On the issue of reducing nitrogen oxide emissions by diesel internal combustion engines

Introduction. The article dwells on the problem of reducing emissions of nitrogen oxides contained in the exhaust gases (exhaust) of diesel internal combustion engines (ICE) of vehicles. In their operation when controlling harmful substances it is necessary to take into account the local impact of emissions on settlements located near highways. It is noted that there is a problem of high pollution with nitrogen-containing emissions not only of the settlements environment through which highways pass, but of vehicles drivers as well.

The purpose of the study was to analyze the operation of the SCR-NH₃ neutralization system by supplying urea to the exhaust gas of diesel ICEs, as well as the study of the supplying urea method at its injection into the cylinders of the diesel ICE during the gas exhaust cycle.

Methodology and research methods. Studies show that the most important factor is the thermal effect on the reaction process which determined the effective neutralization reaction on a diesel ICE catalyst. The main contributions to the total NO_x emissions are made by rated power modes of the internal combustion engine and the maximum torque modes. The relationship between the maximum NO_x concentrations at M_k.max and N_e.max on the total NO_x emissions in the 13-step cycle of UN Regulation No. 49 was demonstrated.

Scientific novelty and results. The disadvantages of the SCR-NH₃ neutralization method have been analyzed. In this regard, it was proposed to improve the method of feeding urea and fuel into the cylinders of a diesel engine by means of a two-channel nozzle. Additional advantages could be obtained by injecting urea into the internal combustion engine cylinders.

Practical significance. The results of calculating temperature in a diesel engine cylinder with the diesel fuel maximum and minimum cyclic supply at a crankshaft speed corresponding to the maximum torque were presented. The temperature values showed that if urea was injected into the internal combustion engine cylinder after completion of the exhaust valve opening, then the conditions for the thermolysis and hydrolysis process of urea, as well as reducing reactions, would be favorable. The method of neutralizing NO_x emissions contained in the flue gases of thermal stations was analyzed, the purification process of which involved the treatment of flue gases with a solution of urea without the use of catalysts in the temperature range close to the diesel engine cylinder operation.

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