Abstract
A mobile fuel cell systems power output can be increased by pressure amplification using an electric turbocharger. These devices are subject to frequent transient manoeuvres due to a multitude of load changes during the mission in automotive applications. In this paper, the authors describe a simulation approach for an electric turbocharger, considering the impact of moist air and condensation within the cathode gas supply system. Therefore, two simulation approaches are used: an iterative simulation method and one based on a set of ordinary differential equations. Additional information is included from turbine performance maps taking into account condensation using Euler–Lagrange CFD simulations, which are presented. The iterative calculation approach is well suited to show the impact of condensation and moist air on the steady state thermodynamic cycle and yields a significant shift of the steady state operating line towards the surge line. It is shown that a substantial risk of surge occurs during transient deceleration manoeuvres triggered by a load step.
Highlights
With the increasing demand for CO2 neutral automotive transportation, electric drive concepts are moving into the focus of development
This study aims to highlight the steady state and transient performance of an electric turbocharger for mobile fuel cell applications
Steady state operating lines have been calculated over the operating range from a net system power output of 19.5% to 82.8% of the stack design power output Pf c,Des
Summary
With the increasing demand for CO2 neutral automotive transportation, electric drive concepts are moving into the focus of development. Fuel cells are a promising power source for the mobility sector, especially for land and air transportation. With the help of hydrogen from green sources, proton exchange membrane fuel cells (PEMFCs) can be operated in mobile machines without direct emission of CO2. This is the most common type used in this field of application [1,2]. The main task of the cathode gas supply is to provide preconditioned cathode gas that has a temperature, humidity and pressure set according to the operation of the stack [6]. The pressure potential is extracted from the exhaust gas in a radial turbine downstream of the fuel cell stack. It was found that a significant impact on the turbine efficiency and mass flow rate occurs, which needs to be taken into account when analysing the overall system performance
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