Effect of an emission-reducing soluble hybrid nanocatalyst in diesel/ biodiesel blends on exergetic performance of a DI diesel engine Mortaza Aghbashlo a, * , Meisam Tabatabaei b, c, ** , Pouya Mohammadi c , Mehrdad Mirzajanzadeh d , Mehdi Ardjmand e , Alimorad Rashidi c, f a Department of Mechanical Engineering of Agricultural Machinery, Faculty of Agricultural Engineering and Technology, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran b Microbial Biotechnology Department, Agricultural Biotechnology Research Institute of Iran (ABRII), P.O. Box: 31535-1897, AREEO, Karaj, Iran c Biofuel Research Team (BRTeam), Karaj, Iran d Department of Chemical Engineering, Science & Research Branch, Islamic Azad University, Tehran, Iran e Department of Chemical Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran f Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), Tehran, Iran article info Article history: Received 11 February 2015 Received in revised form 23 February 2016 Accepted 26 February 2016 Available online xxx Keywords: Diesel/biodiesel blends Diesel engine Exergy efficiency Exergy destruction Hybrid nano-catalyst Sustainability index abstract The present study was set to explore the effect of a novel soluble hybrid nanocatalyst in diesel/biodiesel fuel blends on exergetic performance parameters of a DI diesel engine. Experiments were carried out using two types of diesel/biodiesel blends (i.e., B5 and B20) at four concentrations (0, 30, 60 and 90 ppm) of the hybrid nanocatalyst, i.e., cerium oxide immobilized on amide-functionalized multiwall carbon nanotubes (MWCNT). Furthermore, the exergy analysis was performed at five different loads and two engine speeds. The results obtained revealed that the exergetic parameters were profoundly influenced by engine speed and load. In general, increasing engine speed and load increased the magnitude of the destructed exergy. Moreover, the exergy efficiency increased by increasing engine load, while it decreased by elevating engine speed. However, the applied fuel blends had approximately similar exergetic efficiency and sustainability index. Interestingly, a remarkable reduction in emissions was obtained by incorporating the soluble catalyst nanoparticles to the diesel/biodiesel blends. Thus, it could be concluded that the diesel/biodiesel blends containing amide-functionalized MWCNTs-CeO 2 catalyst might substitute the use of pure diesel fuel without any unfavorable change in the exergetic performance parameters of the DI engines. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction The widespread application of fossil-originated fuels is consid- ered unsustainable because such fuel resources are rapidly depleting and their role on increasing environmental pollutions is well-known [1]. Hence, many surveys have been performed to find various renewable resources to sustainably meet the growing global energy demands while minimizing the environmental im- pacts [2,3]. Biodiesel is among the most promising renewable en- ergy carriers and has been extensively investigated as a clean burning alternative to petro diesel. However, the drawbacks of biodiesel including power reduction as well as increased fuel consumption and NO x emission [4] decelerate its extensive utili- zations. Such unfavorable properties are related to the physico- chemical properties of biodiesel [5]. Therefore, numerous efforts have been put into improving bio- diesel properties. Among the strategies investigated has been the application of a wide variety of metal-based additives. For example, Keskin et al. [6] used Ni and Mn to improve pour point and vis- cosity. In different investigations, Gürü et al. [7,8] applied Ni and Mg and Çaynak et al. [9] employed organic based Mn additive to reduce viscosity, pour point, and flash point. In addition, nanoparticle- loaded fuels have also been studied in order to improve diesel and biodiesel combustion. Kao et al. [10] added aqueous aluminum nanofluid to reduce soot and NO x emission. In another survey, Sadhik Basha and Anand [11] used aluminum nanoparticle to improve engine performance and reduce pollutants emission. * Corresponding author. ** Corresponding author. Biofuel Research Team (BRTeam), Karaj, Iran. E-mail addresses: maghbashlo@ut.ac.ir (M. Aghbashlo), meisam_tab@yahoo. com (M. Tabatabaei). Contents lists available at ScienceDirect Renewable Energy journal homepage: www.elsevier.com/locate/renene http://dx.doi.org/10.1016/j.renene.2016.02.077 0960-1481/© 2016 Elsevier Ltd. All rights reserved. Renewable Energy 93 (2016) 353e368