Impact of Condensation on the System Performance of a Fuel Cell Turbocharger

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.

On the Impact of Condensation and Liquid Water on the Radial Turbine of a Fuel Cell Turbocharger

“…Instead, a performance map is only valid for one specific humidity. More detailed discussions of this phenomenon were published earlier [10,13].…”

“…In this approach, a polytropic expansion calculation without condensation is carried out first, followed by a calculation of the thermodynamic equilibrium with isentropic condensation. This method is discussed in more detail by [3,13]. The calculation assumes that the liquid water is completely separated after each turbine stage, that the turbine stages have a polytropic efficiency of 90% and that the flow velocity at the inlet and outlet of the turbines is 50 m s −1 in each case.…”

“…This includes a summary of the effects that a turbine affected by condensation can have on the entire air-management system, see Section 3.6. This summary was provided by Lück et al [13], who used the results of Wittmann et al [10] as input data for their transient system analysis of an entire PEMFC air-management system with condensation in the turbine. Electrically turbocharged air-management system for a proton exchange membrane fuel cell (PEMFC).…”

Numerical Analysis of the Effects of Grooved Stator Vanes in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow

“…Some works present different APUs configuration as an alternative to conventional systems where some arrangements are based on a hybrid propulsion configuration, i.e., with a more strongly electric concept, reducing the source of pollution [3,4]. Radial turbines can be used in environmental control system (ECS) or in high-altitude fuel cell [1,5] aircraft operation due to the high pressure ratios involved [6,7].…”

Experimental analysis and multidimensional modeling of water condensation due to low-pressure exhaust gas recirculation activation during engine cold starts

“…In particular, hydrogen engines need a massive amount of EGR in the combustion process with a huge amount of H 2 O as gas, producing in the EGR coolers (HP and LP) unwanted water condensation [192]. Focusing on fuel cell vehicles, a humidification is performed before the fuel cell membrane and a turbine is placed after the membrane to supply power in the compressor, this process of gas expansion with highly humid air inside the turbine produces condensation that could be studied with the contributions and models of this thesis [193,39].…”