# Developing a Novel Design for a Tubular Solid Oxide Fuel Cell Current Collector
## 5 Results and Discussion
### Species Distribution  
Figure 8 below shows the hydrogen species distribution contour through the anode flow channel for the traditional and the developed design. Generally, the hydrogen concentration decreases gradually from the inlet to the outlet due to hydrogen consumption in chemical reactions. For the traditional design, it can be seen that the hydrogen consumption was very low compared to the newly developed trapezoidal design with different channels. This low hydrogen consumption was due to the small contact area of the collector with the anode and cathode, which explains the achieved low performance using traditional designs. The developed trapezoidal design with different channels showed good hydrogen consumption, leading to good performance compared to the traditional design.  
Figure 9 shows the mass flow rate of hydrogen at the outlet for each design. The maximum mass flow rate of hydrogen was detected for the traditional design, and therefore this design cannot make the best use of fuel (hydrogen). As concluded in Figure 7, increasing the number of channels in the developed trapezoidal design increased the collected current from the cell. This performance enhancement, achieved by increasing the number of channels in the developed trapezoidal design, is mainly due to an increase in the current collector's contact area with the cell, leading to the efficient collection of the current from the cell. Additionally, increasing the collected current should be accompanied by more  
Figure 8: Hydrogen concentration contour through the cell for different designs.  
hydrogen consumption. However, as shown in Figure 9, the lowest fuel mass flow rate was achieved when using the developed trapezoidal design with four channels and not when using the design with the highest number of channels. This was mainly because increasing the contact area (as is the case in the eight- and twelve-channel designs) decreases the interaction area of the fuel/air with the electrodes, and this hinders the fuel/air from reaching certain reaction sites and creates a high mass flow rate at the exit (Figure 9).  
Figure 10 shows the water vapor concentration contour through the cell for the traditional and the developed trapezoidal design with different channels. A high water vapor concentration at the exit means a greater extent of the reaction and a higher achieved performance. As shown in Figure 10, the lowest water vapor concentration was achieved when using the traditional design, meaning that only a weak reaction occurred with this design. This low vapor concentration also explains the traditional design's low performance. The developed trapezoidal designs with different channels achieved higher water vapor concentrations at the exit than the traditional design. This explains the good performance of these new designs.  
Figure 11 shows the mass flow rate of water vapor at the exit using all investigated designs. The traditional design gave the lowest mass flow rate at the exit compared to the developed trapezoidal designs with different channels. The trapezoidal design with four channels achieved the maximum mass flow rate of water vapor at the exit compared to the trapezoidal designs with eight and twelve channels. However, on the other hand, the collected current from this design was less than the collected current from the designs with eight and twelve channels. This finding was mainly due to the larger contact surface for the collector designs with twelve and eight channels compared with four. Therefore, they can collect more current from the cell than the design with four channels.