Methodology improvements to simulate performance and emissions of engine transient cycles from stationary operating modes: A case study applied to biofuels

• Published in: Fuel (Guildford) 2022-03, Vol.312, p.122977, Article 122977
• Main Authors: Cruz-Peragón, Fernando, Torres-Jiménez, Eloísa, Lešnik, Luka, Armas, Octavio
• Format: Article
• Language: English
• Subjects: Accuracy; Biodiesel; Biodiesel fuels; Biofuels; Carbon monoxide; Cold start correction function; Cold starts; Design of experiments; Diesel; Diesel engines; Diesel fuels; Emissions; Exergy; Exhaust gases; Flow rates; Fractional factorial design; Light duty diesel engine; Mass flow rate; Methodology; Nitrogen oxides; Optimality criteria; Optimization; Orthogonality; Parameter estimation; Particulate emissions; Particulate matter; Photochemicals; Rapeseed; Raw materials; Simulation; Soybeans; Sunflowers; Test procedures; Transient cycle
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2021.122977

•Engine/vehicle transient responses can be estimated from 13 stationary regimes.•The methodology provides accurate results regardless of the fuel tested.•The improved methodology increases the accuracy of the estimated parameters.•A new fitting function to simulate the cold start effect is implemented.•The boundary definition in the [n,M] domain influences the model accuracy. In the present study engine/vehicle responses from a standardized transient test cycle are estimated using 13 stationary operating regimes following a previously developed methodology. The main advantage of the methodology tested is that allows obtaining an estimation of transient parameters in a stationary test bench, which requirements are much less demanding than those of the transient test bench. The objectives are: in one hand, to demonstrate that the methodology correctly estimates engine responses regardless of the fuel tested, as it is proposed in a previous paper and, on the other hand, to improve the methodology and the accuracy of the estimated parameters. The fuels tested are renewable fuels from different raw materials (biodiesel from rapeseed, sunflower, and soybean), and diesel fuel as the reference. Biodiesels were tested neat and blended (30% v/v) with diesel fuel. The engine is a common-rail light-duty one, and the standardized testing procedure used to illustrate the implementation of the methodology is the New European Driving Cycle (NEDC). Two design of experiments (DoE) of 13 runs each were analyzed. One of the DoE tested was proposed for characterizing the NEDC, referred as to CTDoE design, while the other one is a five-level fractional factorial design (FFDoE) that adequately matches the optimality criteria of orthogonality, D-optimal criterion, rotatability, and space-filling. The original methodology was improved by the implementation of a new fitting function that simulates the cold start effect over the engine parameters and by an new definition of the boundary in the [n,M] domain. These improvements showed significantly higher accuracy of the estimated engine parameters obtained, both instantaneous and accumulated, respect to the original methodology. The results obtained based on the application of the FFDoE design support the feasibility of the methodology tested. Engine performance and regulated emissions responses, such as intake air and fuel mass flow rate, thermomechanical exergy rate, exhaust gas residual heat rate, total hydrocarbons (THC), nitroge