Papers by Author: Bi Feng Yin

Abstract: Based on a diesel engine with common rail system, influence of EGR on combustion and emission characteristic were investigated. The test results show that EGR can cut down both cylinder pressure and the rate of pressure rise, which leads to the depression of instantaneous rate of heat release and combustion temperature and the extension of the whole combustion period.EGR make effective improvements on reducing NOx emissions in all the operating modes. In light load condition CO and HC emissions take a favorable turn with larger EGR rate, SOOT and fuel consumption are well maintained. In moderate and heavy load condition, the curve of HC ,CO emissions assume “hook-like”, which is get down first and then steep rise. SOOT is well maintained before the inflection point but get deteriorate after the point. As the working load rate of the engine become heavier, the rate of EGR whose inflection point located becomes smaller and the fuel consumption turn out to be worse.

Abstract: The objective of the literature is to investigate the influence of micro-arc grooves on the surfaces of the sliding tribopairs by plain pads to hydrodynamic lubrication. This is accomplished by the CFD-approach (computational fluid dynamic approach) where the momentum and continuity equations are solved separately, laminar model and SIMPLE algorithm in theory of Control Volume Method are adopted, and the rheology is assumed to be Newtonian. For various widths and depths of micro arc-grooves, the load supporting capacity of oil-film is calculated in the form of a net total force and static pressure, the friction is compared by the stress of smooth wall, and the dynamical pressure of the upper walls is shown. It will be found that width has more influences than depths to hydrodynamic lubrication, and relative parameters change monotonously with the depth of arc groove. Moreover, given primary film thickness as 6μm, within physically reasonable range of the parameters (depth and width of groove), i.e. in addition to w=40μm, hp=5μm~15μm, the effect of texturing arc-grooves on improvement of tribological properties will be conspicuous.

Abstract: Based on 1.9L small non-road diesel engine, mechanical and combustion system were redesigned and optimized to improve the emission performance. The engine block structure such as ribs, bolt hole depth and water jacket were optimized to improve the strength and stiffness and reduce the block’s distortion. The type of piston ring, piston skirt profile and their fit clearances were also optimized, and plat-honing cylinder liner was used to reduce the oil consumption. In combustion system, fuel injection pump, injection nozzle, fuel spray distribution and fuel supply advance angle were modified, combustion chamber was changed to small platform dumbbell-shaped chamber, and the closed-loop exhaust gas recirculation (EGR) system controlled by negative pressure was applied to trade-off the emissions of NOX and PM. The test results show that the emission performance of optimum diesel engine could meet EPA IV emission regulations.

Abstract: One new sliding-block balancing mechanism is proposed for the single-cylinder diesel engine. In the new mechanism, the sliding block is installed against the engine piston. The reciprocation trajectory of sliding block is collinear with the piston trajectory, while sliding block and piston move in the opposite direction, just like two opposite crank connecting rods. The new mechanism includes the crankshaft, connecting rod ring, the slider and the guide components. Through the bearing, connecting rod is installed in the eccentric journal of the crankshaft. The circular connecting rod is in the accurate guiding surface of the slider; and the guide pins are in the guide groove. Guide rod connects with supporting shaft through the guide hole of the slide. The optimized parameters for the sliding block show that the ratio of eccentric distance of the eccentric journal to the length of the connecting rod is equal to the ratio of crank radius to connecting rod length. The appropriate results can balance both the centrifugal inertia force and the reciprocating inertia force generated by piston group. Even the complete balance of the first and second-order reciprocating inertia forces can be obtained, which can reduce the vibration and noise of diesel engine.

Abstract: The bipolar plate is the key part in the fuel cell. It is difficult to produce the micro flow channel of bipolar plates with high accuracy. In order to solve this problem, we present one new forming techniques, accumulative forming, for the fabrication of micro flow channels. With the utilization of the software ABAQUS, finite element model of the bipolar plate with the 20mm×20mm×0.2mm is developed to simulate the accumulative forming and obtain the forming rules. The simulation results are about the plate’s thickness change and deformation. It shows that the thickness reduction decreases gradually from the center of the channel to the outside with the maximal magnitude in the starting point of accumulative forming. The maximum thinning ratio is 15.85%, which is in the forming limit scope. The simulation demonstrates the feasibility of the accumulative forming and good formability.