Influence of Flow Channel Design on the Flow Pressure Drop and the Performance of Direct Methanol Fuel Cells

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Yong-Sheen Hwang ◽  
Suk-Won Cha ◽  
Hoon Choi ◽  
Dae-Young Lee ◽  
Seo Young Kim
Keyword(s):  
Fuel Cells ◽  
Pressure Drop ◽  
Direct Methanol Fuel Cells ◽  
Flow Channel ◽  
Channel Design ◽  
Balance Of Plant ◽  
Direct Methanol ◽  
Flow Pressure ◽  
Methanol Fuel Cells ◽  
Optimal Driving

We investigated the optimum flow channel design for direct methanol fuel cells (DMFCs). Especially, we explored the effect of the pressure drop across the inlet and outlet on the performance of the DMFCs with various flow channel designs. In DMFC systems, the optimization of such parameters are critical to minimize the power usage by the auxiliary devices, such as fuel pump and blowers. In this paper, we present how the pressure drop control may determine the optimal driving point of the DMFC stack. Also, we show how the optimal fuel utilization ratio may be achieved, without degrading the performance of DMFC stacks. Overall, we discuss how the flow channel design affects the selection of the balance of plant (BOP) components, the design of the DMFC system, and the efficiency of the entire system.

Effect of Anode Flow Channel Design on the Carbon Dioxide Bubble Removal in Direct Methanol Fuel Cells

2020 ◽  
Author(s):  
Sameer Osman ◽  
Shinichi Ookawara ◽  
Mahmoud Ahmed
Keyword(s):  
Carbon Dioxide ◽  
Fuel Cells ◽  
Diffusion Layer ◽  
Direct Methanol Fuel Cells ◽  
Gas Diffusion Layer ◽  
Gas Diffusion ◽  
Flow Channel ◽  
Methanol Oxidation Reaction ◽  
Direct Methanol ◽  
Methanol Fuel Cells

Abstract On the anode side of a direct methanol fuel cell, carbon dioxide bubbles are generated as a result of the methanol oxidation reaction. The accumulation of such bubbles prevents methanol from reaching the gas diffusion layer. Hence, a significant reduction in the reaction rate occurs, which limits the maximum current density of the cell. To keep carbon dioxide bubbles away from the gas diffusion layer interface, a new design of the anode flow channel besides wall surface treatment is developed. Such a design can introduce the Concus-Finn phenomena, which forces the carbon dioxide bubbles to move away from the gas diffusion layer due to capillary forces. This can be achieved by using a trapezoidal shape of the flow channel, as well as the combined effect of hydrophobic and hydrophilic surface treatments on the gas-diffusion layer and channel walls. To identify the optimal design of the anode flow channel, a three-dimensional, two-phase flow model is developed. The model is numerically simulated and results are validated with available measurements. Results indicated that treating the gas-diffusion layer with a hydrophilic layer increases the area in direct contact with liquid methanol. Besides, the hydrophobic top channel surfaces make it easier for the carbon dioxide bubbles to attach and spread out on the channel top surface. The current findings create a promising opportunity to improve the performance of direct methanol fuel cells.

The Entrance Effect of Pin Type Flow Channel on Direct Methanol Fuel Cells

2012 ◽  
Vol 28 (2) ◽  
pp. 361-364 ◽  
Author(s):  
T.-Y. Chen ◽  
Y.-T. Liao ◽  
Y.-D. Kuan
Keyword(s):  
Fuel Cells ◽  
Bubble Dynamics ◽  
Direct Methanol Fuel Cells ◽  
Flow Channel ◽  
Methanol Solution ◽  
Cell Performance ◽  
Flow Channels ◽  
Type Flow ◽  
Direct Methanol ◽  
Methanol Fuel Cells

AbstractThis research alters the traditional single inlet/outlet opening of the pin type flow channel of direct methanol fuel cells (DMFCs). Multi-inlet/outlet openings are designed with the aim to distribute the methanol solution evenly and effectively remove CO2 bubbles and to improve the cell performance. The CO2 bubble dynamics in anode flow channels and the cell performance are investigated. Results show that the newly designed flow channels can overcome restrictions resulting from fuel and effectively remove CO2 bubbles, thereby enhancing the performance of the pin type DMFC. The “three-inlet and three-outlet” design increases the current density output by 19%.

Carbon Dioxide Bubbles Removal by Capillary Actuation in the Anode Channel of Direct Methanol Fuel Cells

2020 ◽  
pp. 1-41
Author(s):  
Sameer Osman ◽  
Shinichi Ookawara ◽  
Mahmoud Ahmed
Keyword(s):  
Carbon Dioxide ◽  
Fuel Cells ◽  
Diffusion Layer ◽  
Direct Methanol Fuel Cells ◽  
Hydrophobic Surface ◽  
Flow Channel ◽  
Methanol Oxidation Reaction ◽  
Two Phase ◽  
Direct Methanol ◽  
Methanol Fuel Cells

Abstract On the anode side of a direct methanol fuel cell, carbon dioxide bubbles are generated as a result of the methanol oxidation reaction. The accumulation of such bubbles prevents methanol from reaching the diffusion layer (DL). Hence, a reduction in the reaction rate occurs, which limits the maximum current density of the cell. To keep carbon dioxide bubbles away from the diffusion layer surface, a new design of the anode flow channel besides wall surface treatment is developed. Such a design can introduce capillary actuation, which forces the carbon dioxide bubbles to move away from the diffusion layer due to capillary forces. This can be achieved by using a trapezoidal shape of the flow channel, as well as the combined effect of hydrophilic and hydrophobic surface treatments on the diffusion layer and top wall respectively. To identify the optimal design of the anode flow channel, a three-dimensional, two-phase flow model is developed. The model is numerically simulated and results are validated with available measurements. Results indicated that treating the diffusion layer with a hydrophilic layer increases the area in direct contact with liquid methanol. Besides, the hydrophobic top channel wall makes it easier for the carbon dioxide bubbles to attach and spread out on the top surface. However, superhydrophobic treatment of the top wall should be avoided, as it can cause difficulty in bubble extraction from the channel. The current findings create a promising opportunity to improve the performance of direct methanol fuel cells.

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