for a total of 9 months. The cycle repeats several times per day, ramping to temperature very quickly and holding for a period of time; it is in this respect that the test ages the additive. Frequently exposing the FBC additive to these temperature gradients and extremes aims to mimic > 10 years in-service stability of the additive in just 9 months. Rapidly alternating the temperature from very low to very high quickly generates particles with increased thermal energy which have a greater tendency to collide and as a result are more likely to form aggregates which would appear as sediment. Low temperatures enhance any insolubility based effects. Therefore, performing this operation continuously over a short time frame severely stresses the additive above and beyond what would be expected in the field.

Neat additive stability is assessed in several ways. First, a visual inspection of the level of sediment is conducted by carefully inverting the sample bottle at the end of the test. The picture in Figure 1 is an example and shows that only a trace quantity of sediment is found at the bottom of the flask at the end of the experiment. In addition, aliquots of sample are regularly analysed for their iron concentration and kinematic viscosity (KV) from both the top and bottom of the sealed container during the 9 month experiment. As can be seen from the graph in Figure 1, within the precision of the analytical tests, the iron concentration and KV remain constant over 9 months, indicating little change in the composition of the additive in this timeframe. Together these data indicate that the FBC additive used passes the test and is able to withstand challenging and changing temperature conditions. Furthermore, as FBC technology A has no issues in the field, this validates the cycle as a tool which can be used in advance to confirm that FBC additive stability can be maintained in service over long periods of time.

Figure 1. Top - Inverted sample flask after 9 months of the temperature cycling experiment. Bottom - Temperature Cycling Rig iron concentration and Kinematic Viscosity (KV) at 40°C data over the 9 months of the experiment.

Fuel Stability TestingStability in fuel is key for an FBC based additive. Improved fuel economy and advances in engine technologies mean that fuels are being stored and lasting longer in the vehicle before being

used. In an ideal scenario an FBC additive would add to the stability of the fuel; however, as a minimum it should be free of harms. To investigate the diesel fuel stability of FBC technology A, 19 diesel fuel samples were taken from 13 European countries for analysis (please see Appendix for full specification data). The selected fuels were a mixture between standard and premium grades containing FAME and different levels of diesel detergent sampled during the Winter season (2011/2012). Diesel additive concentrations peak during this period in order to prevent fuel-vehicle operability problems associated with cold temperatures. Using Winter diesel fuels thus helps maintain the utmost stability test severity. Each fuel was doped with FBC technology A at a treat rate of 8 ppm iron concentration which is in excess of that required for the latest engine technologies. The diesel samples were then monitored for iron concentration, filterability and RANCIMAT oxidation stability.

Iron ConcentrationThe iron concentration of each diesel fuel was analysed at weekly intervals from both the top and bottom of a vessel containing 800 g of diesel at ambient temperature over a 1 month period. The test duration is representative of a typical lifetime of the FBC additive in a vehicle fuel tank assuming that additive dosing takes place only on fuel tank refill. Sampling both at the top and bottom acts as a secondary check for the formation of sediment which would be characterised by a concentration gradient over time (an increase in iron concentration at the bottom vs. the top). Of the 19 samples, all showed a constant iron concentration over 4 weeks between the top and bottom of the samples and over time within the precision of the test method.

FilterabilityFilterability was conducted using the IP-387 test protocol (similar to ASTM D2068) which is an extreme no-harms filterability test designed to protect engine filters over a significant timeframe and is used in the fuels industry (e.g. EU and Korea). 300 mL of diesel is passed through a filter recording the pressure over a period of 15 minutes to yield a final pressure and a Filter Blocking Tendency Index (FBTI) value. EN590 does not stipulate a maximum value for FBTI, however, other diesel specifications have set a limit at 2.0 [13]. The test boundary limit set here was to a maximum pressure of 30 kPa after 15 minutes (FBTI = 1.04). As can be seen in Figure 2, 18 out of 19 fuels doped with FBC technology A at 8 ppm iron treat rate at ambient temperature were under this limit. The only sample which was significantly higher than this was a Spanish fuel which contained 3 times the maximum concentration of FAME as per EN590. In a control test the Spanish diesel fuel in the absence of FBC technology was found to have a worse FBTI and thus we rationalise that the FBC is not a contributing factor to this result (Figure 2).

Figure 2. IP-387 filterability test data.

RANCIMAT Oxidation StabilityThe Modified EN15751 RANCIMAT test is an oxidation stability test performed at 110°C which analyses the formation of volatile organic acids in diesel fuel by monitoring the conductivity over time. Organic acids result from a degradation reaction of FAME with oxygen upon heating. The time taken for these acids to reach the control chamber and cause a rapid increase in conductivity in the control sample is called the induction time. The EN590 diesel fuel specification states a pass limit of a minimum of a 20 hour induction period. In this study, samples were tested for a maximum induction time of 40 hours (double the requirement) after which the test was terminated.

Interestingly, it can be seen from the data that ∼21% of the non-FBC treated diesel fuels tested failed to reach the target of 20 hours when initially sampled (Table 1, Figure 3), rising to 32% of fuels after 9 months left to stand in a sealed container. The average value for the non-FBC treated diesel is also reduced by ∼2 hours over the same period and conditions. Of the 19 diesels, the FBC doped fuels gave a pass in 89% of cases whereby the non-FBC treated fuel originally met the specification at 9 months. The average induction time for the FBC doped diesel fuels was only 3 hours less than the non-FBC treated diesel samples at 9 months. Considering the reported reproducibility of the test method [14] and the observed changes in the non-FBC treated diesel samples alone over 9 months, the addition of FBC technology A, even at the elevated treat rate used, continues to permit diesel fuels formulated to meet the EN590 specification to have a RANCIMAT value of ≥ 20 hours.

In a follow up study currently underway plans are to understand the complexities of fuel and FBC stability in diesel fuel grades which one might expect to become more mainstream heading towards 2020 and beyond, e.g., HVO and GtL. These data will be the subject of a future communication.

Table 1. Modified EN15751 RANCIMAT oxidation stability of 19 European diesel fuels; baseline and doped with FBC.

Figure 3. Graph highlighting the range of induction times for the 19 diesel fuels tested with and without the addition of FBC technology. Diamonds at 40 hours are weighted to represent the number of samples reaching ≥ 40 hours; black dots indicate the average induction period.

Internal Diesel Injector DepositsReports of diesel engine injector deposits date back to when the compression ignition engine was first introduced. In recent years, their complexity has increased significantly as a result of

the new injector environment that increases the stress on the fuel and, at the same time, has reduced clearances that amplify any deposit related issue. The CEC F-098-08 PSA DW10 engine test has become the industry preferred protocol for the formation of deposits inside the spray-holes of common rail equipped engines [15, 16, 17, 18]. Spray-hole deposits lead to engine power loss and were the main focus for the industry between 2005 and 2010. Five years ago, a new type of injector deposit started to emerge with issues now beginning to arise in the field. Known in the industry as Internal Diesel Injector Deposits (IDIDs) these deposits occur on components located inside the injector. There are two main types of IDID; those that are based on sodium salts and those that have an ashless polymeric nature and are typically associated with the presence of a PIBSI type detergent in the fuel [19]. Due to the perceived threat that IDIDs can pose, a variety of industry activities have begun aimed at understanding this new phenomenon. Two examples are a CEN Injector Deposit Task Force currently working under the direction of ACEA and FIE OEMs and a CRC working group in the US. Although there has been some progress in this area, no industry recognised protocols currently exist. For this reason, experimental testing has been carried out using procedures either developed in-house or that have been validated by some of the main interested parties in this field. These protocols have then been used to understand the impact that the FBC technology reported in this paper has on IDIDs. Given the nature of the two different types of IDIDs currently found in the field, the work carried out has focused on each one separately.

Sodium Salt Based IDIDsThe first set of experiments focused on the understanding and the reproduction of IDIDs that are characterised by the presence of a metal salt (usually a sodium carboxylate) and whether FBC technology A can contribute to their formation. In order to study sodium carboxylate formation, the same engine (a PSA DW10B), cycle and set-up as per the analysis of the spray-hole deposits mentioned above was used [18]. To measure the presence of any IDIDs, thermocouples were located in the exhaust manifold to measure the exhaust temperatures from each cylinder (Figure 4). The rationale here is from several tests which have previously demonstrated that changes in exhaust temperature versus baseline are a good indicator for the presence of IDIDs [20]. A variety of additional measurements were also carried out for each test. These included: the engine power loss and exhaust temperature profile during the test cycle, the dismantling of the injectors at the end of test and checking for ease of opening (using a subjective rating from “normal” to “stuck”), assessing the severity of visual deposits (using a subjective rating ranging from “none” to “high”) and photographing all components. These additional tests aimed to further understand the impact and nature of the deposits and make sure that no false positive or negative conclusions were recorded from one standalone result.

Figure 4. Photo showing thermocouple positioning in the exhaust manifold.

The diesel fuel tested was treated with a source of sodium (sodium hydroxide) and kept moving in the storage vessel so as to ensure that there was continuous contact between the sodium source and the fuel. This practice, again, has been used in the industry [20, 21]. An acid (Dodecenyl Succinic Acid, DDSA) was also added to ensure that sodium could be absorbed into the fuel. The resulting salt has poor solubility and a similar composition to the sodium based IDIDs seen in the field. Figure 5 describes the set-up where the fuel was continuously mixed in a stainless steel environment.

Figure 5. Schematic detailing the sodium IDID testing set-up.

Figure 6 shows a typical example where deposits are seen on the surface of the injectors and on the fuel filter. The injector components were confirmed to have a sodium salt deposit by SEM-EDX analysis. In addition, the high level of sodium based IDIDs present on the fuel filter were close to impacting engine operations. The graph in Figure 7 shows the way that this deposit impacts exhaust temperature. The exhaust temperature was measured during the re-starting phase of the CEC F-098-08 test protocol (this phase occurs four times during the test). Each cylinder was monitored by two thermocouples resulting in the eight different temperature profiles shown on the graph. The profiles seen after the first 8 hours are as expected when there are no IDIDs, with only little variation in the exhaust temperatures. However, the gradual formation of substantial deposits changes the exhaust temperatures dramatically. This is evidenced at the end of the data collection (during the fourth 8 hour block) where the graph shows significant differences across the recorded exhaust temperatures versus the results during the first 8 hours.

Figure 6. Example of deposit formation on the injector (top) and fuel filter (bottom).

Figure 7. Representative example of test data output; red line = speed, all other colours = exhaust temperature in the exhaust manifold (2 thermocouples per cylinder).

Results of the Sodium Salt Based IDID TestingThe testing carried out with FBC technology A was aimed at understanding whether this technology has any impact on sodium based IDIDs as the FBC itself does not have the ability to form such deposits. Therefore, the baseline selected was that of a fuel that was treated with a sodium source so as to generate extensive IDIDs. The FBC treat rate used was 40 ppm iron (which is in the order of 10 times the treat rate for vehicles meeting Euro 5 legislation) so as to simulate severe conditions. The summary of the results from this testing are shown in Table 2. The diesel fuel used for both tests was the same reference fuel as that used in the CEC spray-hole coking test programme. This fuel was run with a maximum theoretical value of 10 ppm sodium in fuel, again at the top end of the level of contaminant used in the industry. As the sodium salt is not fully stable in fuel, its concentration was measured several times during the test run. Analysing the fuel from the return line ensured that that an accurate understanding of the sodium concentration seen by the injector was obtained. The recorded range of the sodium concentrations is the same for both test runs; hence the two tests compared here have the same severity.

Deposit formation is however sometimes insufficient to cause a change in the exhaust profile when the engine is restarted after the shut-down phase. Nevertheless, evidence for deposit formation in these two tests was clearly established by the injectors being difficult to disassemble at the end of test. The subjective rating of the IDIDs (always carried out by the same person to limit variability) shows the same result. These data therefore confirm that the FBC technology tested, even at high sodium contaminant concentration, is neutral towards this new field issue that has surfaced in the last few years, particularly for the latest engine technologies. Table 2 also lists the data obtained from the fuel filter where insoluble deposits were also captured.

Table 2. Conditions and data obtained from the sodium deposit testing programme for base fuel + DDSA and base fuel + DDSA + FBC additive.

In summary, these data indicate that FBC Technology A, even at a very high treat rate, is neutral towards sodium based IDIDs. The level of deposit obtained upon completion of the

test is also unaffected confirming that this FBC technology has no negative or positive impact on the rate of formation of such deposits.

Although not specifically relevant to IDIDs, when running this test the sodium contaminated fuel was also observed to generate spray-hole deposits. These deposits are likely based on a sodium salt as with the IDIDs. This level of deposit generated an engine power loss of ∼ 12%. Running the CEC reference fuel as previously used in the spray-hole deposit programme (which is without sodium or any other contaminant) in the same test gives an engine power loss of < 1 to 2 %. This indicates the detrimental effect of sodium on these deposits. Adding FBC technology A to the sodium contaminated fuel provided some control in this area as was indicated by a reduced engine power loss of ∼ 7%. FBC technology A therefore appears to have a degree of control on spray-hole type deposits. Moreover, as the test conditions used were severe e.g. containing high levels of sodium contaminants (leading to a high rate of deposit formation), it is possible that during normal engine operations FBC technology A could control the sodium based spray-hole deposits.

Ashless Polymeric IDIDsDespite originally being more concerned with sodium based IDIDs, in the last two years the industry focus has shifted to deposits that are defined as “ashless polymeric”. These are described and well characterised in references [19] and [22]. Reference 23 specifically mentions two PIBSI based detergents that have been assessed in field, injector rig and laboratory tests. One of these PIBSIs, a non-commercial sample that contains over 70% of the mono-reacted species and closely represents the type of detergent present in the market, was found to be critical in all tests performed. The internal components of the injectors also showed deposits when the fuel was treated with a typical fatty acid based lubricity improver. Therefore, to understand whether FBC Technology A could have an impact on the rate of formation of ashless polymeric deposits, the same additive combination and treat rate were used as per the sodium IDID testing.

PIBSI is a generic chemistry that has been used as a diesel detergent since the mid 1980's. The components are: PIB (poly-isobutylene), SA (maleic or succinic anhydride) and a PAM (polyamine) that when reacted produce a succinic imide. A variety of variables need to be taken into account when further describing this molecule; the polymeric backbone Mn and Mw distribution, the type of PIB used (usually the one for diesel detergents is known as highly reactive PIB) and the type of polyamine used. The two main products that form part of a commercial PIBSI are mono and di-reacted moieties. In essence PIB-SA-PAM and PIB-SA-PAM-SA-PIB. Typical PIBSIs used in the market have a PIB Mw of approximately 1000 and contain a high level of mono-reacted PIBSI molecules (PIB-SA-PAM). Commercial PIBSIs also typically contain a large proportion of the mono-reacted species as identified by a large peak in the low Mw region of the GPC trace of these materials [23]. The reason for this is that the mono-

reacted material has greater detergency performance and can therefore be used at much lower treat rates to achieve the same level of injector deposit control.

The approach used for this testing procedure was to select a market representative diesel detergent as the reference material. In the industry, some companies have used a narrow cut low Mw PIBSI in order to conduct this type of testing [20]. However, this approach was not followed in this study because the aim was to reproduce conditions as close as possible to what is seen in the market. Moreover, it was felt that we would be unable to routinely obtain a low Mw sample. This is due to the difficulty of defining a ‘low Mw polymer cut’ as the polymer composition at the low Mw end is likely to be variable from batch to batch as it is not a key process control parameter. Moreover, each PIBSI batch would also be likely to have different ‘reactivity’ as defined by the level of bis-maleation; again another non-key manufacturing parameter for this type of material.

Although conscious of limiting the number of potential variables, it was unfortunately not possible to run the exact same test conditions as found in reference 23. The chosen approach was to use another injector rig setup that had been demonstrated to generate IDIDs and, significantly, to reproduce real life IDID issues (Figure 8) [24, 25]. References 25 and 26 support the findings from reference 23 that quotes: “…analysis of many deposits shows evidence of PIBSI DCA. It is suspected that these polymeric lacquers occur following extended operation at high temperatures.”, thus validating the strategy used. Interestingly, the authors of 24 and 25 also note the same deposits seen in the injector rig when running the same fuels in a bench engine test that used cyclic conditions; a four cylinder Euro 4 engine, alternating between low and high load over the duration of 100 hours.

Figure 8. Schematic showing the rig layout used for the ashless polymeric IDID testing.

The simulated operating test conditions used here follow the thermal soak-back to the injector that occurs following severe engine operation as summarised in reference 25. With this test, as there are no fired engine conditions, it is possible to

continuously create a soak back environment by combining high fuel rail pressures and temperatures with a low injected volume. Therefore, this injector rig test is a good tool to condense a lifetime of occasional soak-back operation. In addition, it allows the generation of a level of deposit that can impact injector operations in a relatively short space of time using a small amount of fuel. In order to link the data to the more advanced fuel injection systems where this type of deposit is predominantly seen, the test runs at a rail pressure of 160 MPa. This pressure is typically reached in recent common rail applications. Testing uses one injector with the injection cycle producing only low fuelling rates which are similar to those seen in vehicles at idle. This has the added advantage of reducing the amount of fuel required for this test; usually four litres are enough. The test duration selected is the same as suggested in reference 25; 7.5 hours.

Results of the Ashless Polymeric IDID TestingThe baseline set-up used for the generation of ashless polymeric based IDIDs used the contaminants deployed in reference 22, and the test that was described in reference 25. Naturally, the first question to answer was whether combining these two approaches would generate IDIDs. The ability to run in a rig permitted carrying out multiple tests. As a result, the quality of more than one fuel was assessed: a fuel containing 10% fatty acid methyl ester and a B0 diesel fuel (run twice) to ensure that the data were repeatable. Each fuel contained the critical PIBSI described above at a treat rate of 1000 ppm and a fatty acid at a treat rate of 1000 ppm. The results showed the formation of high levels of internal injector deposits as shown by the photos in Figure 9 Test A (B0 diesel) and Appendix B Test C (B10 diesel). Moreover, the internal plunger from Test A was so stuck in the injector casing that it was impossible to remove by hand. Although plunger removal was possible, it required a machine that had to apply > 900 Nm before it was eventually removed.

The same tests were then repeated with the same fuels but this time containing FBC Technology A, again at a treat rate 10 times what is typically used in the field for advanced Euro 5 vehicles. Upon test completion, the internal injector components were found to have a significantly reduced level of deposit. This level was sufficiently low so as to permit the removal of the internal plunger without any effort; just like a new unused injector. Visually it was sometimes impossible to see any deposit (Figure 9 Test B (B0 diesel) and Appendix B Test D (B10 diesel)).

Unlike for the sodium based IDIDs where FBC Technology A is found to be neutral, in the case of ashless polymeric IDIDs the same FBC technology is observed to have a positive effect on both controlling and avoiding these deposits even under the severe test cycle and contaminant treat rates used.

Figure 9. Disassembled injectors from the ashless polymeric IDID testing. Test A column = baseline B0 diesel components (left); Test B column = B0 diesel + FBC additive components (right). Plunger as removed by hand from Test B (bottom).

Summary/ConclusionsDPFs are an effective and now commonly adopted means to control PM and PN to meet worldwide emissions legislation. Efficient regeneration of particulate matter collected by DPFs is crucial to their ability to function. With the variable fuel quality present in certain markets and the focus on also limiting NOx, there remains a challenge to implement DPFs as part of a suitable aftertreatment technology.

Consideration of the potential problems in the field led to the further evaluation of FBC technology A. The results reported here have highlighted that the FBC additive tested is stable even under extreme temperature conditions over extended time periods and that FBC technology A continues to be compatible with current market fuels, even those containing bio-components. This FBC technology has also been shown to be neutral towards the sodium based IDIDs discussed, whilst beneficial in controlling ashless polymeric based IDIDs that are considered to be the most critical in the market. A degree of control for sodium generated spray-hole deposits has also been reported. Deployment of this FBC technology in the LD or HD sector as factory fill or in the retrofit market therefore continues to be a viable option for DPF regeneration, particularly in markets that have variable and high level of sulphur in diesel.

References1. Johnson, T., “Vehicular Emissions in Review,” SAE Int. J.

Engines 5(2):216-234, 2012, doi:10.4271/2012-01-0368.2. Regulation (EC) No 715/2007 of the European Parliament

and of the Council of 20th June 2007 “on type approval of motor vehicles with respect to emission from light passenger and commercial vehicles (Euro 5 and Euro 6) and on access to vehicle repair and maintenance information” Official Journal of the European Union OJ L171/1.

3. Zhong, D., He, S., Tandon, P., Moreno, M. et al., “Measurement and Prediction of Filtration Efficiency Evolution of Soot Loaded Diesel Particulate Filters,” SAE Technical Paper 2012-01-0363, 2012, doi:10.4271/2012-01-0363.

4. Bunting, A., “China looks to fuel-borne DPF catalysts,” Automotive World: May 2013.

5. Internal Infineum Diesel Fuel Survey, 2011/2012.6. Bao, X., “The Status of Diesel Vehicle (Machine) Emission

Standard and the Development Trend in China”, China International Diesel Engine Summit 2013, Beijing, China, December 5-6, 2013.

7. Mayer, A., Czerwinski, J., Bonsack, P., Karvonen, L. et al., “DPF Systems for High Sulfur Fuels,” SAE Technical Paper 2011-01-0605, 2011, doi:10.4271/2011-01-0605.

8. Richards, P., “DPF Technology for Older Vehicles and High Sulphur Fuel,” SAE Technical Paper 2005-26-020, 2005, doi:10.4271/2005-26-020.

9. Caprotti, R., Field, I., Michelin, J., Schuerholz, S. et al., “Development of a Novel DPF Additive,” SAE Technical Paper 2003-01-3165, 2003, doi:10.4271/2003-01-3165.

10. Mayer, A., Ulrich, A., Czerwinski, J., Matter, U. et al., “Retention of Fuel Borne Catalyst Particles by Diesel Particle Filter Systems,” SAE Technical Paper 2003-01-0287, 2003, doi:10.4271/2003-01-0287.

11. Mayer, A.C.R., “VERT- Verminderung der Emissionen von Real Diesel-motoren im Tunnelbau Ein Verbuntprojekt von SUVA, AUVA, TBG, und BAFU,” TTM, 2000.

12. Salvat, O., Marez, P., and Belot, G., “Passenger Car Serial Application of a Particulate Filter System on a Common Rail Direct Injection Diesel Engine,” SAE Technical Paper 2000-01-0473, 2000, doi:10.4271/2000-01-0473.

13. Australian National Fuel Standard (Automotive Diesel) Determination 2001.

14. Ullmann, J., and Straub, G., “Oxidation Stability - Scope and Limitations of Modified RANCIMAT method EN15751 and Future Alternatives” presented at The Energy Institute Biofuels Conference, Windsor, UK, 2008.

15. Caprotti, R., Bhatti, N., and Balfour, G., “Deposit Control in Modern Diesel Fuel Injection Systems,” SAE Int. J. Fuels Lubr. 3(2):901-915, 2010, doi:10.4271/2010-01-2250.

16. Caprotti, R., Breakspear, A., Graupner, O., and Klaua, T., “Detergency Requirements of Future Diesel Injection Systems,” SAE Technical Paper 2005-01-3901, 2005, doi:10.4271/2005-01-3901.

17. Leedham, A., Caprotti, R., Graupner, O., and Klaua, T., “Impact of Fuel Additives on Diesel Injector Deposits,” SAE Technical Paper 2004-01-2935, 2004, doi:10.4271/2004-01-2935.

18. Graupner, O., Klaua, T., Caprotti, R., Breakspear, A. et al., “Injector Deposit Test for Modern Diesel Engines,” presented at the TAE Symposium, Stuttgart, Germany, 2005.

19. Ulmann, J., Geduldig, M., Stutzenberger, H., Caprotti, R. et al., “Effects of Fuel Impurities and Additive Interactions on the Formation of Internal Diesel Injector Deposits,” presented at the TAE 7th International Colloquium Fuels, Esslingen, 2009.

20. Schwab, S., Bennett, J., Dell, S., Galante-Fox, J. et al., “Internal Injector Deposits in High-Pressure Common Rail Diesel Engines,” SAE Int. J. Fuels Lubr. 3(2):865-878, 2010, doi:10.4271/2010-01-2242.

21. Westbrook, S.R., “Analysis of Some Unusual Diesel fuel Contaminants”, 9th International Filtration Conference, Paper IFC09-015, 2008.

22. Ulmann, J., and Stutzenberger, H., “Internal Diesel Injector Deposit Formation - Reproduction in Laboratory, System Bench and Engine Tests,” TAE 9th International Colloquium Fuels, Esslingen, 2013.

23. Reid, J. and Barker, J., “Understanding Polyisobutylene Succinimides (PIBSI) and Internal Diesel Injector Deposits,” SAE Technical Paper 2013-01-2682, 2013, doi:10.4271/2013-01-2682.

24. Lacey, P., Gail, S., Kientz, J., Milovanovic, N. et al., “Internal Fuel Injector Deposits,” SAE Int. J. Fuels Lubr. 5(1):132-145, 2011, doi:10.4271/2011-01-1925.

25. Lacey, P., Gail, S., Kientz, J., Benoist, G. et al., “Fuel Quality and Diesel Injector Deposits,” SAE Int. J. Fuels Lubr. 5(3):1187-1198, 2012, doi:10.4271/2012-01-1693.

Contact InformationInfineum UK LTD.www.infineum.com

AcknowledgmentsThe authors would like to specifically thank Dr. Paul Lacey of Delphi Diesel Systems for the use of the rig and rig protocol to run the ashless polymeric IDID testing reported in this paper

Definitions/AbbreviationsACEA - European Automobile Manufacturers' Association

CEC - Co-ordinating European Council

CEN - European Committee for Standardisation

CRC - Coordinating Research Council

CRT® - Continuously Regenerating Trap

DCA - Deposit Control Additive

DDSA - Dodecenyl Succinic Acid

DPF - Diesel Particulate Filter

cDPF - Catalysed Diesel Particulate Filter

FAME - Fatty Acid Methyl Ester

FBC - Fuel Borne Catalyst

FBTI - Filter Blocking Tendency Index

FIE - Fuel Injector Equipment

HVO - Hydrotreated Vegetable Oil

GtL - Gas to Liquid

IDID - Internal Diesel Injector Deposit

KV - Kinematic Viscosity

Mn - Number average molecular weight

Mw - Weight average molecular weight

NOx - Mono-Nitrogen Oxides

PIBSI - Polyisobutylene succinimide

PM - Particulate Mass

PN - Particulate Number

SEM-EDX - Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy

VERT® - Verification of Emission Reduction Technologies

APPENDIX ATable A1. Specification data for the 19 diesel fuels reported in the fuel stability study.

APPENDIX B

Figure B1. Disassembled injectors from the ashless polymeric IDID testing. Test C column = baseline B10 diesel components (left); Test D column = B10 diesel + FBC additive components (right). Plunger as removed by hand from Test D (bottom).

The Engineering Meetings Board has approved this paper for publication. It has successfully completed SAE’s peer review process under the supervision of the session organizer. The process requires a minimum of three (3) reviews by industry experts.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE International.

Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE International. The author is solely responsible for the content of the paper.

ISSN 0148-7191

http://papers.sae.org/2014-01-1401