Micro gas turbines (mGT) are emerging power sources for distributed generation facilities considering their environment friendliness, high fuel flexibility and efficient cogeneration of heat and power (CHP). Numerical simulation and diagnostic tools are essential for cycle optimization of mGT and prediction of performance degradation.

This work is focused on fault diagnostics of T100 mGT through the application of AE-T100 model, a simulation tool, which has been developed within a collaboration between the University of Genoa (Unige) and Ansaldo Energia. This model has been developed for steady-state simulation of mGT in off-design conditions. Leveraging on previous efforts for model development, tuning, first phase of validation through Ansaldo Enegia test rig (AE-T100) and diagnostic application of the model, the present work deals with further utilization of the diagnostic capability of the model for mGT cycles. For this purpose, it was used in real operating conditions through the AE-T100 test rig for the diagnostic aim of some unexpected machine behavior. The model results indicated high deviation from the actual field data in terms of fuel flow and efficiency, and so justified the diagnostic capability of the AE-T100 tool.

Afterwards, based on the experimental observation of some bypass leakage from the burner in the same test rig, AE-T100 model was applied to model such leakage through the variation of AS ratio, leakage from the recuperator outlet to the ambient, combustor pressure drop and turbine section modification, and carried out the sensitivity analysis of these parameters. Sensitivity analysis has verified that the accurate impact of this leakage on overall mGT performance cannot be modeled with the help of AE-T100 tool in its current capacity. Therefore, some other investigations like analysis of compressor maps must be carried out to explain such a performance deviation in case of leakage. Afterwards, the analysis of compressor maps resulted from the operating conditions of the test conducted on the same machine after leakage repair, has highlighted the change in compressor operating point and thus, more efficient compressor functioning, which results in higher net power. Hence, this analysis has provided a more comprehensible explanation of this leakage impact on the mGT performance.

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