Cyclone filter for diesel particulates?
 

I've been thinking about this and i reckon there's merit in it. If the pressure drop across it was low it wouldn't load the engine too much and given a suitable way of dealing with particulate collection it may work well.
Ok, it would have to be periodically emptied but apart from that, it might just work. It would eliminate these silly DPF's i see giving trouble and costing lots of money people don't have!

Thoughts, calculations?

I'd love to see anything that is better (= less hassle) than today's DPF's. Periodical emptying shouldn't be a problem, as replacing oil, filters, etc., is standard practice which no-one questions.

I don't know exactly how small of particulates can be caught with a cyclone - the really small stuff (which I believe is the largest health concern) would require a very strong centrifugal force. But if a cyclone filter could be made with the same restriction as present DPF's, but without the extra fuel needed to burn out, then I think the car companies would already be all over it.

I've read a little about alternatives to PDF technology and it seems like there isn't a practical alternative right now. Hopefully in a few years we will come up with a better alternative to what we have now. I'd really like to be able to run alternative fuels thru the Jetta, but the built in restrictions have me kind of worried about it.

One of the most viable DPF alternatives is an electrostatic discharge grid. Any particulate that flows through the grid gets zapped like a bug in a bug zapper. The problem with it is the power requirements and potential noise.

I don't think any solution where you have to empty it will fly with government regulators. They want something that won't require human maintenance. Also since the diesel soot would be classified as a hazardous substance there would be costs dealing with it (even if you just burn the stuff to get rid of it).

Cyclone separators do work but less well in a moving environment as the movement upsets the flow path of the particulates being sorted.

In a previous life I was working in the mining industry (tin mining and extraction) and we had cyclones damn near every where in the production stream and one attempt was made to add them to shaker tables as a secondary step.

The shaker tables worked well and the cyclones worked well so long as both operated independently.
Bolt a cyclone to anything which moves and all you get is a mess.

At the moment as mentioned above DPF is the most viable way to achieve the required result and YES car makers know about cyclone filtration / separation too.

Peter.

If they were to use a separate, post cylinder injector, most DPF issues would be gone.

How so?

Rather off the original topic but it seems that using catalysts to 'hold-onto' spare O2 in the exhaust could have many uses in ensuring the cleanest emissions throughout the whole driving cycle.

I found a paper on: Reducibility of Catalyzed Cerium–Praseodymium Mixed Oxides
that claims:
"Quantitative results indicate that [Cerium–praseodymium mixed oxides] may be useful, in conjunction with hydrocarbon traps, for treating automotive cold-start emissions. "

I think they could also be useful in DPF burn off cycle for the same reasons.