Effect of the Regenerator Efficiency on the Performance of a Micro Gas Turbine Fed with Alternative Fuels

Abstract

In this paper a validated in-house MATLAB© model was used to assess the behaviour of the Turbec T100 MGT when operated with alternative low lower heating value (LHV) fuels; moreover, the effect of the cycle humidification is assessed. In both the aforementioned cases, the flow rates through the turbomachines, their operating points, and the effectiveness of the recuperator might change and determine performance losses. In particular, the recuperator in a MGT is a crucial component that allows to achieve good thermodynamic performance, also in presence of low compression ratios, and its performance can strongly influence the final output of the machine. Therefore, the aim of the work is to evaluate the effect of the variation of the operating conditions on the performance of the recuperator and, therefore, of the whole MGT. The use of alternative fuels with low LHV and of steam injection shifts the operative points of the turbomachines without strongly affecting their isentropic efficiency; in general, compression ratio is reduced and the flow rate of the compressor is reduced. Therefore, attention must be paid for the compressor stall limit. The recuperator shows a slight variation of the temperature of the fluids, but a higher efficiency is recorded as the flow rate are typically reduced and a better heat recovery performance can be obtained.