Corrosion and air pollution from diesel exhaust.

There is widespread public concern, often strongly expressed, over the fumes and black exhaust emitted from diesel vehicles. Such emissions are particularly noticeable in traffic jams, road tunnels, badly ventilated garages and on hilly roads. These emissions are injurious to humans and other living beings; the black dirt and acidic smuts emitted from diesel exhaust are deposited on nearby surfaces corroding metal works, disfiguring buildings and damaging vegetation. With the growing volume and density of road traffic, the problem is becoming increasingly serious. The present study is an investigation into corrosion and atmospheric pollution due to diesel exhaust. In this study an attempt is made towards reducing the concentrations of the undesirable constituents in the exhaust gases by (i) treating the fuel prior to its admission into the cylinder and (ii) treating the exhaust gases before their discharge into the atmosphere. Accordingly, various additives are added in various dosages to the fuel or are injected into the exhaust gas stream in a specially designed afterburner and the effects of these additives on the concentrations of the undesirable constituents in the exhaust are studied. The results of three representative additives, viz: Isoamyl nitrate (X), Aniline (Y) and Cyclohexane (Z) only are reported in this thesis. The effects of additives in the fuel on the cetane No. of the base fuel, the concentrations of CO, formaldehyde, smoke, oxides of nitrogen and the corrosion and deposits due to the exhaust gases are investigated. It is shown that significant reduction in the concentrations of the above mentioned constituents could be brought about by the use of certain additives in their optimum dosages. The side effects of these additives on engine performance (fuel consumption and engine running conditions) are also investigated. The effects of injecting the three representative additives mixed with heated air into the exhaust gas stream in the specially designed afterburner on the concentrations of CO, formaldehyde, smoke, oxides of nitrogen and oxides of sulphur are investigated (this technique has not been attempted with diesel exhaust prior to the present work). It is shown that the injection of these additives into the exhaust gases reduces the concentrations of the undesirable constituents in the exhaust gases except that of oxides of nitrogen, which increased. However, the effects of the additives are only noticeable at higher engine loads where the concentrations of these constituents are generally high. All tests were carried out on a medium speed, four stroke, single cylinder indirect injection compression ignition engine with fixed injection timing