Effect of ethanol/water blends addition on diesel fuel combustion in RCM and DI diesel engine Mohamed Nour a,c,⇑ , Hidenori Kosaka b , Susumu Sato b , Mahmoud Bady d,e , Ali K. Abdel-Rahman a,d , Kenta Uchida b a Energy Resources Engineering Department, Egypt-Japan University of Science and Technology E-JUST, New Borg El Arab, Alexandria, Egypt b Department of Mechanical and Aerospace Engineering, Tokyo Institute of Technology, Tokyo, Japan c Department of Mechanical Engineering, Benha Faculty of Engineering, Benha University, Benha, Qalubia, Egypt d Mechanical Engineering Department, Assiut University, Assiut 271516, Egypt e Mechanical Engineering Department, Islamic University of Medina, Medina, Saudi Arabia article info Article history: Received 20 April 2017 Received in revised form 9 July 2017 Accepted 10 July 2017 Keywords: Ethanol/water mixture Combustion analysis Two-color method Emission characteristics RCM Diesel engines abstract The effect of ethanol/water blends addition on diesel fuel combustion and emissions is investigated experimentally in this study using optical diagnostics. Basic study is performed using rapid compression machine (RCM) under CI conditions. The tested ethanol energy fractions varied in the range of 10–40% of the total added fuel energy, while water volume ratios varied in the range of 10–40% of the injected etha- nol. Ethanol and water were evaporated before entering the combustion chamber to eliminate their endothermic effect. Results reveal that addition of ethanol/water blends to diesel fuel results in longer ignition delay and promote the apparent heat release rate (AHRR) at the premixed combustion phase compared to absolute ethanol addition. Additionally, soot and NO x emissions are reduced with etha- nol/water addition compared to absolute ethanol addition and neat diesel combustion. The basic study is then extended to investigate the effect ethanol/water blends addition on diesel fuel combustion using single cylinder diesel engine. Waste heat in exhaust manifold is utilized to vaporize ethanol/water blends before combustion. Results reveal that ethanol/water blends injection leads to increase in peak cylinder pressure, indicated mean effective pressure (IMEP), and AHRR at premixed combustion phase. Additionally, the ignition delay increased with ethanol/water addition. NO x emission is decreased up to 88% along with a reduction in soot by 50%. The lower ethanol to water volume ratios show better com- bustion efficiency, IMEP, NO x and soot emissions compared to the higher ethanol to water volume ratios. The addition of water to ethanol leads to longer ignition delay and lower soot concentrations compared to absolute ethanol. Additionally, water addition reduces the flame temperature, which leads to NO x reduction. Ó 2017 Elsevier Ltd. All rights reserved. 1. Introduction Global concerns about depletion of conventional oil resources, deterioration of the environment, and security of fuel supply have motivated research and development of internal combustion engines. Diesel engines are widely used in transportation, electrical power generators, and pumps and considered as the primary source of NO x and soot emissions. However, there is a tradeoff rela- tionship between soot and NO x formation in diesel engines and simultaneous reduction of both is difficult [1]. Advanced low- temperature combustion strategies offer prominent benefits of simultaneous reduction of both NO x and soot emissions, with low specific fuel consumption [2]. The potential of using alternative fuels in diesel engines with advanced combustion strategies is imperative. The important crite- rion that should exist in alternative fuels used in CI engines is the high cetane number [3]. Despite the low cetane number of ethanol, it has been studied for decades in combination with diesel fuel because of its renewable resource base and oxygenated properties, which can significantly reduce the soot emissions [4,5]. The NO x emissions also decreased due to ethanol’s high latent heat of vaporization which reduces the flame temperature. The other http://dx.doi.org/10.1016/j.enconman.2017.07.026 0196-8904/Ó 2017 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Faculty of Engineering at Benha, Benha University, Egypt-Japan University of Science and Technology (E-JUST), Egypt. E-mail addresses: mohamed.farag@ejust.edu.eg, mohamed.nour@bhit.bu.edu.eg (M. Nour). URLs: http://www.beng.bu.edu.eg, http://www.ejust.edu.eg (M. Nour). Energy Conversion and Management 149 (2017) 228–243 Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman