Injection parameter optimization by DoE of a light-duty diesel engine fed by Bio-ethanol/RME/diesel blend Carlo Beatrice ⇑ , Pierpaolo Napolitano, Chiara Guido IstitutoMotori CNR, Viale Marconi 8, 80125 Naples, Napoli, Italy highlights  Effects of a bio-ethanol/biodiesel/diesel blend on Euro 5 diesel engine.  Potentiality of the combustion control technology with alternative fuels.  Application of the Design of Experiment methodology for engine performance improvement.  Analysis of main injection parameters affecting emissions at low load engine conditions.  Pollutant and GHG emission reduction with bio-ethanol/biodiesel/diesel blend with engine re-calibration. article info Article history: Received 22 May 2013 Received in revised form 19 July 2013 Accepted 24 July 2013 Available online 23 August 2013 Keywords: Bio-ethanol Diesel combustion control Design of Experiments Emissions reduction GHG emission reduction abstract An experimental campaign has been devoted to characterize the engine fuelled by the ethanol based blend highlighting the advantages and issues related to the bio-ethanol use. The effects of the most important injection settings on the engine performance have been detailed, applying a Design of Exper- iment (DoE) method, to identify the most important parameters affecting emissions and the potentiality offered by a proper engine calibration to optimize the ethanol blend use. The tests were performed on a 2.0 L Euro 5 diesel engine, in steady-state at partial and full-load conditions, burning two fuel blends: a Rapeseed Methyl Ester (RME)/diesel blend with 10% of biodiesel by volume, assumed as reference fuel, and a bio-ethanol/RME/Diesel with 20% of bio-ethanol and 10% of biodiesel by volume. Emission mea- surements with standard Euro 5 calibration showed the well-know effects of ethanol blending to diesel fuel: a strong smoke emissions reduction in all tested conditions, together with a decrease of NOx exhaust concentration. An increment of CO and HCs emissions for bio-ethanol blends were also found, mainly at low load conditions. This issue has been investigated performing a specific test campaign inspired to the DoE method. Such activity identified in the calibration of the pilot injection quantity and rail pressure values the most influential factors in the gaseous unburned reduction. By the adoption of an optimized calibration, identified by DoE results, gaseous emissions on NEDC cycle were significantly reduced with respect to the reference calibration, matching the HCs and CO Euro 5 limits and approach- ing both PM and NOx Euro 6 emission levels. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction In the effort to satisfy the goal of saving energy and protecting the environment, bio-ethanol (bio-EtOH) appears as one of the alternative fuels for internal combustion engines. Even if its most common use is for gasoline engine applications, the interest in burning ethanol (EtOH) in diesel engine is newly increasing. In- deed, recently, the second generation bio-EtOH, which utilizes lig- nocellulosic biomass derived from forest residues, wood wastes, solid wastes, etc. has received much interest because the adopted feedstock is abundant, low-cost and above all does not compete with food crops [1]. As known, bio-EtOH offers the benefit of reducing the net emis- sions of greenhouse gases and it can represent a further option to other alternative fuels, like methyl/ethyl esters derived from vege- table oil or animal fat (first generation biodiesels) or Fischer–Trop- sch fuels (second generation biodiesels). Thanks to these characteristics, in the common aim to reduce the world’s depen- dence on crude oil, EtOH use in diesel engines have been widely investigated in the last years [2]. Focusing on the use of EtOH in compression ignition (CI) en- gines, some critical aspects have to be taken into account. The physical and chemical characteristics of ethanol (low lubricity, low cetane number, high hygroscopicity as example) do not make 0306-2619/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.apenergy.2013.07.058 ⇑ Corresponding author. Tel.: +39 0817177186; fax: +39 0812396097. E-mail addresses: c.beatrice@im.cnr.it, carlo.beatrice@cnr.it (C. Beatrice). Applied Energy 113 (2014) 373–384 Contents lists available at ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy