en سوخت های جایگزین Modern Powertrain (hybrid, electric, CNG, bio, ...) پژوهشي Research In this paper, a computational in-cylinder analysis of HCCI diesel engine was carried out using IC Engine FORTE (ANSYS 18.2) software package. The analysis used pre-defined industry standard CHEMKIN format for specifying a chemical reaction mechanism during the combustion duration. The investigation was carried out for the effects of various EGR mass percentages on the thermal and emission characteristics of a diesel engine running on HCCI mode of combustion. It was observed that an increase in EGR concentration resulted in the decrease in peak in-cylinder pressure and temperature and it was also found that when the EGR rates were increased beyond 75% there was no combustion happening within the cylinder. A considerable decrease in the NO_x emissions was found with an increase in EGR mass percentage with almost negligible values when the EGR rates were increased beyond 50%, however there was a slight increase in un-burnt hydrocarbons. HCCI, NOx, EGR, Combustion phasing, Ignition delay, Unburned hydrocarbons 2833 2839 http://ase.iust.ac.ir/browse.php?a_code=A-10-346-1&slc_lang=en&sid=1 Mushtaq Ahmad Rather mushi.3afn_15@nitsri.net 180031947532846002295 180031947532846002295 Yes National Institute of Technology, Srinagar, Kashmir, J&K. INDIA Mohammad Marouf Wani maroufwani@yahoo.com 180031947532846002296 180031947532846002296 No National Institute of Technology, Srinagar, Kashmir, J&K. INDIA