Theoretical Investigation of Combustion Process in Dual Fuel Engines at Part Load Considering the Effect of Exhaust Gas Recirculation

The dual fuel engines at part loads inevitably suffer from lower thermal efficiency and higher carbon monoxideand unburned fuel emission. this work is carried out to investigate combustion characteristics of a dual fuel (d l selgas)engine at part loads, using a single zone combustion model with detailed chemical kinetics for combustion ofnatural gas fuel. the authors developed software in which the pilot fuel is considered as a subsidiary zone and a heatsource which is deriving from two superposed wiebe's col i tion functions to account for its contribution to ignitionof gaseous fuel and the rest of total released energy. chemical kinetics mechanism is consisted of 112 reactions with34 species. this quasi-two zone combustion model is able to establish the development of the combustion process withtime and the associated important operating parameters, such ' s pressure, temperature, beat release rate (h.r.r) andspecies concentration. also, this model is able to calculate accumulated heat relea e, ignition delay and combustionduration of gaseous fuel air mixture. therefore this paper is an : tt i t to lnvestigate the combustion phenomenon atpar t loads and using hot exhaust gas reci lation (egr) to improve the above mentioned wbacks and problems.by employing this te in ' u ,it is found that, low percentages of egr. con idering its thermal and radical effects,have the positive effect on performance and emission parameters of dual fuel engines at part loads. predicted valuesshow good agreement with corresponding experimental values in a special engine operating condition (l /4ioad, 1400rpm). implications will be discu ssed in details.