Investigation on partially premixed combustion fueled with gasoline and PODE blends in a multi-cylinder heavy-duty diesel engine

Gasoline partially premixed combustion (PPC) has been reported as an advancing concept for high efficient and clean combustion, while there still remains some obstacles. In this study, polyoxymethylene dimethyl ethers (PODE), which has superior properties of high oxygen content, high cetane number and no C-C bond, is employed as an additive to optimize the properties of gasoline and solve the problems faced in gasoline PPC. The effects of gasoline/PODE blends with PODE volume blending ratio of 0, 10% and 20% on combustion and emission have been investigated from low to high loads in a multi cylinder heavy-duty diesel engine. The experimental results show that the soot emission can be maximally reduced by 79% and 94% at high load when fueling PODE 10 and PODE20, respectively. The NOx-soot trade off relationship can be dramatically improved without penalty of fuel economy by fueling gasoline/PODE blends. The raw NOx and soot emissions can meet Euro V standards at high load and Euro VI standards at medium load by fueling both PODE10 and PODE20. Furthermore, the pressure rise rate can be maximally reduced by 24% and 47% when fueling PODE1 0 and PODE20. At medium load, the combustion controllability and sensitivity can be improved by gasoline/PODE blends. At low load, the COVIMEP can be reduced to 2.7% by fueling PODE20 which means a stable combustion can be obtained. Furthermore, the combustion efficiency can be dramatically improved from 85.1% to 99.6% by fueling PODE20, which leads to lower HC and CO emissions. Overall, PODE shows great advantage in solving the obstacles faced in gasoline PPC. (C) 2016 Elsevier Ltd. All rights reserved.