Wide Open Throttle Operation Research Articles

Effect of flash boiling on microscopic and macroscopic spray characteristics in optical GDI engine

The flash boiling sprays in a single-cylinder optical gasoline direct injection (GDI) engine were studied using phase Doppler particle analyzer (PDPA) and high-speed photography. Initially, the factors which may influence the in-cylinder measurement reliability of PDPA were carefully examined under atmospheric conditions. Afterwards, engine experiments were conducted under idle and wide open throttle (WOT) conditions with the fuel temperature ranging from 20°C to 90°C. The results show that under idle operation, the spray collapsed towards the injector axis as the fuel temperature increased. At high fuel temperatures, the spray penetration increased so that the probability of fuel-wall impingement rises. As the fuel temperature increased from 20°C to 60°C, the AMD and SMD slumped by 43.6% and 33.2%, indicating the dramatic improvement in atomization quality. Concurrently, the droplet uniformity decreased sharply. As the temperature further increased to 90°C, the AMD and SMD only dropped slightly, but the droplet uniformity became better. Under WOT operation, no distinct evidence of spray deformation was found except for the case at 90°C. The AMD and SMD dropped steadily with the increase in fuel temperature, which is mainly attributed to the reduction in viscosity and surface tension. Besides, the droplet uniformity increased gradually along with the fuel temperature.

Experimental Investigation on the Emissions of a Port Fuel Injection Spark Ignition Engine Fueled with Methanol–Gasoline Blends

The prospect of using methanol as an alternative fuel for vehicles in China is enticing because of its good combustion properties, low production cost, and renewable capacity, but the in-cylinder combustion of methanol also brings extra emissions concerns, such as alcohols and aldehydes. For the impact of methanol–gasoline blends on the pollutant emissions of spark ignition (SI) engines to be investigated, a GEELY MR479Q port fuel injection SI engine was selected for tests of burning different methanol–gasoline blends at wide-open throttle operating conditions, and an AVL Fourier-transform infrared multicomponent gas analyzer was used to measure all of the emissions. Test results show that the methanol-containing fuel blends had positive effects on the engine-out regulated emissions. Nitrogen oxide, carbon monoxide, and nonmethane hydrocarbon emissions were all dramatically reduced when the test engine was fueled with methanol–gasoline blends. Other hydrocarbon emissions such as ethylene, propylene, and s...

HCNG 엔진의 터보차저 변경에 따른 전부하 출력 및 배출가스 특성 연구

Hydrogen-natural gas blends(HCNG) engine is optimizing technology of performance and emission characteristics with use of hydrogen's fast flame speed and wide flammability limit. As lean-burn limit is extended, the improvement in thermal efficiency and harmful emissions can be achieved. However, the extension of lean-burn limit under a wide open throttle operation point could be realized with the increase in boosting capacity in a lean-burn engine with turbo-charging system. In the present study, the power output characteristics of HCNG engine with turbo-charger change is assessed and feasibility of the increase in boost- ing capacity is evaluated. The turbo-charger design with high efficiency at higher flow rate rather than higher boosting pressure makes efficient operation possible at relatively rich mixture condition.

Effect of mixer type on cylinder-to-cylinder variation and performance in hydrogen-natural gas blend fuel engine

Compressed natural gas (CNG) buses were adopted in urban areas as a promising alternative to diesel buses, which emitted plenty of harmful emissions. Although CNG can meet the current emission standards, satisfying the requirements of the next EURO-VI emission regulation without an additional peripheral device may be impossible. The use of a hydrogen-compressed natural gas (HCNG) blend can help achieve a reduction in automotive exhaust emissions as well as prepare for an upcoming hydrogen economy through the construction of hydrogen infrastructure. Moreover, an HCNG engine has higher thermal efficiency than a CNG engine, producing lesser harmful emissions.Cylinder-to-cylinder variation affects multicylinder engine operation and can considerably influence an HCNG engine because fuel composition and excess air ratio differences can contribute to cylinder-to-cylinder variations. In the present study, the effect of the mixer type on cylinder-to-cylinder variation and performance characteristics were investigated using an 11-L heavy-duty CNG engine fuelled with HCNG (CNG 70 vol%, hydrogen 30 vol%). A change in the mixer type does not affect the characteristics of cylinder-to-cylinder variation and the combustion stability of the HCNG engine. The efficiency of cylinders 1 and 6 is lower than that of the other cylinders because of the configuration of the cylinder in the in-line-type engine. The significant increase in the pressure drop under a wide open-throttle operating condition makes it difficult to satisfy the engine's specifications.

The influence of inter-ring pressures on piston-ring/liner tribological conjunction

The article proposes a mathematical model, which predicts the frictional performance of an internal combustion engine compression ring in the vicinity of the top dead center region. It accounts for the blow-by induced inter-ring pressures drop and for the cavitation region at the trailing edge of the contact. The model is used to predict the behaviour of both new and worn compression rings for wide open throttle operating conditions. It is shown that the wear of the ring profile increases the oil film thickness decrease the frictional losses and significantly reduces the extent of the cavitation region.

Performance and emission characteristics of a turbocharged spark-ignition hydrogen-enriched compressed natural gas engine under wide open throttle operating conditions

This paper investigates the effect of various hydrogen ratios in HCNG (hydrogen-enriched compressed natural gas) fuels on performance and emission characteristics at wide open throttle operating conditions using a turbocharged spark-ignition natural gas engine. The experimental data was taken at hydrogen fractions of 0%, 30% and 55% by volume and was conducted under different excess air ratio ( λ) at MBT operating conditions. It is found that under various λ, the addition of hydrogen can significantly reduce CO, CH 4 emissions and the NO x emission remain at an acceptable level when ignition timing is optimized. Using the same excess air ratio, as more hydrogen is added the power, exhaust temperatures and max cylinder pressure decrease slowly until the mixture’s lower heating value remains unchanged with the hydrogen enrichment, then they rise gradually. In addition, the early flame development period and the flame propagation duration are both shorter, and the indicated thermal efficiency and maximum heat release rate both increase with more hydrogen addition.