Biogas production enhancement using nanocomposites and its combustion characteristics in a concentric flow slot burner

Abstract Biogas combustion is a very essential topic for the development of many industrial combustion systems and engines. This fuel can replace current fossil fuels used in burners, engines, and many other applications. Understanding the combustion characteristics of this fuel and its stability in highly turbulent flames of practical interest is the aim of this work. The percentage of CO2 in biogas varies between 25 % and 45 %, which affects the combustion stability and flame structure. The present work shows that the generation of biogas is improved by adding Ni-Co-Ferrite or Ni-ferrite nano-additives. In this work, we selected 25 flames of mixtures of natural gas and CO2, where the ratio of CO2 varies from 0% to 40 %. The flames are generated in a concentric flow slot burner that produces planar two-dimensional flames. The stability characteristics and the flame structure were investigated. The flame structure is presented in the form of temperature profiles in some selected flames using fine wire thermocouple measurements. The stability characteristics are illustrated for two limits of lifted flames and blow out. The production rate of biogas can be increased by almost 30% using nano-additives of Ni-Co-Ferrite or Ni-ferrite. The data show that the stability of the flames is affected significantly for the 40% CO2 mixture. Therefore, it is recommended to keep CO2 percentage up to 30% for stable turbulent biogas flames. On the other hand, partially premixed flames are highly stable for a certain level of mixture inhomogeneity at a mixing length ratio of L/D = 16. At this level, the mixture fraction fluctuations are expected to be within the flammability limits range based on previous investigations in round jet configuration.