The influence of burner material properties on the acoustical transfer function of radiant surface burners

Modern central heating systems use low NO_x premixed burners with a large modulation range, which can lead to noise problems. A large class of burners currently used in boiler equipment is formed by radiant surface burners. These burners are generally made of a porous material on which (nearly) at flame can be stabilized. This will lead to heat transfer from the flame to the burner, and consequently a cooler flame and reduced NO_x emissions. A detailed model for the heat transfer between the gas and the burner was used to numerically study the influence of several different material properties on the acoustical transfer coefficient. The model was tested with measurements of the transfer function for four different burner deck types with known material properties. An accurate description of the heat transfer in the porous material was essential for a good modeling of the acoustical transfer function. This is an abstract of a paper presented at the 30th International Symposium on Combustion (Chicago, IL 7/25-30/2004).