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In the present study, the effects of geometrical properties of gas flow channels on both current density and temperature distributions inside a polymer electrolyte membrane (PEM) fuel cell are investigated. The main purpose here is to clarify the effects of the variation of width, depth, and the ribs of flow channels on the fuel cell performance. To do this, the fuel cell is numerically simulated in two dimensions. The governing equations consist of the conservation of the electrical potential, Darcy’s law as alternative to the momentum equation, Maxwell-Stefan equation for mass transport, energy conservation, and electro-thermal equations along with the Butler–Volmer equation. Numerical results indicate that the width of channels and their ribs have more sensible effects than the depth of flow channels on the current density and temperature distributions and fuel cell performance. While the maximum temperature of the cell is increased by increasing the width of the flow channels, the current density distribution and fuel cell performance can be improved. By decreasing the width of their ribs or depth of channels, the performance of the fuel cell is improved and its maximum temperature is decreased.

Medical humidifier is one of the vital instruments for a respiratory patient in hospital, which is used to humidify the required oxygen for respiratory patients. The conventional type of humidifier, bubble humidifier, has some technical problems, including the need to drain condensed water and a lack of accurate control of air or oxygen required by the patient. In contrast, Membrane humidifier has exciting advantages, including the simplicity of the system, the absence of moving parts, very low noise, and the ability to control temperature and humidity. In this study, three configurations, including parallel, cross, and serpentine of a single module of a membrane humidifier according to the person's weight and breathing rate (the range of 10–28 SLPM) are numerically investigated. For validation of numerical models, a membrane humidifier experimental setup test is used. The obtained results indicated that the crossflow configuration for membrane humidifier has a minimum Dew Point Approach Temperature (DPAT) (2

In a polymer membrane fuel cell more than half of the chemical energy of hydrogen is converted to heat during generation of electricity. This causes an increase in the cell temperature. The Cooling field design has a significant role in cell cooling. The cell's performance and stability are reduced due to inappropriate heat dissipation. In this paper, the cooling flow and heat transfer in cooling plates with parallel channels in the polymer membrane fuel cell are simulated and a parametric study of the influence of cooling channels dimensions on the fuel cell thermal performance is performed based on three indexes: maximum surface temperature cooling (Tmax), the temperature uniformity on the surface (Ut), and pressure drop. Numerical results show that increasing the depth of the channels has an adverse effect on temperature characteristic; inaddition, the pressure drop decreases. Therefore, regarding constructional limitations and mechanical strength, use of channels with a depth of 1 mm is recommended. Increasing the width of the channels decreases the maximum surface temperature of the cooling plate, the temperature uniformity index, and the pressure drop. However, increasing the channel width more than 3 mm does not have a significant effect on the cooling performance. Increasing the distance between two channels adversely effects the thermal parameters as well as increases the pressure drop. Therefore, the distance between two cooling channels should not be more than 2 mm.

The fuel cell is an electrochemical energy converter that directly converts the chemical energy of the fuel into electrical current and heat. The fuel cell has been able to identify itself as a source of clean energy over the past few decades. In order to achieve the durability and stability of fuel cells, many parameters should be considered and evaluated Therefore, in this study, a single-channel high-temperature polymer exchange membrane fuel cell (HT-PEMFC) has been numerically simulated in three-dimensional, isothermal and single-phase approach. The distribution of the hydrogen and oxygen concentrations, as well as water in the anode and cathode, are shown; then the effect of different parameters of the operating pressure, the gas diffusion layer porosity, the electrical conductivity of the gas diffusion layer, the ionic conductivity of the membrane and the membrane thickness are investigated and evaluated on the fuel cell performance. The results showed that the pressure drop in the cathode channel was higher than the anode channel, so that the pressure drop in the cathode channel was higher than 9 bars but, in the anode channel was equal to 2 bars. By examining the species concentration, it was observed that their concentration at the entrance was higher and at the output was reduced due to participation in the reaction and consumption. Also, with increasing the operating pressure, the electrical conductivity of the gas diffusion layer and ionic conduction of the membrane, the performance of the fuel cell is improved.