The TPG is developing its technology demonstrator of the top economic hybrid system layout. This SOFC ready turbocharger-based hybrid system aims to provide technology evidence of the feasibility and controllability of the concept.
Such a solution establishes a real system including all components except for the SOFC stack, which is then emulated, therefore the real behaviour of the plant can be replicated avoiding the risk of failures into the stack.
The main components included in the top-economy hybrid system emulator are:
- a turbocharger provided by Honeywell Transportation Systems;
- a high temperature heat exchanger provided by HiFlux;
- a double skin pressure vessel with fuel cell emulator designed by UNIGE;
- two combustors, one designed by DLR and one by UNIGE;
- Connection pipes, mass-flow controllers, mass-flow meters, pressure probes, temperature sensors.
The top-economic layout is based on the general hybrid system layout, and features the following characteristics:
the core-engine of the MGT is substituted with a turbocharger consisting of compressor and turbine with no electrical generator – with a significant electro-mechanical simplification. The compressed air delivered by the impeller of the compressor enters the external skin of the pressure vessel with a temperature of approximately 200°C. Crossing this side of the plenum the air is heated up by the inner hot core where the SOFC emulator is placed. Furthermore, the warmed air is heated up to 550°C by the heat exchanger and sent back to the central entrance of the pressure vessel. A first burner brings the air at 860°C, the nominal working temperature for the SOFC, air that is then delivered to the turbine and after the expansion passes through the hot side of the heat exchanger.
For the turbocharger control, since the electrical generator is not present, a cold bypass valve (from compressor outlet to turbine inlet), and a wastegate valve (turbine bypass) will be employed. Finally, a bleed valve is introduced in the scheme to avoid surge problems and control turbocharger speed under emergency operations.