Characteristics Of Combustion And Emission In LNG Reformed Gas/Diesel Dual-Fuel Internal Combustion Engine

To further enhance characteristics of combustion and emission of marine diesel engine, and to set the advantage of marine diesel engine power, LNG eco-fridendly and LNG reformed gas heat of combustion higher than LNG, so LNG reformed gas/diesel dual fuel engines was got research.Firstly, using n-heptane/ toluene as some alternatives to diesel fuel for simulation, and building reaction mechanism of LNG reformed gas/diesel includes NO_X formation mechanism. Secondly, by using HSC, steam reforming methane reaction was analyzed under various temperatures, pressures, steam carbon ratio?H2O/CO2?, and preparation of the LNG reformed gas was realized. Additionly, by using CHEMKIN-PRO, that dual-fuel engine in-cylinder temperature and pressure and the pollutants effects of NO_X and CO was studied, under various parameters of substitution rates, intake temperature, intake pressure, equivalent ratio, speed, EGR rate and compression ratio. Finally, internal combustion engine efficiency of heat engine, indicating power and fuel consumption of CH₄ was analyzed of LNG reformed gas/diesel mixed fuel. Results show that:?1? Adding toluene in n-heptane can better simulate diesel.?2? To better simulate burning process, the effectiveness of building mechanisms was verified.?3? In the steam reforming methane reaction, conversion rate of methane increase at high temperature and low pressure, and conversion rate of methane increase under high steam and carbon ratio but increased water vapor. When T=700?, P=1 atm and steam carbon ratio K=3, methane has a conversion rate of 96.99%, calorific value of methane increased by 22.48%, and under the same heat, 18.35% reduced in combustion CH₄ consumption.?4? Promoting reaction?R23? can reduce CO emission; promote reaction?R464? and response reaction?R466? can reduce NO emissions.?5? Accompanying alternative rate and speed increase, in-cylinder temperature and pressure increased, and NOx, CO emissions reduced; Accompanying intake temperature and equivalent ratio increase, in-cylinder temperature and pressure increase, and NO_X and CO emissions increase; Accompanying intake pressure and compression ratio increase, temperature, and pressure increase, and CO emissions reduced, but NO_X emissions increase; Higher EGR rate can be effective in reducing NO_X emissions, but that has some negative effects in the in-cylinder temperature and pressure and the discharge.?6? Accompanying alternative rate increase, that efficiency of heat engine and indicates power is reduced; Accompanying equivalent ratio increase, the 80% of alternative rate is best; Accompanying equivalent ratio reduce, lowering the combustion CH₄ consumption under the same heat.