Abstract
Effects of the fuel partition between the rich and the lean flames and the air ratios of the lean and the rich flames on the characteristics of the rich-lean combustion under low-load condition were investigated in order to develop a new type of a domestic boiling water heater and a warm heater with low emission of NOx, high TDR and high thermal efficiency. It is clarified from the results of the analysis of the burned gas, the thermal efficiencies and the temperatures of the burner plates that the optimum conditions under low-load combustion are X_R:X_L=30:70 for the fuel partition between the rich and the lean flames and around λ_L=1.46 and λ_R=0.49 for the air ratios of the lean and the rich flames, respectively.