Physical Simulator of Start-Up for Hybrid System Cathode Side

Abstract

A start-up test rig at TPG laboratory at the University of Genoa, Italy, has been designed and built for two main purposes: physically simulating different early start-up layout and procedures of high temperature fuel cell hybrid systems, and validating time-dependent hybrid system models based on TRANSEO software. Since start-up is a critical operating phase for high temperature fuel cell hybrid systems, and it may require specific modifications to the hybrid system layout, the start-up test rig is meant to be very flexible for testing several start-up layouts as well as the coupling of different turbomachines and stacks. Results for cold test, 700°C and 950°C start-up combustor outlet temperature tests are reported. Such results show the pressure and temperature quick rise during the early phase of start-up, which could represent an issue for the mechanical and thermal stress to the stack. A dynamic model of the test rig was built up and validated showing good agreement with the experimental results. This achievement was very useful to increase the confidence with predictive dynamic simulation tools during the start-up phase, where experimental data are hardly available and where the fuel cell materials may undergo risky thermal shocks.

Micro Gas Turbine Based Test Rig for Hybrid System Emulation

“…Further developments will regard the study of commercial microturbine improvement for fuel cell applications and the analysis of cathodic recirculations carried out by blowers or ejectors [22]. For this reason, the plant layout has been designed with the highest flexibility approach for the volume variation and an easy connection with new components, as cathodic blowers or ejectors.…”

“…Furthermore, at the compressor outlet a check valve (Fig.2) has been introduced to prevent damages and block compressor backflow if surge conditions occur during hybrid system emulation tests. Between this valve and the recuperator inlet a T-joint has been introduced to use a part of compressor outlet flow for a gradual heating up of the fuel cell volume, as requested by normal startup of real fuel cell stacks [22].…”

“…While different emulators, in reduced scale, are currently running at University of Genoa (TPG) to study the SOFC anode recirculation [21] and the cathode side early start-up phase [22] of hybrid systems, a new physical simulator for high temperature fuel cell hybrid systems has been developed by the TPG, inside FELICITAS European Integrated contract (TIP4-CT-2005-516270). This is a new test rig designed to study the coupling of a commercial machine (Turbec T100) with an apt volume for the fuel cell dimension and thermal capacitance, located between recuperator outlet and combustion chamber inlet.…”

“…As well described in this paper, the plant is equipped with a set of pipes designed for the measurement of the system properties (pressures, temperatures and mass flow rates) and for start-up and bleed reasons. A cold by-pass has been included to connect the volume directly to the compressor outlet with the objective to simulate a gradual heating up of the stack (mixing compressor outlet flow with the flow coming from recuperator), as required during the start-up phase [22].…”