Abstract
In this paper, the performance of a Roots pump for hydrogen recirculation in proton exchange membrane (PEM) fuel cell system is simulated based on CFD modeling. The Roots pump is in a three-lobe configuration with helical rotors, and it is developed specifically for fuel cell systems between 60 to 110 kW. A three-dimensional model of the Roots pump is established to predict the pump performance, including the flow rate and power consumption under various operating conditions. Extensive simulations were conducted and then verified experimentally by operating with working fluids of air and helium. Based on the validated CFD model, the contents of water vapor and nitrogen in the hydrogen recirculated are taken into account to evaluate the Roots pump performance numerically according to the actual conditions of the recirculating hydrogen at the stack outlet. It is shown that the volumetric efficiency and isentropic efficiency are improved with the increase fraction of water vapor and nitrogen. It is found that the performance of the Roots pump integrated in the PEM fuel cell system is between the performance of the pump working with air and helium. Finally, correlations of volumetric efficiency and isentropic efficiency are given based on the CFD results to show the general pattern of this kind of hydrogen pump. It is believed that these equations are very helpful to the design and operation control of the PEM fuel cell system.
Highlights
The proton exchange membrane (PEM) fuel cell system has been used increasingly more often in the applications of various vehicles due to its advantages, such as high efficiency, compact structure and because it is easy to start [1]
Sci. 2020, 10, 8069 components in the hydrogen supply loop and the behavior of the hydrogen pump has a significant impact on the performance the fuel cell system
The accurate prediction of the hydrogen pump performance is an essential task in the design and operation of the PEM fuel cell system
Summary
The proton exchange membrane (PEM) fuel cell system has been used increasingly more often in the applications of various vehicles due to its advantages, such as high efficiency, compact structure and because it is easy to start [1]. A sub-model for describing the performance of the hydrogen pump is a critical part in the system-level simulation in the design of a PEM fuel system [3,4]. It is very important for the realization of the control strategies during the operation of the fuel cell system [5,6]. The performance measured with dry and pure hydrogen on a test rig differs greatly from the performance of the pump integrated in the PEM fuel cell system. The theoretical modeling and simulation of the performance of the hydrogen pump becomes a feasible and effective solution to meet this need from the fuel cell system [11,12]
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