Assessment of existing H2/O2 chemical reaction mechanisms at reheat gas turbine conditions

TL;DR

This study compares various hydrogen reaction mechanisms at high temperatures and pressures relevant to gas turbines, highlighting significant differences in their predictions and the scarcity of conclusive data for mechanism validation.

Contribution

It provides a detailed comparison of existing hydrogen reaction mechanisms under turbine conditions, identifying discrepancies and the need for further data validation.

Findings

Significant differences in elementary reaction coefficients among mechanisms.

Deviations in ignition delay and flame speed predictions between mechanisms.

Limited experimental data at high temperature and pressure conditions.

Abstract

This paper provides detailed comparisons of chemical reaction mechanisms of H2 applicable at high preheat temperatures and pressures relevant to gas turbine and particularly Alstom's reheat gas turbine conditions. It is shown that the available reaction mechanisms exhibit large differences in several important elementary reaction coefficients. The reaction mechanisms are assessed by comparing ignition delay and laminar flame speed results obtained from CHEMKIN with available data, however, the amount of data at these conditions is scarce and a recommended candidate among the mechanisms can presently not be selected. Generally, the results with the GRI-Mech and Leeds mechanisms deviate from the Davis, Li, O'Conaire, Konnov and San Diego mechanisms, but there are also significant deviations between the latter five mechanisms that altogether are better adapted to hydrogen. The differences in ignition delay times between the dedicated hydrogen mechanisms (O'Conaire, Li and Konnov) range from approximately a maximum factor of 2 for the H2-air cases, to more than a factor 5 for the H2/O2/AR cases. The application of the computed ignition delay time to reheat burner development is briefly discussed.