LAUSR

Abstract This work aimed to evaluate the effects of C 2 H 6 , C 2 H 4 , CO, H 2 , and their mixture on the explosion characteristics of CH 4 . The flammable limits tests were performed in an upward propagation cylindrical vessel with a volume of 3.4 L. The explosion properties of the mixtures were tested in a standard 20 L spherical chamber. All experiments were conducted at room temperature and at ambient pressure, with a relative humidity range from 52 to 73%. The parameters of flammable limits (upper flammable limit ( UFL ) and lower flammable limit ( LFL )), explosion risk value ( F ), peak explosion pressure ( P max ), maximum pressure rise rate (( d p /d t ) max ), and the gas deflagration index ( K G ) were observed and analyzed. The laminar burning velocity ( S L ) of the mixtures was determined by an outwardly propagating spherical flame method. The results indicated that the existence of C 2 H 6 , C 2 H 4 , CO, H 2 , and their mixture lowered the flammable limits of CH 4 -air, enlarged its flammable range, and increased its explosion risk value. Furthermore, with regard to the fuel-lean CH 4 -air mixture, the addition of the mixed gas with volume fraction of 2% would enhanced its P max , ( d p /d t ) max ) K G , and S L by 39.3%, 253%, 253%, and 13.6% respectively. However, the mixed gas negatively affected those of the fuel-rich mixture, reduced those parameters by 21.9%, 73%, 73%, and 29% respectively. With regard to the stoichiometric condition (9.5% CH 4 -air mixture), the mixed gas slightly lowered P max , ( d p /d t ) max , and K G ; however, it reduced S L more abruptly with a reduction of 29.6%.