Diesel Retrofit: Are DPFs Worth It?

Hello,

Please take a look at this.
http://www.dieselrussfilter.de/deutsch/index2.html
and write what you think about it.

Is there at least a theoretical possibility of upgrading older TDIs to achieve better emission classes, such that a retrofit might be worthwhile due to reduced taxes ?

Hello Ulf,

While I have to commend TwinTech for their initiative, as beautiful as the description is, the retrofit filter will not work.
Filters designed like those from TwinTech, which are constructed to prevent clogging, will allow soot to pass through under dynamic load conditions, and may even blow out accumulated soot. The catalytic coating is intended to reduce the combustion temperature, but it has the disadvantage that the catalyst and soot are not as well mixed as when an additive is added to the fuel. An oxidizer catalyst placed before the soot filter can be used for what is known as the CRT (Continuous Regeneration Trap) effect (soot combustion starting at approximately 230 °C). However, this only functions within limited operating ranges.

It's unlikely that such a product could be classified into a better emission class, otherwise TwinTech would have already done so. If it could, the filter would definitely be a huge success.
Even without electronic intervention, the NOx problem remains.
I also think that diesel soot is a major problem, especially with trucks.
However, I don't think retrofitting achieves much in passenger cars; we need proper, regulated solutions, which fortunately is what most manufacturers are now implementing.

Best regards,
Albrecht.

Hi,

Years ago, there was a particulate filter for a Mercedes diesel engine that completely retained the particles. As far as I know, it sometimes required a full-throttle run to burn off the particles, so that the back pressure didn't become too high.

Don't you think it's possible to build a real filter that completely retains the particles and, through the use of special coatings, enables after-combustion without additives? This should be technically possible without significantly increasing fuel consumption (->low back pressure) .

Well, the retrofit solution is commendable, but in my opinion, it won't achieve much. Most German diesel vehicles already meet Euro 4 standards without a filter, while the HDI models from France only meet the standard with this filter.
Certainly, there will eventually be a maintenance-free filter; the initial resistance to the introduction of the G-series was almost the same. Nowadays, these 'filters' are also maintenance-free. However, ash accumulation is a bigger problem. Over time, it reduces the filter's efficiency.

I find the approach of VW and Bosch, etc., which aims to prevent the formation of particulate matter in the first place through optimal combustion, to be much more elegant. This increases engine efficiency (which is actually reduced by the particulate filter), requires even less fuel, and results in cleaner exhaust emissions. That's why I prefer this solution.

Besides that... only 4% of particulate matter in Germany is produced by passenger cars, so a diesel engine that produces no particles will hardly have any impact.
So, my answer is: Green Commerce!

Hello Christian,

"Of course, that's possible! But not like the retrofit filter from TwinTech, but rather as a factory-installed option with a control system and silicon carbide or sintered metal filters."
The filter that Mercedes is now introducing (for the 220 CDI) is already very close to being optimal in almost every aspect (e.g., with a 99% efficiency rating).
However, it also has a higher fuel consumption, which I believe was 0.3 liters per 100 km in the EU consumption cycle.
It's like burning a brick under the car every 310 miles, completely uselessly.

Best regards,
Albrecht.

Good morning!

Here's another approach to reducing pollutant emissions (but it's probably only interesting for commercial vehicles due to the relatively complex system and costs).

http://www.spiegel.de/auto/aktuell/0,1518,269140,00.html
However, it remains a mystery to me how this solution is supposed to achieve fuel savings.

Greetings from Capernaum.

Hi! The urea catalytic converter can actually reduce the soot content within the engine, indirectly: Urea catalytic converter reduces NOx -> Exhaust Gas Recirculation (EGR) is eliminated -> less soot at partial load (because there is no EGR).

This could have a positive impact on urban traffic, as it is typically characterized by partial load conditions.

0.3L of extra fuel consumption for a particulate filter is quite a bit.