Simulation of the impact of diesel-biodiesel and diesel-HVO (Hydrotreated vegetable oil) fuel blends on regulated and unregulated emissions in a vehicle under Colombian driving cycles

Abstract

ABSTRACT: Vehicle exhaust emissions, a significant challenge in densely populated urban areas, adversely impact air quality and human health. The use of renewable fuels, particularly biodiesel (BD) and hydrotreated vegetable oil (HVO), has emerged as a promising solution. BD, blended seamlessly with fossil diesel, is gaining popularity globally, with over 60 countries that have implemented their use. In Colombia, a palm oil biodiesel industry aligns with the nation's commitment to sustainability. Resolution 40103 of Colombia further supports renewable fuels, encompassing not only BD but also HVO, an innovative renewable diesel, which exhibits superior properties compared to traditional biodiesel, resulting in reduced exhaust regulated emissions and improved engine performance. However, information regarding emissions of highly toxic and unregulated pollutants, such as Polycyclic Aromatic Hydrocarbons (PAHs) and carbonyls, remains limited. Furthermore, evaluating emissions under both steady-state and transient conditions is crucial for understanding the true impact of renewable fuels. In particular, Colombian driving cycles, representative of heavy traffic conditions in urban areas, could play a pivotal role in assessing impact of biofuels on performance and emissions. This research, through modeling and simulation using GT-Suite, evaluates the effects of diesel-biodiesel and diesel-HVO fuel blends on both regulated and unregulated emissions under actual Colombian driving conditions. The study focuses on 20 vol.% blends (B20 and HVO20), chosen for their representativeness in balancing operability, performance, and regulated emissions benefits. The methodology involves a comprehensive review of the literature, input data collection, experimental measurements, construction and calibration of models, and analysis of results. While the engine model shows high precision in predicting combustion emissions for regulated pollutants and performance parameters, predicting unregulated emissions remains challenging. The vehicle model, however, exhibits a strong correlation between simulated results and experimental measurements, particularly under transient conditions. It was found that the use of B20 led to a decrease of 27 – 35% in particle number (PN) emissions, and 12 – 20.5% in unburned hydrocarbon (HC) emissions with respect to Ultra Low Sulfur Diesel (ULSD), while the effect was not significant in carbon monoxide (CO) and carbon dioxide (CO2), and a slight increase in nitrogen oxides (NOx) emissions was observed. The use of B20 decreased PAH emissions by up to 33.2%, while it did not have a significant impact on carbonyl emissions. The use of HVO20 did not have a significant impact on CO, CO2, NOx and PN emissions, while a positive impact was observed on HC emissions, with reductions ranging between 15.6% and 19.5%. Consideration of road slope within the driving cycle had the most significant effect on emissions, increasing them with all fuels. The results of this study aim to provide valuable insights into the environmental performance of alternative fuel blends, considering the Worldwide harmonized Light vehicles Test Cycle (WLTC) and unique characteristics of Colombian driving cycles and their implications for the transportation sector.