Experimental Investigation on a Recuperator for Hybrid System Applications

The aim of this work is the experimental analysis of steady-state and transient behavior of a primary surface recuperator installed in a 100 kW commercial micro gas turbine. The machine is integrated in an innovative test rig for high temperature fuel cell hybrid system emulation, designed and installed by Thermochemical Power Group at the University of Genoa in the framework of the Felicitas and LARGE-SOFC European Integrated Projects. The high flexibility of the rig was exploited to perform tests on the recuperator operating in the standard cycle focusing the attention on its performance in transient condition. Start-up tests were carried out in both electrical grid-connected and stand-alone conditions operating with different control strategies. The attention is focused on system response due to control strategy and on boundary temperatures variation for its influence on component life consumption. Further tests were carried out using the valves installed on the test rig to bypass the air side of the unit. Different operative conditions were analyzed to show the effect of different flow rates on recuperator behavior. The attention is mainly focused on recuperator performance when it operates in unbalanced flow rate conditions (i.e. different mass flow rate values in recuperator sides).