The effects of supply temperature and vertical location of inlet air on particle dispersion in a displacement ventilated （DV） room were numerically modeled with validation by experimental data from the literature. T...The effects of supply temperature and vertical location of inlet air on particle dispersion in a displacement ventilated （DV） room were numerically modeled with validation by experimental data from the literature. The results indicate that the temperature and vertical location of inlet supply air did not greatly affect the air distribution in the upper parts of a DV room, but could significantly influence the airflow pattern in the lower parts of the room, thus affecting the indoor air quality with contaminant sources located at the lower level, such as particles from working activities in an office. The numerical results also show that the inlet location would slightly influence the relative ventilation efficiency for the same air supply volume, but particle concentration in the breathing zone would be slightly lower with a low horizontal wall slot than a rectangular diffuser. Comparison of the results for two different supply temperatures in a DV room shows that, although lower supply temperature means less incoming air volume, since the indoor flow is mainly driven by buoyancy, lower supply temperature air could more efficiently remove passive sources （such as particles released from work activities in an office）. However, in the breathing zone it gives higher concentration as compared to higher supply air temperature. To obtain good indoor air quality, low supply air temperature should be avoided because concentration in the breathing zone has a stronger and more direct impact on human health.展开更多
Combustion characteristics of methane jet flames in an industrial burner working in high temperature combustion regime were investigated experimentally and numerically to clarify the effects of swirling high temperatu...Combustion characteristics of methane jet flames in an industrial burner working in high temperature combustion regime were investigated experimentally and numerically to clarify the effects of swirling high temperature air on combustion.Speziale-Sarkar-Gatski(SSG) Reynolds stress model,Eddy-Dissipation Model(EDM),Discrete Ordinates Method(DTM) combined with Weighted-Sum-of-Grey Gases Model(WSGG) were employed for the numerical simulation.Both Thermal-NO and Prompt-NO mechanism were considered to evaluate the NO formation.Temperature distribution,NO emissions by experiment and computation in swirling and non-swirling patterns show combustion characteristics of methane jet flames are totally different.Non-swirling high temperature air made high NO formation while significant NO prohibition were achieved by swirling high temperature air.Furthermore,velocity fields,dimensionless major species mole fraction distributions and Thermal-NO molar reaction rate profiles by computation interpret an inner exhaust gas recirculation formed in the combustion zone in swirling case.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 40975093)Shanghai Educational Development Foundation titled "Shuguang Project", P.R. China(Grant No. 03SG30)
文摘The effects of supply temperature and vertical location of inlet air on particle dispersion in a displacement ventilated （DV） room were numerically modeled with validation by experimental data from the literature. The results indicate that the temperature and vertical location of inlet supply air did not greatly affect the air distribution in the upper parts of a DV room, but could significantly influence the airflow pattern in the lower parts of the room, thus affecting the indoor air quality with contaminant sources located at the lower level, such as particles from working activities in an office. The numerical results also show that the inlet location would slightly influence the relative ventilation efficiency for the same air supply volume, but particle concentration in the breathing zone would be slightly lower with a low horizontal wall slot than a rectangular diffuser. Comparison of the results for two different supply temperatures in a DV room shows that, although lower supply temperature means less incoming air volume, since the indoor flow is mainly driven by buoyancy, lower supply temperature air could more efficiently remove passive sources （such as particles released from work activities in an office）. However, in the breathing zone it gives higher concentration as compared to higher supply air temperature. To obtain good indoor air quality, low supply air temperature should be avoided because concentration in the breathing zone has a stronger and more direct impact on human health.
文摘Combustion characteristics of methane jet flames in an industrial burner working in high temperature combustion regime were investigated experimentally and numerically to clarify the effects of swirling high temperature air on combustion.Speziale-Sarkar-Gatski(SSG) Reynolds stress model,Eddy-Dissipation Model(EDM),Discrete Ordinates Method(DTM) combined with Weighted-Sum-of-Grey Gases Model(WSGG) were employed for the numerical simulation.Both Thermal-NO and Prompt-NO mechanism were considered to evaluate the NO formation.Temperature distribution,NO emissions by experiment and computation in swirling and non-swirling patterns show combustion characteristics of methane jet flames are totally different.Non-swirling high temperature air made high NO formation while significant NO prohibition were achieved by swirling high temperature air.Furthermore,velocity fields,dimensionless major species mole fraction distributions and Thermal-NO molar reaction rate profiles by computation interpret an inner exhaust gas recirculation formed in the combustion zone in swirling case.
