Numerical investigation of the upscaling of a new type of H2-O2 burner with water-cooled combustion

To prevent the heating of the earth a shift to CO2-neutral fuels is needed. One potential CO2-neutral fuel is hydrogen, which, however, leads to increased nitrogen oxide emissions when air is used due to higher adiabatic combustion temperatures. A completely emission-free use of hydrogen can be achieved by combustion with oxygen instead of air, but the adiabatic combustion temperatures then exceed 3300 K making this technologically difficult to realize. In this work, a recently proposed combustion process is investigated in which the combustion is cooled by liquid water. For this purpose, a burner with an integrated dual-fluid nozzle has been developed in a lab-scale version. The focus of the following work is the pressure based upscaling of the combustor. To investigate the influence of the increased pressure level numerical simulations up to 50 bar were performed. The results show the main reaction shifting away from the burner, caused by lower flame speeds due to higher pressure. Additional a decreased spray breakup is predicted, leading to inhomogenous temperature distributions compared to atmospheric pressure conditions. The results are used to develop a geometric scaled burner for the operation in high pressure conditions.