Document xj31wgLr2anvg7eeanJpZvKv6

I : . .V the car, Bone 75$ of the Fb consumed 1b emitted as particulate. Emissions tend to increase vith age. EmiBBionB of gross particulate matter are highest when the engine is cold. Particles can he expected to he larger at low exhaust gas velocity owing to enhanced opportunity for coagulation and wall loss, and indeed it appears (Ref. 36) that nitrate and sulfate particles are larger at lower road speed. It is presumably true that oil burners are smoke producers. Diesel particulate emissions rise very steeply when the engine load approaches its maximum rating. Various means of control for gross particulates have been tried. A system of fluted exhaust pipes (for cooling) followed by a mesh-filled box and a cyclone collector (DuPont, Ref. 28) reduced Fb emissions 10-fold. Other systems (Ref. 1*2) include thermal precipitation in a packed bed or acoustic coagulation in a fluidized bed, or (Ref. 32) a simple trap muffler. The con trol of blowby gets rid of much of the problem, 6ince the particulate emissions .in blowby are in quantities approaching the tailpipe emissions. Catalysts for the control of gaseous pollutants seem to be very effective in destroying organic particulates. With lead-free fuel, nearly all of the exhaust particulate matter is organic. It is therefore anticipated that the use of catalysts, especially since 6uch use apparently must be accompanied by the use of lead-free fuel, will eliminate the problem of exhaust particulates. Particulate emissions from attrition of the catalyst itself, by chemical attack, exfoliation, pellets wearing against each other, etc., should perhaps be considered, especially in view of the fact that such material is, after all, a catalyst. -11- 6000 0625 PRODUCED BY FORD