Emission characteristics of a converted diesel engine using ethanol as fuel Murat Çetin a, ⁎, Fikret Yüksel b , Hüsamettin Kuş a a Department of Automotive, Vocational High School, Erzincan University Erzincan 24109, Turkey b Mechanical Engineering, Engineering Faculty Atatürk University Erzurum, 25240, Turkey abstract article info Article history: Received 13 February 2009 Revised 17 April 2009 Accepted 1 October 2009 Keywords: Alternative Fuels Combustion Engines Ethanol Emissions The aim of this study is to investigate the suitability of neat ethanol (95%) as an alternative fuel in an engine converted from diesel to ethanol, and experimentally determine the effect of different main fuel jets at carburetor on engine exhaust emissions and fuel consumption at high engine compression ratio (CR) of 14. For this purpose, three different diameter main fuel jets (1.40 mm, 1.50 mm, 1.60 mm) were used for ethanol fuel tests in a naturally aspirated four-stroke pre-chamber diesel engine. Tests were made at full-load conditions at speeds between 1200 and 2600 rpm at intervals of 400 rpm. In addition, cold-start system was developed and engine could be operated at reliable idle speed and medium speed down to 0 °C ambient temperatures. The results show that HC emissions increase with increasing fuel jet diameter and CO, PM and HC emissions reduce significantly at idle speed and medium engine speeds. © 2009 International Energy Initiative. Published by Elsevier Inc. All rights reserved. Introduction The use of alternative fuels in engines has become increasingly widespread during recent decades, both for fuel supply and environmental reasons. Many researchers have focused on alternative fuels in diesel engines (Ajav et al., 1998; Makame et al., 2001; Nwafor, 2002; Altın et al., 2001; Black and Donaldson, 1998). Ethanol, a reneweble fuel obtained from biomass, has been extensively used in spark-igntion internal combustion engines, both in gasoline blends as well as in neat form. Brazil leads this experience but many other countries also use ethanol, especially in blends with gasoline. Ethanol was the first fuel among the alcohols to be used to power vehicles in the 1880s and 1890s. Henry Ford presented it as the fuel of choice for his automobiles during their earliest stages of development and in the early days of engine engineering, alcohols were used as octane improvers for gasoline or replaced gasoline (Thring, 1983; Al-Hasan, 2003). The combustion of ethanol in internal combustion engines reveals some attractive properties of this fuel: low black smoke (smog), NO x (nitrogen oxides) and HC (hydrocarbon) emissions. Because of its high knock resistance, ethanol is very well suited for use in spark ignition (SI) engines and is used as an antiknock component and as a gasoline extender. On the other hand, because of its insufficient auto ignition quality, pure ethanol is unsuitable for combustion in compression ignition engines. However, the inflammability of alcohol at low temperatures is very poor due to high heat of evaporation and high vapour pressure (Quissek et al., 1992; Yüksel and Veziroğlu, 1991; Alasfour, 1997; Hardenberg and Schaefer, 1981). This causes serious problems with the use of neat ethanol in SI engines at sub zero temperatures. Table 1 shows the fuel properties of diesel and ethanol. Ethanol use in diesel engines has generally involved converting the diesel engine to a spark-ignition engine, and this permits pure ethanol to be used. Alternatively diesel–ethanol blends can be used in diesel engines (Pirouspanah and Barkhordarion, 1996). There are many studies on the utilization of ethanol in compres- sion ignition engines. Weidman and Menard (1984) tested the performance and emissions characteristics of ethanol–diesel blends in diesel engines. In a dual-fuel diesel engine developed for use with ethanol as a secondary fuel, ethanol in directly introduced into the air intake (called ethanol fumigation) and the ethanol–air mixture transported into the engine cylinder. Broukhiyan (1981) tested an indirect injected diesel engine by using ethanol fumigation supplied with 50% of the total energy and observed decreasing the mass particulate emitted and NOx emissions all conditions. This can be explained by the fact that oxygen content in the ethanol is effective in improving combustion in a mixture. Hayes et al. (1988) studied ethanol fumigation (30% ethanol in diesel–ethanol blends to the intake air charge) in a six-cylinder turbocharged diesel engine and observed lower NO emissions but higher HC emissions at lower load. Noguchi et al. (1996) introduced vaporized ethanol into a diesel engine as a supplementary fuel, and using different proportions ethanol–diesel fuel blends, they observed that CO and NOx emissions were lower compared to engine operated on diesel fuel. Ajav et al. (1998) tested a four-cylinder diesel engine with ethanol–diesel fuel and methanol–diesel fuel blends and reported that HC, CO emissions increased but NOx emission decreased compared to engine operated with pure diesel fuel. Li et al. (2005) and Merritt et al. (2005) investigated ethanol as one of the oxygenates for blending with diesel Energy for Sustainable Development 13 (2009) 250–254 ⁎ Corresponding author. Fax: +90 446 2266601. E-mail address: mcetin@erzincan.edu.tr (M. Çetin). 0973-0826/$ – see front matter © 2009 International Energy Initiative. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.esd.2009.10.001 Contents lists available at ScienceDirect Energy for Sustainable Development