Optimization of a Multiple Injection System in a Marine Diesel Engine through a Multiple-Criteria Decision-Making Approach

Abstract

In this work, a numerical model was developed to analyze the performance and emissions of a marine diesel engine, the Wärtsilä 6L 46. This model was validated using experimental measurements and was employed to analyze several pre-injection parameters such as pre-injection rate, duration, and starting instant. The modification of these parameters may lead to opposite effects on consumption and/or emissions of nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC). According to this, the main goal of the present work is to employ a multiple-criteria decision-making (MCDM) approach to characterize the most appropriate injection pattern. Since determining the criteria weights significantly influences the overall result of a MCDM problem, a subjective weighting method was compared with four objective weighting methods: entropy, CRITIC (CRiteria Importance Through Intercriteria Correlation), variance, and standard deviation. The results showed the importance of subjectivism over objectivism in MCDM analyses. The CRITIC, variance, and standard deviation methods assigned more importance to NOx emissions and provided similar results. Nevertheless, the entropy method assigned more importance to consumption and provided a different injection pattern.

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“…Each cylinder has 2 inlet and 2 exhaust valves. Previous works [27][28][29][30][31][32][33] describe the CFD model and its validation with experimental results.…”

“…Instead of objective methods, subjective ones are recommended to establish the criteria weights, since experts in the field can directly define them. Objective weighting criteria methods are only recommended when there is no agreement between the experts or when the objectivity is extremely important [27,41]. According to this, this study considers two main requirements: consumption and emissions.…”

Assessment of the Materials Employed in Green Artificial Reefs for the Galician Estuaries in Terms of Circular Economy

“…Several objective methods can be found in the literature to establish the weights through mathematical expressions. Nevertheless, subjective weighting criteria are most commonly used, and objective methods are particularly recommended when there is no agreement among the sets of weights proposed by the experts [128,129]. In any case, a sensitivity analysis of the values defined for the weights is carried out in Section 3.…”

Internal Modifications to Optimize Pollution and Emissions of Internal Combustion Engines through Multiple-Criteria Decision-Making and Artificial Neural Networks

“…In this regard, MCDM (multi-criteria decision-making) constitutes a formal tool for choosing between several alternatives which involve conflicting criteria. MCDM makes decision-making more effective when there are conflicting criteria, and minimizes human intervention in the decision process [ 9 , 10 ].…”