SCRF versus CSF - Are we on the bleeding edge?

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VeryDiscoSport
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SCRF versus CSF - Are we on the bleeding edge?

Post by VeryDiscoSport » Tue Nov 07, 2017 9:28 am

Up until 24th October 2017 the soot particulate filter had always been referred to on the forum as the "DPF". Then I received "the letter" from the Executive Board with this statement: "The SCRF (Selective catalytic reductant filter) component was inspected and soot was found on the rear face. This component contains the diesel particulate filter." Initially this statement made no sense to me, and subsequently I mis-identified the SCRF component as the DOC: viewtopic.php?f=8&t=5379&p=76180&hilit=SCRF#p76180

Since then every time I have searched the web for "SCRF" at least one of the results has it written SCRF® implying that these devices contain protected intellectual copyright material. Trying to get to the bottom of this, today I found a scientific paper called "A Study of the Soot Combustion Efficiency of an SCRF® Catalyst vs a CSF During Active Regeneration" by Lasitha Cumaranatunge et al. The abstract immediately caught my attention:

The soot combustion efficiency of a Pt-based catalyzed soot filter (CSF) was compared to a Cu-SCR catalyst-coated soot filter (SCRF® catalyst) under active regeneration conditions. The CSF was found to have a significantly higher soot combustion efficiency compared to the SCRF® catalyst under typical active regeneration conditions (550–600 °C). Despite the thermodynamic equilibrium limitation of the NO oxidation reaction at high temperatures and the relatively small quantity of NOx in diesel exhaust compared to O2, there is sufficient NO2 production capacity in a CSF where the impact of NO2 to the overall soot combustion efficiency under active regeneration conditions is significant. The differences between a standard porosity filter typically used for a CSF vs a high-porosity filter used for an SCRF® catalyst can only account for a minor portion of the difference in the soot combustion efficiency observed between the CSF and SCRF® catalyst. The fast consumption of the NO2 produced in situ in the CSF by soot may be driving the thermodynamic equilibrium of the NO oxidation reaction to continuously produce more NO2 for further soot combustion during active regeneration, resulting in a significant increase in the soot combustion efficiency in a CSF compared to an SCRF® catalyst or an uncoated filter.

If the JLR component referred to in the letter actually does employ SCRF® technology, this opens up a new avenue of possibilities regarding the root cause for the unfathomably poor performance of the DPF and (with the glass decidedly half-full, to coin a phrase) maybe it points to the possibility of an early hardware fix. Any ideas?
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Re: SCRF versus CSF - Are we on the bleeding edge?

Post by VeryDiscoSport » Tue Nov 07, 2017 10:17 am

I think SCRF® belongs to Johnson Matthey: http://ect.jmcatalysts.com/catalyst-tec ... crf-system
The SCRF® system integrates Selective Catalytic Reduction (SCR) with a soot filter – the next step for diesel NOx control.

The schematic below demonstrates how the SCRF® system for light duty diesel improves system compactness and is an example of how, over the European drive cycle, it warms up more quickly than an SCR downstream of a CSF (due to its closer proximity to the engine) enabling earlier NOx conversion.

The SCRF® system allows improved thermal management of the catalyst on the vehicle, is technically a very demanding system and may require additional SCR/ammonia slip catalyst (ASC) to maximise NOxconversion.
Looking promising....next question - Are JLR a customer of JM?

EDIT - Yes, very probably...
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Re: SCRF versus CSF - Are we on the bleeding edge?

Post by Dashnine » Tue Nov 07, 2017 11:08 am

So to summarize (and clear at least my head on this), I read that SCRF is poor compared to CSF in terms of soot burning performance. So any hardware fix is replacing the SCRF (as now fitted and mentioned in the letter) with separate CSF and a possible secondary system for NOx reduction by injection of AdBlue?
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Re: SCRF versus CSF - Are we on the bleeding edge?

Post by Barnsh » Tue Nov 07, 2017 11:11 am

Dashnine wrote:
Tue Nov 07, 2017 11:08 am
So to summarize (and clear at least my head on this), I read that SCRF is poor compared to CSF in terms of soot burning performance. So any hardware fix is replacing the SCRF (as now fitted and mentioned in the letter) with separate CSF and a possible secondary system for NOx reduction by injection of AdBlue?
Yep and a better DOC and we're done .
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Re: SCRF versus CSF - Are we on the bleeding edge?

Post by Chippy » Tue Nov 07, 2017 11:16 am

Barnsh wrote:
Tue Nov 07, 2017 11:11 am
Dashnine wrote:
Tue Nov 07, 2017 11:08 am
So to summarize (and clear at least my head on this), I read that SCRF is poor compared to CSF in terms of soot burning performance. So any hardware fix is replacing the SCRF (as now fitted and mentioned in the letter) with separate CSF and a possible secondary system for NOx reduction by injection of AdBlue?
Yep and a better DOC and we're done .
It all sounds rather straightforward in theory but getting there is a completely different matter. Hardware fixes are the most difficult to accommodate in any situation and the space restrictions in place here make it even more difficult (and costly).
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Re: SCRF versus CSF - Are we on the bleeding edge?

Post by VeryDiscoSport » Tue Nov 07, 2017 11:56 am

Dashnine wrote:
Tue Nov 07, 2017 11:08 am
So to summarize (and clear at least my head on this), I read that SCRF is poor compared to CSF in terms of soot burning performance. So any hardware fix is replacing the SCRF (as now fitted and mentioned in the letter) with separate CSF and a possible secondary system for NOx reduction by injection of AdBlue?
Not unlike the way it is explained here: https://www.youtube.com/watch?v=yzRR8BTVsyw

SCR-DEF.JPG

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Re: SCRF versus CSF - Are we on the bleeding edge?

Post by VeryDiscoSport » Tue Nov 07, 2017 12:07 pm

Oh brother! I just spotted a section of common DNA spliced into the advertising blurb from Johnson Matthey :
The schematic below demonstrates how the SCRF® system for light duty diesel improves system compactness and is an example of how, over the European drive cycle, it warms up more quickly than an SCR downstream of a CSF (due to its closer proximity to the engine) enabling earlier NOx conversion.
Maybe the "British driving style" isn't compatible with the "European drive cycle", it's 240 volts all over again.
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Re: SCRF versus CSF - Are we on the bleeding edge?

Post by Chippy » Tue Nov 07, 2017 12:24 pm

VeryDiscoSport wrote:
Tue Nov 07, 2017 12:07 pm
Oh brother! I just spotted a section of common DNA spliced into the advertising blurb from Johnson Matthey :
The schematic below demonstrates how the SCRF® system for light duty diesel improves system compactness and is an example of how, over the European drive cycle, it warms up more quickly than an SCR downstream of a CSF (due to its closer proximity to the engine) enabling earlier NOx conversion.
Maybe the "British driving style" isn't compatible with the "European drive cycle", it's 240 volts all over again.
And that from a British company ;)
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Re: SCRF versus CSF - Presentation

Post by VeryDiscoSport » Tue Nov 07, 2017 12:30 pm

Haven't gone through this yet but seems to bear the same title as the paper.
2016CLEERS_Cumaranatunge.pdf
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Re: SCRF versus CSF - Are we on the bleeding edge?

Post by Chippy » Tue Nov 07, 2017 12:52 pm

A bit more bedtime reading VDS. But interesting.

Just glancing through the first few pages I notice:

Page 3 - Key features of an SCRF® catalyst

Enables smaller overall system volume (First bullet point).

So have they chosen the SCRF because everything else available is bigger or for other reasons.

If they have then a "bigger" solution is a no go.

Or have I misunderstood something?
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