In order to compare with other researches, we list variables that involved in the experiment:
P = f (A, Q, )
Where P is power density, A is active area, Q is flow rate and is clamping pressure. Then we apply the pi theorem to determine the pi terms which is:
π =
The higher number of π means that it requires less flow rate and clamping pressure to reach the same power density. Besides, the power output increases with an increasing of active area of PEMFC.
Figure 4.64 showed that the PDMS PEMFC has higher number of π than that of the graphite one and Hsu’s study of micro PDMS one [3] under the same clamping pressure. For instance, under the same clamping pressure of 65.5N/cm2, the number of π of PDMS PEMFC is 0.774 which is larger than that of graphite one and Hsu’s [3] which is 0.437 and 0.484, respectively.
Fig. 4.1 Reference Case
0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 -10
0 10 20 30 40 50 60 70 80 90 100
Resistance (Ohm.cm2 )
Current density (mA/cm2) AC resistance meter Value of voltage/current
Fig. 4.2 Value of AC Meter and Voltage/Current for Comparison
84
Fig. 4.3 I-P Curves in Different Flow Rates (PDMS PEMFC)
0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375
Fig. 4.4 I-V Curves in Different Flow Rates (PDMS PEMFC)
0 10 20 30 40 50 60 70 80 90 100 110 120 Measured data by mass flow meter Calculated data by current translation
Fig. 4.5 Comparison between Measured and Calculated Utilization (PDMS PEMFC) Measured data by mass flow meter Calculated data by current translation
Fig. 4.6 Comparison between Measured and Calculated Utilization after Eliminating Water Vapor (PDMS PEMFC)
86
Fig. 4.7 Pictures of Inlet and Outlet of Fuel Cell (PDMS PEMFC)
Fig. 4.8 Thermal Images in Hydrogen Flow Rate of 10sccm
Fig. 4.9 Temperature Distribution Analyses in Hydrogen Flow Rate of 10sccm (PDMS PEMFC)
88
Fig. 4.10 Thermal Images in Hydrogen Flow Rate of 20sccm
Fig. 4.11 Temperature Distribution Analyses in Hydrogen Flow Rate of 20sccm (PDMS PEMFC)
Fig. 4.12 Thermal Images in Hydrogen Flow Rate of 30sccm
Fig. 4.13 Temperature Distribution Analyses in Hydrogen Flow Rate of 30sccm (PDMS PEMFC)
90
Fig.
4.14 Thermal Images in Hydrogen Flow Rate of 40sccm
Fig. 4.15 Temperature Distribution Analyses in Hydrogen Flow Rate of 40sccm (PDMS PEMFC)
Fig. 4.16 Thermal Images in Hydrogen Flow Rate of 50sccm
Fig. 4.17 Temperature Distribution Analyses in Hydrogen Flow Rate of 50sccm (PDMS PEMFC)
92
Fig. 4.18 Thermal Images in Hydrogen Flow Rate of 60sccm
Fig. 4.19 Temperature Distribution Analyses in Hydrogen Flow Rate of 60sccm (PDMS PEMFC)
0 25 50 75 100 125 150 175 200 225 250 275 300 325 350
Fig. 4.20 I-P Curves in Different Clamping Forces (PDMS PEMFC)
0 25 50 75 100 125 150 175 200 225 250 275 300 325 350
Fig. 4.21 I-V Curves in Different Clamping Forces (PDMS PEMFC)
94
Fig. 4.22 I-R Curves in Different Clamping Forces (PDMS PEMFC)
Fig. 4.23 Durability Test for 24 Hours (PDMS PEMFC)
(a) (b)
(c) (d)
Fig. 4.24 Pictures of Water Accumulation at 0.5V (PDMS PEMFC) (a) 6 hours (b) 12 hours (c) 18 hours (d) 24 hours
96
(a) (b)
(c) (d)
Fig. 4.25 Pictures of Water Accumulation at 0.6V (PDMS PEMFC) (a) 6 hours (b) 12 hours (c) 18 hours (d) 24 hours
(a) (b)
(c) (d)
Fig. 4.26 Pictures of Water Accumulation at 0.7V (PDMS PEMFC) (a) 6 hours (b) 12 hours (c) 18 hours (d) 24 hours
98
Fig. 4.27 Thermal Images at 0.5V (PDMS PEMFC)
0 5 10 15 20 25 30 35 40 45 50 55 20
30 40 50 60 70 80 90 100
Temperature (o C)
Horizontal axis X (mm)
Line 1 Line 2 Line 3 Line 4 Line 5 Line 6 Line 7 Line 8 Line 9
Fig. 4.28 Thermal Images at 0.6V (PDMS PEMFC)
100
Fig. 4.29 Thermal Images at 0.7V (PDMS PEMFC)
0 20 40 60 80 100 120 140 160 180 200 220
Fig. 4.30 I-P Curves in Different Flow Rates (Graphite PEMFC)
0 20 40 60 80 100 120 140 160 180 200 220
Fig. 4.31 I-V Curves in Different Flow Rates (Graphite PEMFC)
102
Fig. 4.32 Thermal Images in Hydrogen Flow Rate of 10sccm (Graphite PEMFC)
Fig. 4.33 Temperature Distribution Analyses in Hydrogen Flow Rate of 10sccm (Graphite PEMFC)
Fig. 4.34 Thermal Images in Hydrogen Flow Rate of 20sccm (Graphite PEMFC)
Fig. 4.35 Temperature Distribution Analyses in Hydrogen Flow Rate of 20sccm (Graphite PEMFC)
104
Fig. 4.36 Thermal Images in Hydrogen Flow Rate of 30sccm (Graphite PEMFC)
Fig. 4.37 Temperature Distribution Analyses in Hydrogen Flow Rate of 30sccm (Graphite PEMFC)
Fig. 4.38 Thermal Images in Hydrogen Flow Rate of 40sccm (Graphite PEMFC)
Fig. 4.39 Temperature Distribution Analyses in Hydrogen Flow Rate of 40sccm (Graphite PEMFC)
106
Fig. 4.40 Thermal Images in Hydrogen Flow Rate of 50sccm (Graphite PEMFC)
Fig. 4.41 Temperature Distribution Analyses in Hydrogen Flow Rate of 50sccm (Graphite PEMFC)
Fig. 4.42 Thermal Images in Hydrogen Flow Rate of 60sccm (Graphite PEMFC)
Fig. 4.43 Temperature Distribution Analyses in Hydrogen Flow Rate of 60sccm (Graphite PEMFC)
108
Fig. 4.44 I-P Curves in Different Clamping Forces (Graphite PEMFC)
0 25 50 75 100 125 150 175 200 225
Fig. 4.45 I-V Curves in Different Clamping Forces (Graphite PEMFC)
0 25 50 75 100 125 150 175 200
0 25 50 75 100 125 150 175 200
Fig. 4.46 I-R Curves in Different Clamping Forces (Graphite PEMFC)
0 25 50 75 100 125 150 175 200 225 250 275 300 325
Fig. 4.47 I-P Curves in Different Cell Temperatures (Graphite PEMFC)
110
Fig. 4.48 I-V Curves in Different Cell Temperatures (Graphite PEMFC)
0 25 50 75 100 125 150 175 200 225 250 275 300 325 350
Fig. 4.49 I-R Curves in Different Cell Temperatures (Graphite PEMFC)
Fig. 4.50 Durability Test for 24 Hours (Graphite PEMFC)
112
(a) (b)
(c) (d)
Fig. 4.51 Pictures of Water Accumulation at 0.5V (Graphite PEMFC) (a) 6 hours (b) 12 hours (c) 18 hours (d) 24 hours
(a) (b)
(c) (d)
Fig. 4.52 Pictures of Water Accumulation at 0.6V (Graphite PEMFC) (a) 6 hours (b) 12 hours (c) 18 hours (d) 24 hours
114
(a) (b)
(c) (d)
Fig. 4.53 Pictures of Water Accumulation at 0.7V (Graphite PEMFC) (a) 6 hours (b) 12 hours (c) 18 hours (d) 24 hours
0 5 10 15 20 25 30 35 40 45 50 55
Fig. 4.54 Thermal Images at 0.5V (Graphite PEMFC)
116
Fig. 4.55 Thermal Images at 0.6V (Graphite PEMFC)
0 5 10 15 20 25 30 35 40 45 50 55
Fig. 4.56 Thermal Images at 0.7V (Graphite PEMFC)
118
Fig. 4.57 Durability Test for 24 Hours after Improvement (Graphite PEMFC)
(a) (b)
(c) (d)
Fig. 4.58 Pictures of Water Accumulation at 30 Kgf∙cm and Room Temperature (Graphite PEMFC) (a) 6 hours (b) 12 hours (c) 18 hours (d) 24
hours
120
(a) (b)
(c) (d)
Fig. 4.59 Pictures of Water Accumulation at 100 Kgf∙cm and Room Temperature (Graphite PEMFC) (a) 6 hours (b) 12 hours (c) 18 hours (d) 24
hours
(a) (b)
(c) (d)
Fig. 4.60 Pictures of Water Accumulation at 100 Kgf∙cm and 60℃ (Graphite PEMFC) (a) 6 hours (b) 12 hours (c) 18 hours (d) 24 hours
122
Fig. 4.61 Comparison between PDMS and Graphite PEMFC under the Same Conditions
Fig. 4.62 Comparison between PDMS and Graphite PEMFC under the Same Resistance
Fig. 4.63 Comparison between PDMS and Graphite PEMFC
Fig. 4.64 Comparison with Hsu’s study [3]
124 demonstrated. The experimental parameters included flow rate with the corresponding hydrogen utilization and clamping force. Secondly, the similar performance experiments on single graphite air-breathing PEMFC were also carried out and illustrated. The experimental parameters consisted of flow rate, clamping force and cell temperature. For both experimental studies, the corresponding thermal imagines of resultant temperature distributions on the cathode surface were given as well. In addition, in order to justify the durability of continuous usage and water produced situation, both fuel cells mentioned above were tested for 24 hours at a fixed operating voltage. Finally, we made a comparison between PDMS and graphite PEMFCs to see the 60sccm, and the corresponding thermal image show its temperature distribution being more uniform.