Humidification strategy for polymer electrolyte membrane fuel cells – A review (original) (raw)

Humidification studies on polymer electrolyte membrane fuel cell

Journal of Power Sources, 2001

Two methods of humidifying the anode gas, namely, external and membrane humidi®cation, for a polymer electrolyte membrane fuel (PEMFC) cell are explained. It is found that the water of solvation of protons decreases with increase in the current density and the electrode area. This is due to insuf®cient external humidi®cation. In a membrane-based humidi®cation, an optimum set of parameters, such as gas¯ow rate, area and type of the membrane, must be chosen to achieve effective humidi®cation. The present study examines the dependence of water pick-up by hydrogen on the temperature, area and thickness of the membrane in membrane humidi®cation. Since the performance of the fuel cell is dependent more on hydrogen humidi®cation than on oxygen humidi®cation, the scope of the work is restricted to the humidi®cation of hydrogen using Na®on 1 membrane. An examination is made on the dependence of water pick-up by hydrogen in membrane humidi®cation on the temperature, area and thickness of the membrane. The dependence of fuel cell performance on membrane humidi®cation and external humidi®cation in the anode gas is also considered. #

Study of a porous membrane humidification method in polymer electrolyte fuel cells

International Journal of Hydrogen Energy, 2011

A gas humidification subsystem that does not add to the parasitic power loss is advantageous for water management in PEMFC. A membrane humidifier was fabricated with porous membrane and the performance of the single cell using this humidifier has been evaluated. The study shows that the performance of the humidifier is comparable to that of the bubble humidifier. It was further found that the humidifier is suitable for both water and exhaust cathode air as the humidifying medium.

Relative humidity control in polymer electrolyte membrane fuel cells without extra humidification

Journal of Power Sources, 2008

The performance of polymer electrolyte membrane fuel cells is highly influenced by the water content in the membrane. To prevent the membrane from drying, several researchers have proposed extra humidification on the input reactants. But in some applications, the extra size and weight of the humidifier should be avoided. In this research a control technique, which maintains the relative humidity on saturated conditions, is implemented by adjusting the air stoichiometry; the effects of drying of membrane and flooding of electrodes are considered, as well. For initial analysis, a mathematical model reveals the relationship among variables that can be difficult to monitor in a real machine. Also prediction can be tested optimizing time and resources. For instance, the effects of temperature and humidity can be analyzed separately. For experimental validation, tests in a fault tolerant fuel cell are conducted.

Nafion® Tubing Humidification System for Polymer Electrolyte Membrane Fuel Cells

Energies

Humidity and temperature have an essential influence on PEM fuel cell system performance. The water content within the polymeric membrane is important for enhancing proton conduction and achieving high efficiency of the system. The combination of non-stationary operation requests and the variability of environment conditions poses an important challenge to maintaining optimal membrane hydration. This paper presents a humidification and thermal control system, to prevent the membrane from drying. The main characteristics of such a device are small size and weight, compactness and robustness, easy implementation on commercial fuel cell, and low power consumption. In particular, the NTHS method was studied in a theoretical approach, tested and optimized in a laboratory and finally applied to a PEMFC of 1 kW that supplied energy for the prototype vehicle IDRA at the Shell Eco-Marathon competition. Using a specific electronic board, which controls several variables and decides the optima...

Effects of flow field and diffusion layer properties on water accumulation in a PEM fuel cell

International Journal of Hydrogen Energy, 2007

Water is the main product of the electrochemical reaction in a proton exchange membrane (PEM) fuel cell. Where the water is produced over the active area of the cell and how it accumulates within the flow fields and gas diffusion layers, strongly affects the performance of the device and influences operational considerations such as freeze and durability. In this work, the neutron radiography method was used to obtain two-dimensional distributions of liquid water in operating 50 cm 2 fuel cells. Variations were made of flow field channel and diffusion media properties to assess the effects on the overall volume and spatial distribution of accumulated water. Flow field channels with hydrophobic coating retain more water, but the distribution of a greater number of smaller slugs in the channel area improves fuel cell performance at high current density. Channels with triangular geometry retain less water than rectangular channels of the same cross-sectional area, and the water is mostly trapped in the two corners adjacent to the diffusion media. It was also found that cells constructed using diffusion media with lower in-plane gas permeability tended to retain less water. In some cases, large differences in fuel cell performance were observed with very small changes in accumulated water volume, suggesting that flooding within the electrode layer or at the electrode-diffusion media interface is the primary cause of the significant mass transport voltage loss.