A Model for the Freeze Start Behavior of a PEM Fuel Cell Stack

Author(s):  
Michael Mangold ◽  
Silvia Piewek ◽  
Olaf Klein ◽  
Achim Kienle

A simple model for the start-up of a proton exchange membrane fuel cell stack is proposed. The model covers a wide temperature range from temperatures below the freezing point of water to usual operation temperatures of a low-temperature fuel cell. Model equations are derived from first principles. They account for the effects of ice and liquid water on the stack behavior. The model is validated by experimental data published by Schießwohl [2009, “Experimental Investigation of Parameters Influencing the Freeze Start Ability of a Fuel Cell System,” J. Power Sources, 193(1), pp. 107–115.], and a good qualitative agreement is found. The applicability of the model to problems of operation strategies and stack design is demonstrated by simulation studies.

2020 ◽  
Vol 9 (1) ◽  
pp. 149
Author(s):  
Khlid Ben Hamad ◽  
Mohamed Tariq Kahn

It is a reality that future development in the energy sector is founded on the utilization of renewable and sustainable energy sources. These energy sources can empower to meet the double targets of diminishing greenhouse gas emissions and ensuring reliable and cost-effective energy supply. Fuel cells are one of the advanced clean energy technologies and have demonstrated their ability to be a decent substitute to address the above-mentioned concerns. They are viewed as reliable and efficient technologies to operate either tied or non-tied to the grid and power applications ranging from domestic, commercial to industrial. Among different fuel cell technologies, proton exchange membrane is the most attractive. Its connection to the utility grid requires that the power conditioning system serving as the interface between the stack and the grid operates accordingly. This study aims to model and control a power conditioning system for the grid-connection of a megawatt fuel cell stack. Besides the grid, the system consists of a 1.54 MW/1400 V DC proton exchange membrane fuel cell stack, a 1.3 MW/600 V three-level diode clamped inverter and an LCL filter which is designed to reduced harmonics and meet the standards such as IEEE 519 and IEC 61000-3-6. The power conditioning control scheme comprises voltage and current regulators to provide a good power factor and satisfy synchronization requirements with the grid. The frequency and phase are synchronized with those of the grid through a phase-locked-loop. The modelling and simulation are performed using Matlab/Simulink. The results show good performance of the proposed microgrid as well as the inverter design and control approach with a low total harmonic distortion of about 0.35% for the voltage and 0.19% for the current.   


Author(s):  
Søren Juhl Andreasen ◽  
Søren Knudsen Kær

The present work involves the development of a model for predicting the dynamic temperature of a high temperature proton exchange membrane (HTPEM) fuel cell stack. The model is developed to test different thermal control strategies before implementing them in the actual system. The test system consists of a prototype cathode air cooled 30 cell HTPEM fuel cell stack developed at the Institute of Energy Technology at Aalborg University. This fuel cell stack uses PEMEAS Celtec P-1000 membranes and runs on pure hydrogen in a dead-end anode configuration with a purge valve. The cooling of the stack is managed by running the stack at a high stoichiometric air flow. This is possible because of the polybenzimidazole (PBI) fuel cell membranes used and the very low pressure drop in the stack. The model consists of a discrete thermal model dividing the stack into three parts: inlet, middle, and end. The temperature is predicted in these three parts, where they also are measured. The heat balance of the system involves a fuel cell model to describe the heat added by the fuel cells when a current is drawn. Furthermore the model also predicts the temperatures when heating the stack with external heating elements for start-up, heat conduction through stack insulation, cathode air convection, and heating of the inlet gases in the manifold. Various measurements are presented to validate the model predictions of the stack temperatures.


Energy ◽  
2020 ◽  
pp. 119362
Author(s):  
Seok-Ho Seo ◽  
Si-Doek Oh ◽  
Jinwon Park ◽  
Hwanyeong Oh ◽  
Yoon-Young Choi ◽  
...  

Author(s):  
Frano Barbir ◽  
Haluk Gorgun ◽  
Xinting Wang

Pressure drop on the cathode side of a PEM (Proton Exchange Membrane) fuel cell stack has been studied and used as a diagnostic tool. Since the Reynolds number at the beginning of the flow field channel was <250, the flow through the channel is laminar, and the relationship between the pressure drop and the flow rate is linear. Some departure from linearity was observed when water was either introduced in the stack or produced inside the stack in the electrochemical reaction. By monitoring the pressure drop in conjunction with the cell resistance in an operational fuel cell stack, it was possible to diagnose either flooding or drying conditions inside the stack.


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