Numerical investigation of the effect of injection timing under various equivalence ratios on energy and exergy terms in a direct injection SI hydrogen fueled engine Arash Nemati a, *, Vahid Fathi b , Ramin Barzegar b , Shahram Khalilarya c a Young Researchers Club, Miyaneh Branch, Islamic Azad University, Miyaneh, Iran b Young Researchers Club, Parsabad Moghan Branch, Islamic Azad University, Parsabad, Iran c Department of Mechanical Engineering, Urmia University, Urmia 57169-33111, Iran article info Article history: Received 21 August 2012 Received in revised form 9 October 2012 Accepted 12 October 2012 Available online 17 November 2012 Keywords: Direct injection SI hydrogen engine First and second law analysis Equivalence ratio Injection timing Exergy Irreversibility abstract In the present article, a Computational Fluid Dynamics (CFD) method and a home-made FORTRAN code have been utilized to investigate the effects of injection timing under various equivalence ratios on the first and second laws of thermodynamics terms in a hydrogen fueled Direct Injection Spark Ignition (DISI) engine. The results show a good agreement with the experimental data. Exergy terms such as exergy transfer with work, exergy transfer with heat, exergy transfer with exhaust gas and fuel chemical exergy were computed based on principles of the second law. Also Entropy generation per cycle is calculated. Special attentions are given to recognize and quantify the irreversibility of combustion process basing on the different injection timings and equivalence ratios. The obtained results indicated that combustion irreversibilities and exhaust gas availability are more affected by varying the equivalence ratio and amount of fuel availability that transfers to environment with exhaust gases increased by increasing the equivalence ratio. Varying the equivalence ratio had different effect on the accumulated work availability reduced to fuel availability at the late and early injection strategies. Also, entropy gener- ation reduced by retarding the hydrogen injection timing and decreasing the equivalence ratio. Changing in injection timing has its maximum effect on F ¼ 0.6 equivalence ratio. Crown Copyright ª 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction Regarding CO 2 and HC emissions and dependency on fossil fuels, hydrogen has major advantages when compared to conventional fuels and internationally, hydrogen is seen as one of the most promising future energy carriers [1]. The concept to use hydrogen as a fuel for IC engines is almost as old as the internal combustion engine itself [2]. The request of improving internal combustion (IC) engine efficiency and emissions is motivating factor to use hydrogen as an alter- native fuel in internal combustion engines [3,4]. The ways of applying hydrogen to automobiles could be mainly divided as fuel cell and hydrogen fueled IC engines. Though the fuel cell gains many advantages, such as high power output and zero emissions while operating, the high cost and short lifetime have become the concern of its wide application [5]. Never- theless, energy policy experts generally believe that utilization of hydrogen as a fuel for transportation sectors more likely * Corresponding author. Tel.: þ98 936 784 8823. E-mail address: nemati.arash.mech@gmail.com (A. Nemati). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 38 (2013) 1189 e1199 0360-3199/$ e see front matter Crown Copyright ª 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijhydene.2012.10.083