A Study on the Factors Affecting the Uniformity of Urea and Exhaust Gas Using an SCR Simulator

As it is difficult to confirm mixed shape and mixing ratio which depend on the actual mixer inside the SCR, the present study on mixed shape and mixing ratio has been conducted by producing an SCR system simulator. Total 19 sensors were installed and the system was designed not to allow formation of a negative pressure inside the exhaust pipe. The experiment was conducted setting engine rpm, temperature, mixer shape, and distance as the experiment variables. As a result of the experiment, in the case of non-mixer type, a phenomenon was found where urea became locally packed as the exhaust gas and urea were not mixed and, when an R-type mixer was applied, urea was formed being spread on the whole. It was also confirmed that uniformity index was increased by 8 % in average when an R-type mixer was used in comparison to that of the non-mixer type, and the non-mixer type failed to achieve flow uniformity of 90 % or higher while the case where an R-type mixer was used could achieve it when the distance was 20 cm or bigger. Based on such a result, changes in the uniformity of urea and exhaust gas depending on existence of a mixer, exhaust gas temperature, engine rpm, and distance could be confirmed. It is thought that additional studies are required to be conducted later on the effect of a change in the mixer shape on flow uniformity.

Effect of Alternative Fillers on the Properties of Rubber Compounds

The paper is focused on the influence of alternative fillers on rubber compounds properties. Three different types of powder fillers, drinking water treatment sludge (DWTS), perlite and calcium carbonate, were mixed into rubber compound mixtures. The mixtures were composed of STR20, EPDM, zinc oxide, steric acid, paraffin wax, 2-mercaptobenzothiazole (MBT), sulphur, Wingstay L, and filler. The mixtures were mixed in a Kneader type mixer at temperature of 70°C and then continuously mixed using a two-roll mill at temperature of 70°C. The relationships between type and the amount of filler versus properties of rubber compounds were demonstrated. The results showed that tensile and elongation at break of rubber compounds gradually decreased with increasing the amount of filler. Rubber compounds filled with small particle size filler possessed higher tensile strength and elongation at break than those filled with large particle size filler. Values of DIN abrasion loss of rubber compounds prepared under proper mixing condition were not more than 300 mm3. Under appropriate condition, the rubber compounds with DWTS, perlite and calcium carbonate provided sufficiently high shore A hardness (not less than 50 Shore A hardness). Finally, alternative fillers such as DWTS and perlite were expected to replace calcium carbonate in normal formula.

Development of the Self-Lubricating Steels by Compression of Granulated Powders

Self-lubrication composites containing second phase particles incorporated into the volume of the material appears to be a promising solution for controlling friction and wear in modern systems. The objective of this work was the development of steels with low friction coefficient using granulated powders through a precursor (SiC), which generate carbon nodules in a ferrous matrix. The studied alloy composition was Fe+0,6C+3SiC using 2 wt.% of EVA as binder. In this study, the influence of the average size of the iron particles and silicon carbide (SiC) in the microstructure, mechanical and tribological properties was evaluated. The powders were first mixed in a "Y" type mixer, granulated drum, compressed and sintered in plasma in a single thermal cycle assuring binder extraction and sintering of components. The achieved results were close to those of alloys of the same composition produced via powder injection molding (PIM) but with processing time and cost close to those of conventional powder metallurgy (PM). Materials with yield strength of 250 MPa, durability of 2800 Nm and 0.11 friction coefficient were obtained.