No abstract

No abstract

The European Union made new CO2 limits for heavy-duty vehicles mandatory in 2019, aiming to reduce the average tailpipe CO2 emissions by 15% in 2025 and by 30% in 2030, relative to the 2019 baseline. To meet these challenges, new technologies are needed to further reduce the fuel consumption of new heavy-duty trucks (“tank to wheel”) by using more efficient engines. The present study shows the pathways to improve thermal efficiency through better mixture formation and air utilization. This is achieved by designing a new piston bowl shape that has been numerically optimized iteratively to improve the air/fuel mixing by carefully considering the interaction between the fuel spray plume and the piston bowl. The CFD model was calibrated using data from experimental studies with a heavy-duty single-cylinder diesel engine in best efficiency and rated power operation. Heat transfer and turbulence models are studied to determine their influence on the combustion process and NOx emissions. Indicated thermal efficiency and air utilization were used to evaluate the performance of the piston bowl shape. For three different bowl shapes, the fuel spray interaction with the piston bowl was investigated and compared with the base bowl shape with a compression ratio CR = 18.3. Moreover, the effect of a higher CR of 21 on performance and mixture formation was analyzed for the optimized bowl shape. The higher CR of 21 was attained by geometrically similar reduction of the optimized piston bowl. The results of the numerical and experimental investigations show that a CR of 21 leads to an increase in the indicated thermal efficiency of ∼ 3% in absolute values.

This paper introduces the work of the joint project "Robust and Efficient processes and technologies for Drop-In renewable FUELs for road transport" (REDIFUEL). The overall aim is to enable the utilization of various biomass feedstocks for an ultimate renewable EN590 diesel biofuel in a sustainable manner. REDIFUEL's ambition is to develop new technologies, solutions and processes to reach high conversion efficiencies for renewable fuel production. The proposed drop-in biofuel contains high-cetane liquid (C11-C21) bio-hydrocarbons and C6-C11 bioalcohols showing exceptional combustion and pollutant mitigation performance. Environmental and social aspects are also considered by carrying out a comprehensive Biomass-to-Wheel performance analysis. First artificial fuel samples simulating the final product have been synthesized and analyzed with regard to fuel relevant properties, showing very promising results.

No abstract