Abstract
Conventional compression ignition engines can easily be converted to a dual fuel mode of operation using natural gas as main fuel and diesel oil injection as pilot to initiate the combustion. At the same time, it is possible to increase the output power by increasing the diesel oil percentage. A detailed performance and combustion characteristic analysis of a heavy duty diesel engine has been studied in dual fuel mode of operation where natural gas is used as the main fuel and diesel oil as pilot. The influence of intake pressure and temperature on knock occurrence and the effects of initial swirl ratio on heat release rate, temperature-pressure and emission levels have been investigated in this study. It is shown that an increase in the initial swirl ratio lengthens the delay period for auto-ignition and extends the combustion period while it reduces NOx. There is an optimum value of the initial swirl ratio for a certain mixture intake temperature and pressure conditions that can achieve high thermal efficiency and low NOxemissions while decreases the tendency to knock. Simultaneous increase of intake pressure and initial swirl ratio could be the solution to power loss and knock in dual fuel engine.
Highlights
Natural gas, because of cleaner nature of its combustion and lower price compared with conventional liquid fuels, is the most attractive and widely accepted among alternative gaseous fuels
Pirouzpanah and Kashani predicted the major pollutants in a direct injection dual fuel engine using a multi-zone model for pilot and two-zone model for gaseous fuel [4]
Detailed and reduced chemical kinetics reaction mechanisms have been introduced in CFD programs to give accurate prediction of combustion in an engine running on dual fuel mode of operation
Summary
Because of cleaner nature of its combustion and lower price compared with conventional liquid fuels, is the most attractive and widely accepted among alternative gaseous fuels. Karim simulated autoignition and knock in dual fuel engine using a two-zone model and detailed chemical kinetics including 14 species and 32 reactions [2]. Detailed and reduced chemical kinetics reaction mechanisms have been introduced in CFD programs to give accurate prediction of combustion in an engine running on dual fuel mode of operation. Further numerical study of dual fuel engine combustion and emission was done by Kusaka et al [12] and computational CFD modeling of dual fuel (gas/diesel) was carried out by Zhang et al, [13]. A reduced detailed chemical kinetics mechanism with 79 species and 292 reactions is considered to predict oxidation of fuels and knock in the dual fuel mode of operation
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