1. Diagram of experimental system Effect of surrounding temperature on Direct images of DME diffusion flame 293 K 700 K 900 K 1100 K Left Total soot volumes with various O 2 concentrations (fuel:DME,Methane) Right Total soot volumes of methane(upper) and DME(lower) at various hight of flame (1000K) Flame Behavior and soot formation of in high temperature and low oxygen ambient condition,34th Graduation research symposium Hokkaido branch JSME, collected papers p.165-166(2005) Investigation of the condition and the mechanism of soot formation on DME flame,44th symposium Hokkaido branch JSME (2005) Soot formation of DME flame in high temperature ambient condition,35th Graduation research symposium Hokkaido branch JSME, collected papers p.266-267(2006) Publications Background and objective DME, oxygen-contain fuel yields very few soot during their combustion process. Therefore, the brightness of the DME flame is darker than that of the heavy oil, and intensity of radiative heat transfer from the flame becomes lower. The decrease of radiation may causes the decrement of performance for some kind of existing boilers. The objective of this research is to investigate the key parameter for soot production in DME flames, and it enhances application capability of DME to be a substitution of heavy oil in the commercial boilers. Background and objective DME, oxygen-contain fuel yields very few soot during their combustion process. Therefore, the brightness of the DME flame is darker than that of the heavy oil, and intensity of radiative heat transfer from the flame becomes lower. The decrease of radiation may causes the decrement of performance for some kind of existing boilers. The objective of this research is to investigate the key parameter for soot production in DME flames, and it enhances application capability of DME to be a substitution of heavy oil in the commercial boilers. Result of research Experimental study of soot formation on DME flame was performed under various surrounding temperature and oxygen concentration. Amount of soot in the diffusion flames were measured by the transmitted light attenuation method, and generated soot volume fraction for DME flames is compared to that for methane flames. Soot production on DME flame was observed in high surrounding temperature, and amount of soot was less than that of methane flame at same temperature and oxygen concentration. Soot amount shows a peak at particular concentration of oxygen, and this trend is held in various preheated temperature. The peak position of soot volume factor in the flame moves to the downstream with an increase of oxygen concentration. Compare to methane flame, peak position in DME flame tend to appear at the downstream with same oxygen concentrations. This fact implies the differences of soot formation mechanism between DME and methane. Result of research Experimental study of soot formation on DME flame was performed under various surrounding temperature and oxygen concentration. Amount of soot in the diffusion flames were measured by the transmitted light attenuation method, and generated soot volume fraction for DME flames is compared to that for methane flames. Soot production on DME flame was observed in high surrounding temperature, and amount of soot was less than that of methane flame at same temperature and oxygen concentration. Soot amount shows a peak at particular concentration of oxygen, and this trend is held in various preheated temperature. The peak position of soot volume factor in the flame moves to the downstream with an increase of oxygen concentration. Compare to methane flame, peak position in DME flame tend to appear at the downstream with same oxygen concentrations. This fact implies the differences of soot formation mechanism between DME and methane.