A high performance flexible porous medium burner that can burn gaseous and liquid fuel with different type of flames （premixed and non-premixed） is proposed. The merit of the combustion within porous medium is that ...A high performance flexible porous medium burner that can burn gaseous and liquid fuel with different type of flames （premixed and non-premixed） is proposed. The merit of the combustion within porous medium is that heat is recirculated from the combustion gas to porous medium at upstream wherein vaporization is taken place （in case of liquid fuel） or preheated ~in case of gaseous fuel） before mixing with the combustion air followed by combustion within another porous medium at downstream. In a former version of the high performance flexible porous medium burner, the upstream porous medium is incorporated with a cooling system using the combustion air as a coolants to prevent thermal decomposition of fuels and thus the burner clogging caused by carbon deposit within the porous medium can be avoided. However, the cooling effect cannot be properly controlled such that the boiling point of the liquid fuel is maintained at suitable value irrespective of the volume flow rate of the combustion air, which is linearly varied with the firing rate of the burner. In particular at the lean burn condition, where high air flow rate is required with high cooling effect with porous medium. This can result in the porous medium temperature lower than the corresponding boiling point of the liquid fuel and thus evaporation of the fuel is failed and the combustion is ceased. Therefore, method of controlling the cooling air flow rate in the porous medium is proposed and studied in order to appropriately control the porous medium temperature and maintain it at above the boiling point irrespective of the combustion conditions. In this research, experimental and computation analysis are used to design the flexible porous burner （FPMB）, with adjustable cooling effect. The result shows that, the new design of FPMB which has temperature in the upstream porous medium is higher than boiling point and lower than thermal decomposition temperature of fuel （kerosene） at all conditions and can be operated at a wide range of equivalence ratio without fuel decomposition and fuel non-vaporization problem.展开更多
A numerical investigation of the different arrangements of porous media in a combustor with annular heat recirculation is conducted.The effect of annular heat recirculation and porous block arrangement on the characte...A numerical investigation of the different arrangements of porous media in a combustor with annular heat recirculation is conducted.The effect of annular heat recirculation and porous block arrangement on the characteristics of combustion wave propagation is numerically studied.Results show that power input,heat capacity of porous matrix,arrangement of porous blocks,and annular heat recirculation are major factors that influence the propagation of combustion wave.The overall temperature of ceramic porous burner is higher than that of ceramic-metal type burner due to the lower heat storage capacity of the former,especially for the temperature downstream.The flame temperature is higher upstream and lower downstream with metal foams in the annulus than that without metal foams.The flame temperature of uniformity type burner is more uniform than that of gradually-varied and modular type burners.The flame front moves more slowly with metal foams in the annulus than that without metal foams due to the better preheating effect of metal foams.The flame position moves downstream,and the flame temperature gradually decreases and is eventually extinguished due to the low preheating temperature.展开更多
A kind of ZrO2 ceramic material for porous media burner was prepared by polymeric sponge process with starting materials of zircon, zirconia powder, microsili- ca, and ball clay, and binder of silica sol through react...A kind of ZrO2 ceramic material for porous media burner was prepared by polymeric sponge process with starting materials of zircon, zirconia powder, microsili- ca, and ball clay, and binder of silica sol through reaction-sintering. The effects of microsilica addition on cold crushing strength and zirconia/zircon adding ratio on thermal shock resistance were studied. The results show that the porous media material has proper porosity, high strength, and excellent thermal shock resistance when zirconia addition is 85% and zircon addition is 5%. The performance indexes are： porosity 82%, cold crashing strength 3.1MPa, thermal shock resistance more than 10 cycles, and good thermal shock resistance to 1 500℃ flame.展开更多
文摘A high performance flexible porous medium burner that can burn gaseous and liquid fuel with different type of flames （premixed and non-premixed） is proposed. The merit of the combustion within porous medium is that heat is recirculated from the combustion gas to porous medium at upstream wherein vaporization is taken place （in case of liquid fuel） or preheated ~in case of gaseous fuel） before mixing with the combustion air followed by combustion within another porous medium at downstream. In a former version of the high performance flexible porous medium burner, the upstream porous medium is incorporated with a cooling system using the combustion air as a coolants to prevent thermal decomposition of fuels and thus the burner clogging caused by carbon deposit within the porous medium can be avoided. However, the cooling effect cannot be properly controlled such that the boiling point of the liquid fuel is maintained at suitable value irrespective of the volume flow rate of the combustion air, which is linearly varied with the firing rate of the burner. In particular at the lean burn condition, where high air flow rate is required with high cooling effect with porous medium. This can result in the porous medium temperature lower than the corresponding boiling point of the liquid fuel and thus evaporation of the fuel is failed and the combustion is ceased. Therefore, method of controlling the cooling air flow rate in the porous medium is proposed and studied in order to appropriately control the porous medium temperature and maintain it at above the boiling point irrespective of the combustion conditions. In this research, experimental and computation analysis are used to design the flexible porous burner （FPMB）, with adjustable cooling effect. The result shows that, the new design of FPMB which has temperature in the upstream porous medium is higher than boiling point and lower than thermal decomposition temperature of fuel （kerosene） at all conditions and can be operated at a wide range of equivalence ratio without fuel decomposition and fuel non-vaporization problem.
基金supported by the National Key R&D Program of China (2018YFB0605904)
文摘A numerical investigation of the different arrangements of porous media in a combustor with annular heat recirculation is conducted.The effect of annular heat recirculation and porous block arrangement on the characteristics of combustion wave propagation is numerically studied.Results show that power input,heat capacity of porous matrix,arrangement of porous blocks,and annular heat recirculation are major factors that influence the propagation of combustion wave.The overall temperature of ceramic porous burner is higher than that of ceramic-metal type burner due to the lower heat storage capacity of the former,especially for the temperature downstream.The flame temperature is higher upstream and lower downstream with metal foams in the annulus than that without metal foams.The flame temperature of uniformity type burner is more uniform than that of gradually-varied and modular type burners.The flame front moves more slowly with metal foams in the annulus than that without metal foams due to the better preheating effect of metal foams.The flame position moves downstream,and the flame temperature gradually decreases and is eventually extinguished due to the low preheating temperature.
文摘A kind of ZrO2 ceramic material for porous media burner was prepared by polymeric sponge process with starting materials of zircon, zirconia powder, microsili- ca, and ball clay, and binder of silica sol through reaction-sintering. The effects of microsilica addition on cold crushing strength and zirconia/zircon adding ratio on thermal shock resistance were studied. The results show that the porous media material has proper porosity, high strength, and excellent thermal shock resistance when zirconia addition is 85% and zircon addition is 5%. The performance indexes are： porosity 82%, cold crashing strength 3.1MPa, thermal shock resistance more than 10 cycles, and good thermal shock resistance to 1 500℃ flame.
