Effects of hydrogen enrichment on the heat generation and emission of natural gas turbulent premixed flame

Abstract

The demand for clean energy and the decarbonisation targets set globally require researching and developing new solutions. An efficient computational approach was implemented to examine the effect of hydrogen enrichment on flame characteristics, flame temperature, heat generation, NOx and carbon emissions under varying stoichiometry of combustion. Results showed that hydrogen enrichment significantly reduces CO2 emissions but also has undesirable effects which include reducing the heat generation capability of flame and increasing NOx emissions. The level of impact on each of these characteristics was found to be different. Under a boiler-like condition and stoichiometry (Ф = 0.8), a 10 % decrease in CO2 emissions was observed when enriching the fuel with 20 % hydrogen. Concurrently, the heat flux generated from the flame is reduced by 6 % and NOx emission is increased by 2 %. The effect of hydrogen enrichment on these aspects becomes more prominent at a higher enrichment level. The study also finds that making combustion leaner is an effective strategy to combat the effect of hydrogen enrichment with respect to CO2 and NOx emission generation. Despite the leaner combustion producing less emissions for any given hydrogen enrichment level, it significantly decreases the heat transfer capacity of the flame. Alongside these flame characteristics, the significant role of hydrogen enrichment on increasing water vapour (H2O) production was examined.