Search Results

We developed a numerical method for PFI engine, which would take complex intake-port phenomena into consideration. Numerical study for PFI engine has additional difficulty compared with that for GDI engine, because in-cylinder distribution of mixture is strongly affected by remaining fuel in intake-port. The new simulation method proposed in this paper has adopted split calculation of two steps. Fuel distribution in intake-port is calculated in the first step, and then this result of adhered and floating fuel distribution in intake-port is used as boundary and initial conditions in the next step. Together these two steps realize accurate in-cylinder mixture distribution prediction. According to experimental verification, the new method showed a capability to predict accurate liquid film distribution with less calculation cost. And then we applied the method into the investigation for optimum injection strategy to improve engine performance and to reduce emission.

Making use of fabric filtration in diesel particulate collection, a multi-bag particulate collection system for diesel buses was developed. Teats of the particulate collector prototype on a diesel engine dynamometer bench and an operating diesel bus showed that the collection system worked reliably with particulate collecting efficiency more than 90%.Further developmental work on the collection system is suggested.

A ceramic foam particulate trap for reducing automotive diesel engine particulate emission was developed. With its trapping efficiency 50-70 %, the trap is also reliable and durable. However, under practical automotive cruising conditions with exhaust temperature 400-650 K, particulates deposited in trap element cannot be burned up spontaneously to regenerate the element. The thermal regeneration temperature is 750-800 K. Adding organic compounds of copper, cerium or other metals in diesel fuel in concentrations 0.1-0.2 g/L (on the effective metal ion basis) reduces the regeneration temperature by about 100 K which is not enough to make the trap regenerate reliably in practical automotive application of particulate trap. A Simple diesel fuel burner developed regenerated the ceramic element completely in 1-3 minutes, providing a promising future for the practical utilization of the diesel particulate trap.

The paper consists of two parts. In the first part reported are the results of experimental physical characterization of a light duty IDI diesel engine exhaust particulate: concentrations, size distributions, and morphology. In the second part of the paper, presented is the development of a prototype particulate trap-oxidizer with ceramic foam as trapping element to reduce light-duty vehicle diesel engine exhaust particulate emission level. Tests of the trap-oxidiaer on the 485% diesel engine showed, ceramic foam trap reduced the diesel particulate emissions by 50-70% on the basis of mass concentrations. Trapped particulate deposits incinerates spontaneously when exhaust gas temperature over 450°C, reducing the resistance of the trap to exhaust flow. By the aid of fuel additives the regeneration temperature may he lowered by about 100°C.