The Optimal Design of DME Injection for NOx Reduction of the DME Dual Diesel (DDF/DME) Engine on a Heavy Duty Truck

Abstract

Introducing DME gas into the combustion air intake of a engine acts as an accelerant, promoting more complete combustion, and resulting 27.3% NOx emission reduction has been achieved using the DDF/DME control system. The ESC 13 Mode tests of a Mitsubishi 7545 c.c., 6‐cyl. Diesel engine with a DDF/DME system are conducted. The optimal amount of the DME injection into each cylinder of the Diesel engine for NOx reduction purpose is derived as function of the boost pressure at the manifold. Experimental results show that the boost pressure is linear to the engine rpm for 50% load of DDF/DME engine. This line is parallel to the boost pressure – engine rpm line for 50% load of DDF/LPG engine. A boost pressure oriented LPG injection controller has been developed to revamp on the Diesel engine of a 15‐ton Taipei City refuse truck. The DDF/LPG heavy duty truck has been running 8 months with 18% fuel saving rate and 32% smoke reduction rate. The boost pressure oriented DME injection controller for NOx reduction purpose is being fabricated and tested on the same heavy duty refuse truck. The average substitution of DME to Diesel is 27.5 % by mass fraction. The cost of DDF/DME system is only 5,000 USD per set. An efficient DDF/DME system is important to the reduction of the NOx emissions of the 120,000 Euro II and Euro III standard heavy duty trucks and the set‐up of DME for transportation fuel industry in future Taiwan.