JFET_V5_N2_RP5 Mohd. F. Shabir P. Tamilporai B. Rajendra Prasath Journal on Future Engineering and Technology 2230 – 7184 5 2 32 41 Low Heat Rejection, Miller Cycle, Internal Exhaust Gas Recirculation, Oxides of Nitrogen Diesel engines are the best prime movers with substantial inherent energy transfer to the coolant. To minimize this heat transfer to the coolant, Low Heat Rejection (LHR) concept was developed. At the same time, drawbacks were also encountered because of the very high combustion chamber temperatures in LHR engines. Heavy exhaust blow-down energy and high Oxides of Nitrogen (NO ) emissions were two among them, which has lead to decrease in thermal x efficiency and inability to achieve legislative emission levels. To realize the advantages of LHR diesel engine, the cycle calculations were formulated and developed under numerical simulation. The parametric studies were carried out with closer duration of each crank angle degree. In the engine cycle calculations the Internal Exhaust Gas Recirculation (iEGR) and extended expansion processes were coupled to minimize the drawbacks of LHR engine. The iEGR is accomplished with the secondary exhaust valve opening during suction stroke and the extended expansion by incorporating the Miller cycle by delaying the IVC timing. The heat release is calculated using preparation rate and reaction rate, considering two-zone combustion. The total heat transfer is calculated using Annand's combined heat transfer model. During combustion, chemical equilibrium of oxygen and nitrogen were determined to calculate the nitric oxide formation rate, assuming ZELDOVICH mechanism. The results of the numerical simulation were validated by conducting experiments in a Conventional and as well as LHR turbocharged four cylinder DI diesel engine. Modification of gas exchange has resulted in decrease in nitric oxide emissions along with a considerable improvement in thermal efficiency under LHR condition. November 2009 - January 2010 Copyright © 2010 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=1093