The effect of hydrogen addition to compressed natural gas on performance and emissions of a DI diesel engine by a numerical study J. Zareei a,* , M. Haseeb b , K. Ghadamkheir a , S.A. Farkhondeh a , A. Yazdani a , K. Ershov c a Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad b Taylors Business School, Taylors University Lakeside Campus Jalan Taylors Subang Jaya Selengor, Malaysia c Department of Propaedeutics of Dental Diseases, Sechenov University, Moscow highlights  Effect of adding hydrogen to a CNG fuel on performance and exhaust emissions.  Hydrogen addition is beneficial for converting the fuel’s chemical energy into power.  Engine performance increased with a higher fraction of 30% in HCNG mixtures in comparison to Pure Diesel and CNG.  NOx emission increased with increase of hydrogen in HCNG but HC, and Soot emissions decreased. article info Article history: Received 7 June 2020 Received in revised form 1 September 2020 Accepted 4 September 2020 Available online xxx Keywords: Hydrogen Natural gas Emissions Engine performance Alternative fuel abstract Diesel engines are the most commonly used internal-combustion engines. Due to incom- plete combustion of fossil fuels, engine performance and emissions output are unsuitable. On the other hand Emissions of greenhouse gases using fossil fuels in internal-combustion engines are considered to be the main cause of climate change. Thus to find an alternative fuel to eliminate or reduce CO 2 and exhaust emissions is an urgent concern worldwide. Superabundant and readily available, makes hydrogen an attractive alternative to fossil fuels. In this study, a 3-cylinder turbocharged diesel engine is converted into CNG direct- injection engine and then hydrogen as a fuel enrichment added to CNG. AVL Fire™ Soft- ware is used to simulate the engine at different engine speeds, injection pressure, and Air/ Fuel ratios. The results confirm that adding hydrogen to CNG improves brake thermal ef- ficiency and engine brake power, reduces brake specific fuel consumption as well as the diminution in HC and Soot but also increases the NO x . © 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Introduction Following the 1970s Arab oil embargo against the west, rendering a sharp increase in oil prices, fuel consumption * Corresponding author. E-mail address: javadzareei@um.ac.ir (J. Zareei). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (xxxx) xxx https://doi.org/10.1016/j.ijhydene.2020.09.027 0360-3199/© 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article as: Zareei J et al., The effect of hydrogen addition to compressed natural gas on performance and emissions of a DI diesel engine by a numerical study, International Journal of Hydrogen Energy, https://doi.org/10.1016/j.ijhydene.2020.09.027