Reduction of Unburned Products in the Kerosene Vaporizing Burner by Using the Porcelain Tubes

Abstract

In the burner of small residential appliances, bluff bodies such as porcelain tubes and plates are often used in order to stabilize the flame and to purify exhaust gases.We studied the reduction mechanism concerning CO and UHC in the practical kerosene vaporizing burner, and also analized the flow mechanism around the bluff body by using the flow visualization technique with water.We have obtained the following results.(1) In the burner with two red heated porcelain tubes with diameter of 10mm, which was set 35mm above the flame port plate, CO and UHC have reduced to one half and one fifth respectively compared with the burner without using these tubes.(2) Residence time of flue gases in the recirculation zone behind the porcelain tubes is predicted to be sixty times as large as that without porcelain tubes.(3) From the information obtained through the flow visualization studies, the rela-tionship between 1R/d and Re reduces to 1R/d ∝√Re.(1R: length of recircula-tion zone, d: diameter of porcelain tube, Re: Reynolds number)(4) In the water flow model, secondary flow injections around the test body, which corresponds to the porcelain tube, make another recirculation zone near the combustion chamber wall. This recirculation zone is considered to be effec-tive to the mixing and purification characteristics.