Automotive Science and Engineering

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Changing various parts of different types of engines in the maintenance phase was always a remarkable question. Purpose of the present study is identifying the performance and emissions of a diesel-fueled engine (OM457) before and after replacing connecting rod and crankshaft with another engine (OM444) in the same engine family.

At the first step, a solid model was made then some CFD analyses were done and, results were compared with previous studies for validation after that in the CFD modeling the impact of these parts replacement were observed, and the performance and emissions of this engine were compared with data before replacements.

As the result of these replacements, compression ratio and performance were decreased. HC and CO were increased due to lower air-fuel ratio, and NO_X was decreased because of the lower temperature of in cylinder. Lowering the CR of a diesel engine will reduce the NOx emission numerously but the increase in other emissions will be slight. So for the environment issues lowering the CR will be a practical and low cost method.

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Many efforts have been made to increase power and reduce emissions from internal combustion engines. For this purpose, the internal combustion engine subsystems are examined via many studies, and the effective parameters in each of them are analyzed. One of these subsystems is the air inlet and outlet to the combustion chamber, the most important part of which is the manifold. In the present study, using one-dimensional modeling of the OM457 heavy diesel engine in the GT SUITE software environment, the effect of geometric parameters of cylinder runner’s length - cylinder runner’s transverse distance as well as plenum’s depth on the performance and the emissions of this engine has been investigated. During this study, it was concluded that increasing the volume of the plenum not only improves the engine’s output but also reduces the emission of pollutants produced. Also, increasing the length of the cylinder runner increased the engine power. The change in the transverse distance of the cylinder runners did not have a significant effect on the power and pollutants of the sample engine. It was also observed that in similar geometric changes, the effect of changing the input manifold is significantly greater than the output manifold level.