A review of the effect of particulate traps on the efficiency of vehicle diesel engines

Abstract

Particulate traps are becoming more widely used on city buses, some delivery trucks and fork lift trucks. The possible use of diesel particulate traps will lead to a fuel consumption penalty imposed on the baseline engine that is due to the trap back pressure as well as to the energy requirements of the regeneration technique adopted to incinerate the collected soot at will. The combined effect of trap back pressure imposed on the engine and additional energy required for trap regeneration on the overall efficiency of the diesel power plant is examined in this paper. This effect varies according to engine type, trap type and size, regeneration system used, and the vehicle driving mode. Because of the strong interaction among the above parameters, optimization of trap systems on efficiency grounds is complicated. This complexity is even more pronounced in the case of diesel-powered passenger cars, where the full exploitation of their efficiency advantage over gasoline-powered cars is constrained by the necessity of an optimized solution of the particulate emission problem. The main diesel particulate trap regeneration philosophies existing today are reviewed in terms of their effect on the total efficiency of the diesel power plant. This is done by means of representative examples, concerning systems which may be suitable for large-scale application. The conclusions indicate that the price that must be paid for environmental protection, in the case of diesel particulate control systems, may be substantially reduced by system design optimization.