High-pressure Common-rail Engine Research Articles

Effect of different ammonia mixing methods for diesel ignition on combustion and emission performance of high pressure common rail engine

Ammonia is a zero-carbon fuel. Diesel/ammonia dual-fuel combustion mode can solve the problem of difficult compression ignition of pure ammonia. This article aims to explore the best mixing method and mixing ratio of ammonia fuel. The research results show that with the increase of the ammonia mixing ratio in the intake duct, the fuel consumption rate decreases by 7.71%. However, the serious ammonia escape phenomenon reaches a maximum of 37.35%, resulting in a serious decrease in power output. The cylinder temperature dropped by 197.12K, CO2 emissions decreased by 49.34%, NOx emissions decreased by 16.84%, and emissions significantly improved. When using direct injection ammonia mixing in the cylinder, as the ammonia mixing ratio increases, the explosion pressure in the cylinder decreases by 8.32%, the temperature in the cylinder decreases by 127.37K, the maximum ammonia escape is only 6.89%, CO2 emissions decreased by 88.10%, NOx emissions decrease by 75.90%, and CO2 and NOx emissions significantly decrease. Compared with the two ammonia blending methods, the direct injection ammonia blending method in the cylinder is obviously better. When the direct injection ammonia blending ratio in the cylinder is 70%, compared to the original engine, the diesel engine has the best working performance, increased power, and improved economy by 7.52%, and the proportion of ammonia escape is small. CO2 emissions are reduced by 69.05%, and NOx emissions are reduced by 29.22%. The research results of this article provide data support for achieving energy-saving, emission reduction, and low-carbon environmental protection of diesel engines.

Experimental study on in-cylinder combustion and exhaust emissions characteristics of natural gas/diesel dual-fuel engine with single injection and split injection strategies

On a non-road, high-pressure common-rail engine, natural gas/diesel dual-fuel (NDDF) combustion mode was performed. The way natural gas energy substitution percentage (ESP) and pilot diesel injection timing affected the combustion process, emission properties and fuel economy regarding NDDF engine with single injection strategy and split injection strategy was experimentally investigated at 25% load of 1800 rpm. Results show that under the two injection strategies, as ESP increased, NDDF combustion altered from single-stage to two-stage slowly, the combustion center (CA50) was delayed, the combustion duration increased, the soot and NO emissions declined, and the brake thermal efficiency (BTE) presented an increase-to-decrease change trend. As the combustion phase of split injection strategy was wholly advanced, the ignition delay period was shortened, the cyclic coefficient of variation (COV) and HC emission declined, and the BTE elevated. Additionally, the advanced injection timing would make NDDF heat release gradually advance, resulting in advanced CA50, extended ignition delay, lengthened combustion duration, lowered unregulated emissions, and increased BTE. The increase in peak heat release rate and BTE of split injection strategy was accompanied by decreased HC and aldehyde emissions. For NDDF engine possessing optimized split injection strategy, the BTE reached 37.79% and the COV reached 1.49% at ESP= 60%.

Influence of Ce-based catalytic fuel on exhaust particle physicochemical properties on a common-rail engine

ABSTRACTIn order to explore the changes of exhaust particulate matter (PM) with the addition of Ce-based catalyst in diesel, naphthenic acid cerium solution was selected as a fuel borne catalyst (FBC). According to Ce mass fraction of 50, 100, 150, and 300 mg/kg, the solutions were added to diesel fuel and marked as F50, F100, F150, and F300, respectively. The experiments were conducted on a four-cylinder high-pressure common-rail engine fueled with FBC fuel. The particle oxidation characteristics, soluble organic fraction (SOF) components, size distribution, and microstructure with FBC fuel were investigated. The results show that the oxidation reaction of PM shifted to the low-temperature area with increasing FBC blending ratio, and the optimum ratio of Ce element is 150 mg/kg. Compared with diesel particle sample, the number of high-carbon-atom in the SOF of FBC particles decreases and the polycyclic aromatic hydrocarbons (PAHs) decrease by 49.2%, shifting FBC particles to the smaller sizes. The peak number concentration of nucleation-mode particles increases by 8.9%, and the peak mass concentration decreases by 14.5%. The FBC particles contain Ce element mass fraction about 1.23%, and its morphology is loose and porous, besides the degree of bonding is significantly reduced.

Experimental investigation of particle emissions under different EGR ratios on a diesel engine fueled by blends of diesel/gasoline/n-butanol

The particle emission characteristics of a high-pressure common-rail engine under different EGR conditions were investigated, using pure diesel (D100), diesel/gasoline (with a volume ratio of 70:30, D70G30), diesel/n-butanol (with a volume ratio of 70:30, D70B30) and diesel/gasoline/n-butanol (with a volume ratio of 70:15:15, D70G15B15) for combustion. Our results show that, with increasing EGR ratios, the in-cylinder pressure peak decreases and the heat release is delayed for the combustion of each fuel. At an EGR ratio of 30%, the combustion pressure peaks of D70G30, D70B30, D70G15B15 and D100 have similar values; with an EGR ratio of 40%, the combustion pressure peaks and release rate peaks of D70G30 and D70G15B15 are both lower with respect to D100. For small and medium EGR ratios (⩽20%), after the addition of gasoline and/or n-butanol to the fuel, the total particle number concentration (TPNC) increases, while both the soot emissions and the average geometric size of particles decrease. At large EGR ratios (30% and 40%), the TPNC of D70B30, D70G15B15 and D70G20 compared to D100 are reduced by a maximum amount of 74.7%, 66.7% and 28.6%, respectively. As the EGR ratio increases, the total particle mass concentration increases gradually for all four fuels. Blending gasoline or/and n-butanol into diesel induces an increase in the number concentration of sub-25nm particles (PN25) which may be harmful in terms of health. However, the PN25 decreases with increasing the EGR ratio for all the tested fuels. At a fixed EGR ratio, the PN25 of D100 is the smallest, followed by D70G30, D70G15B15, and D70B30. However, the ratios of the mass concentration of sub-25nm particles to the total particle mass concentration are quite small, not exceeding 5%.

Noise Reduction of High-pressure Common-rail Engine and the Impact of the Engine Performances on the Noise

The noise of high-pressure common-rail engine and the impact of engine performances on the noise are studied. The overall noise of the prototype is measured and sound sources are identified through acoustic scan, and it is found that the front-end face, the intake side, the exhaust side and the top of the engine are the main sources of noise. So, clad steel plate is installed on the gear room, and the heat baffle of exhaust pipe and the thermal shroud of turbine shell all use noise reduction parts. These measures are very effective. Then the impact of economy and power performances of the engine on the noise is studied by adjusting the parameters of high-pressure common-rail system, and it is found that increasing the fuel consumption and reducing the torque can reduce the noise. Research results show that the engine performances have great influence on the engine noise, and the noise can be reduced at the expense of a certain percentage of economy and power performance.