الفهرس 
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Abstract
The devolpment of gas fuelled dual fuel compression igition engines provides an alternative approach for internal combustin engines to improve economy, reduce exhaust emissions and achieve greater power output.
Dual fuel operation of a single cylinder, indirect injection diesel engine (Ricardo E6) can yield ahigh thermal eficiency almost comparable to the diesl operation at higher loads. The dual fuel operation at lower loads, however, inevitably suffers from lower thermal efficiencey and higher unburned percentages of fuel.
To improve this problem, engine test were carried out on a variety of engine parameters including the type and concentration of gaseous fuel, quantity of diesel fuel injected (pilot), inhection timing of pilot fuel , intake temperature, diluent admissions and exhaust gas recirculation (EGR) .
On the hand, the present work included a computational part to predict the performance of dual fuel operation by developing and using two detailed chemical kinetic schemes and a quasi-two zone analytical model. The comprehensive chemical kinetic scheme for methane oxidation consisting of 178 elemntary reaction steps with 41 species. Sensitivity analysis carried out to simplify the comperehisive chemial kinetic scheme to another scheme of 40 elementary reation steps with 17 species in order to reduce the coputational time from 72 to hours for each run of the program. The quasi-two zone analytical model develop is based on the effective energy releases of pilot diesel fuel whil using the detsiled chemical reaction kinetic sccheme for the oxidation of methane. Through the experimental and computational investigation, it is shown that, the low efficiency and poor emissions at light loads can be improved sigificantly by increasing the concentration of the gaseous fuel total equivalence ratio, employing a large pilot fuel, increasing the intake temperancing the injection timing of pilot fuel, increasing the intake temerature and by using the exhaust gas recirculation (EGR).
On the other hand, at high loads with methane as fuel , efficiency and exhaust emissions, particularly Nox are improved only by using exhaust emissions, exceot Nox.
The use of EGR is considered to be the best means to improve the operation of diesel engine fuelled espeially with methane. Maximum limit of EGR ratio is found around 50% .An additional contrebution is the improvement of the available emprical relation of heat release rate from pure disel in the prsence of EGR.