Investigation on combustion efficiency of the hydrogen–oxygen mixture at various pressures and excess oxidizer based on experimental and theoretical studies

Abstract

One of the ways to improve the efficiency of power plants, including nuclear power plants, can be the use of hydrogen energy complexes and hydrogen-oxygen steam generators in their composition. This is done by electrolysis production of hydrogen and oxygen and their further use in technological schemes of power units in the form of thermal energy. Fundamental in assessing the efficiency of such use of hydrogen technologies is the efficiency of hydrogen combustion in oxygen medium under different schematic-parametric conditions. In this paper combustion processes were studied in terms of evaluating efficiency of the hydrogen-oxygen mixture combustion at various pressures and an oxidizer excess. For this purpose, a calculation model of combustion processes of the hydrogen-oxygen mixture, including heat and mass transfer under the boundary conditions of the experiment was verified on the basis of the experimental data, obtained at 4-section flame tube. Has shown that increasing the pressure of the combustion products leads to a noticeable decrease in hydrogen underburning. The maximum effect is observed in the third section of the flame tube (a reduction by 56.72%), and the minimum effect is found in the first section (a reduction by 7.58%). In this case, the average specific reduction in hydrogen underburning in sections I-IV of the flame tube within the considered pressure ranged between 8.13, 17.41, and 31.34%/MPa, respectively. An increase in an oxidizer excess lead to a regular decrease in hydrogen underburning. In this case, the maximum decrease in hydrogen underburning is achieved with an oxidizer excess ratio of 2 in the third section of the flame tube (a reduction by 58.86%). At the same time, an increase in the positive effect of increasing pressure is observed. In this case, in the first two sections of the flame tube, the greatest dependence on the increase of an oxidizer excess ratio is observed. Thus, the maximum relative reduction in hydrogen underburning is achieved at the pressure of 6 MPa, and as a result amounts to 24.46% and 43.5% with the oxidizer excess ratio at 1.5 and 2, respectively.