Study On The Physical And Chemical Properties Of Heavy Oil With Dimethyl Ether And Its Emission Characteristic

With the development of economy and our society,the total volume of international trade isincreasing rapidly,which brings the prosperity of shipping industry.Heavy oil has become the mainfuel of marine medium and low speed diesel engine because of its cheap price.However,heavy oilwill do great damage to the environment with its high viscosity,lower heating value,higher sulfuramount and poor combustion characteristic.It is very important for us to look for a new kind ofalternativefuelso that wecan useclean energy andprotect ourenvironment.As an alternative fuel,dimethyl ether has attracted great attention in these years.DME hasmany merits such as easily compressed,quickly condensated and easily dissolved with other polaror nonpolar fuel.However,because of its low viscosity and great corrosive property,it will dodamage to diesel engine system couples. The paper intends to make a contrast between heavy oiland other regular alternative fuels,and then find the best remedy to each other.Through mutualsolubility theory and thermodynamic model analysis,we can study the combustion and emissioncharacteristics further.In this way,DME’s good combustion merit and lower dynamic viscosity canmake up for heavy oil bad combustion characteristic,which will lead to saving energy anddecreasingemission.The paper intends to study on the mutual solubility theory of DME with heavy oil and itsemission characteristics by theory and experiment.We calculated the solubility parameter andanalyzed thermodynamic model,and then found that the solubility parameter deviation of blendedfuel is0.68~1.1,which is so litter that DME and heavy can dissolve easily.Meanwhile,AddingDME to the heavy oil with high dynamic viscosity will dramatically decrease the viscosity of themixed oil,making up the demerit of heavy oil and DME,too.The blended fuel with45%DMEcompared with180cSt/50℃heavy oil,the viscosity averagely decreases73.27％.H75D25,H55D45and120cSt pure heavy oil have been experimented in the diesel engine without adjusting theYC6A220C diesel engine’s parameters,choosing speed at1200rpm,1400rpm and1600rpm asworking condition, load setted as20％，40％、60％、80％and100％.The result showedthat,compared with pure heavy oil,blended fuel has a good performance on combustion andemission.Heat release and heat release rate increases and ignition delay period decrease with theratio of DME in the blended oil.In the terms of emission HC,CO and Soot emission decreasesdramatically,even more with highDME ratio.CO,HC and soot emission decreases57.6％,76.84％and57.85％,but NOx will increase28.87％when the load is low.