Applied Mechanics and Materials Vols. 316-317

Abstract: The fuel usually has high viscosity and low quality for marine diesel engines. Especially for its shallow combustion chamber structures, the preparation of in-cylinder mixture gas is mainly rely on spray and atomization, which is vulnerable influenced by fuel viscosity and surface tension seriously. Based on the case, this paper introduced a CFD method to heat the diesel fuel to reduce fuel viscosity and surface tension, expecting to explore the in-cylinder combustion process and emissions generation, so that the atomization effect of fuel spray and combustion in diesel could be improved. The calculation model was set up according to the L23/30H diesel engine. Temperature field and pressure field in cylinder were calculated and the emission of NO were studied under conditions of different fuel temperatures. The results show that the increasing of fuel temperature is helpful to realize low-temperature combustion and reduce NO emission to some extent.

Abstract: In this paper, on-board Measurements of particle emissions were carried out on a VW diesel car in Shanghai real roads. The test fuels included pure petroleum diesel (D100) and three different alternative fuel blends, 10% biodiesel blend (BD10), 10% coal-to-liquid fuel blend (C10) and 10% gas-to-liquid fuel blend (G10) in volumetric mixture ratio. Results showed that particle emissions in freeways were terrible, and particle number emission ratios from urban roads were high. The test alternative blend fuels of BD10, Bu10, G10 and C10 all have positive effects on the particle emissions of test diesel car.

Abstract: Particle emissions of a diesel car fueled with coal to liquids (CTL) on road were tested. The particle number and size distribution were mainly studied. Three typical roads were adopted in this test, including urban arterial roads, secondary roads and freeways. The results show that transient particle number of the car has a corresponding relationship with the vehicle speed. With the speed increasing, the number of both nucleation mode particles and accumulation mode particles increase continuously. With the CTL blend ratio increasing, the number of nucleation mode particles and accumulation mode particles decreases, especially accumulation mode particles whose size are more than 100nm diameter. With the CTL blend ratio increasing, the particle numbers in the three typical roads show downward trends, especially on freeways. It shows that the CTL fuel can distinctly reduce the exhaust particle number of diesel cars on road.

Abstract: With the use of the Engine Exhaust Particle Sizer (EEPS) developed by TSI, particle size distribution characteristics of China-IV diesel bus fueled biodiesel are studied under real operating condition. Four mixtures of volume ratio between restaurant waste oil and China-IV diesel 5%, 10%, 20%, 50% respectively (marked separately by BD5, BD10, BD20, BD50), pure biodiesel (BD100) and pure diesel (BD0) were tested. The results indicated that the average velocity of diesel bus is 18km/h. Of the entire operating time, idle operating period accounts for 30%, low and medium velocity 58%, and acceleration and deceleration 89%. In different velocity ranges, the size distribution of particulate number emissions (PNSD) is bimodal; in different acceleration ranges, PNSD shows a gradual transition from bimodal shape to unimodal when bus operation switches from decelerating to accelerating status. Biodiesel blended with higher mixture ratios show significant reduction in PN emissions for accumulated modes, and particulate number emission peaks move towards smaller sizes; but little change was obtained in PN emissions for nuclei modes with its particulate size of peak sustains around 10nm.

Abstract: Open-loop control strategy of SCR urea injection system for MD/HD vehicle diesel engine is established firstly in this paper. Then the emission test is performed for a domestic diesel engine in test bench. Test results show that NO_X emissions of ESC and ETC are much lower than the limit values of National-IV emission regulation under a simple injection strategy. The results also show that the urea solution consumption accounts for only 5.8% of the fuel consumption. What’s more, the tests have been accumulated for achieving accurate matching between urea injection and diesel engine.