there are also parameters you can adjust in combinations which allow you to improve NOx, PM, and efficiency. In some cases injection pressure falls into this category (combined with timing and/or compression ratio).
oh yeah, now that I read above I see you already mentioned that... I don't think it's impossible that you could have an engine which would have lower NOx and higher efficiency if the fuel were distributed better. The paper does claim that the effect of the field is similar to higher injection pressure... perhaps the fuel spray is bad to begin with, and happens to get better with a bit of help?
For diesel fuel, the number of smaller droplets increased (some are smaller than five microns) when the fuel device was switched on. There was less of an effect with petrol.
Er, isn't the idea that petrol will vaporise and mix with air while diesels and heavier fuels are atomised?
Anyway, it seems the expert opinion is not that favourable either.
By the way: "Temple University has applied for a patent on Tao's work and has licensed the technology to California-based Save The World Air Inc."
Now there's a nice company name designed to play on the Californian conscience.
In certified laboratory testing, STWA’s technologies have reduced air pollution in combustion engines by as much as 98%, improved overall power by 19%, and enhanced fuel efficiency up to 33%
What looks good on the STWA web site is the link to RAND but if you follow through and read the RAND report on motorcycle trials etc it is less impressive reading.