An experimental study on the impact of biodiesel origin on the regulated and PAH emissions from a Euro 4 light-duty vehicle Evangelos Bakeas a , Georgios Karavalakis b,⇑,1 , Georgios Fontaras c , Stamos Stournas b a Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15771 Athens, Greece b Laboratory of Fuels Technology and Lubricants, School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytechniou Str., Zografou Campus, 15780 Athens, Greece c European Commission, Joint Research Centre, Institute for Environment and Sustainability, Via E. Fermi 2479, 21020 Ispra, Italy article info Article history: Received 7 July 2010 Received in revised form 7 July 2010 Accepted 19 May 2011 Available online 14 June 2011 Keywords: Biodiesel Exhaust emissions Oxidation PAH Driving cycles abstract This study investigates the impact of mid-high biodiesel blends on the criteria and PAH emissions from a pick-up diesel vehicle. The vehicle was a Euro 4 (category N1, subclass III) compliant common rail light duty vehicle fitted with a diesel oxidation catalyst. Emission and fuel consumption measurements were performed on a chassis dynamometer using constant volume sampling (CVS) technique, following the European regulations. All measurements were conducted over the NEDC and Artemis driving cycles. Aim- ing to evaluate the fuel impact on emissions, a soy-based biodiesel, a palm-based biodiesel, and an oxi- dized biodiesel obtained from used frying oils were blended with an ultra low sulfur diesel at proportions of 30%, 50% and 80% by volume. CO 2 emissions and fuel consumption exhibited increases with biodiesel over all driving conditions which ranged up to 5%. NO x emissions were found to be above the Euro 4 limit and increased with biodiesel between 5% and 10% except for the blends prepared with the palm-based methyl ester. The emissions of PM, HC, and CO decreased with the addition of biodiesel reaching maxi- mum reductions in the order of 10%, 30% and 20% respectively; however, some increases were observed over the NEDC which may be attributed to cold-start. Sharp increases in most PAH, nitro-PAH and oxy- PAH compounds were observed with the application of biodiesel. These increases were particularly noticeable with the use of the oxidized blends, a phenomenon that it is related with the type and quality of this fuel. The emissions were also affected by the operating conditions of the engine. It was found that most PAH compounds were decreased as the mean speed and load of the driving cycle increased. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Vehicle emissions have long been recognized as one of the most important anthropogenic sources to both gaseous and particulate emissions, and of toxic species such as polycyclic aromatic hydro- carbons (PAHs). Diesel vehicles are a major source of these emis- sions, particularly in the case of nitrogen oxides (NO x ) and particulate matter (PM) [1]. Consequently, concerted efforts have been made to reduce the impact of vehicular emissions on ambient air quality, including the use of alternative fuel formulations. Fatty acid methyl esters (FAMEs), collectively referred to as biodiesel, have received a growing interest since biodiesel offers several fuel advantages over petroleum diesel, including improved lubricity, a higher flash point, lower toxicity, biodegradability, and less contribution to the greenhouse effect [2,3]. Many studies have examined emissions from biodiesel and revealed that emissions of PM, unburned hydrocarbons (HC) and carbon monoxide (CO) are reduced relative to petroleum diesel [4–6]. However, the positive or negative effect on the aforemen- tioned pollutants varied significantly among vehicles, engine tech- nology and test cycles. Previous studies suggest poor benefit in these emissions with biodiesel over the NEDC mainly due to the cold-start effect and phenomena related to oxidation catalyst effi- ciency [7,8]. Many studies reported an increase in NO x emissions with the application of biodiesel. The cause of the increased NO x emissions for biodiesel is still inconclusive; however, a number of fuel properties have been shown to affect emissions of NO x , including different fuel chemistry (bulk modulus, degree of unsat- uration, cetane number) and fuel spray characteristics [9,10]. The information given in literature about the effect of biodiesel on the emissions of PAH compounds is limited and often contradic- tory. PAHs are a class of complex organic molecules, which include 0016-2361/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2011.05.018 ⇑ Corresponding author. Tel.: +1 951 781 5799; fax: +1 951 781 5790. E-mail address: gkaraval@cert.ucr.edu (G. Karavalakis). 1 Present address: University of California, Riverside, Bourns College of Engineering, Center for Environmental Research and Technology (CE-CERT), CA92507, USA. Fuel xxx (2011) xxx–xxx Contents lists available at ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel Please cite this article in press as: Bakeas E et al. An experimental study on the impact of biodiesel origin on the regulated and PAH emissions from a Euro 4 light-duty vehicle. Fuel (2011), doi:10.1016/j.fuel.2011.05.018