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TECHNICAL PAPERS

# Systematic Experimental Analysis of a Direct Methanol Fuel Cell

[+] Author and Article Information
A. Casalegno, R. Marchesi, F. Rinaldi

Dipartimento di Energetica, Politecnico di Milano, Milan, 20133, Italy

In this work, declared uncertainties have to be considered with a coverage factor of 2, which, assuming a normal distribution, is equivalent to 95% of population. If degrees of freedom (dof) are expressed, uncertainty includes a type-A contribution, otherwise just type-B contributions (11-12).

ANOVA are performed considering a probability test of 0.95.

A prudential increment of coverage factor is used, due to density data uncertainty.

The methanol concentration influence on current was evaluated in different cases, it has an order of $10−1A∕(%w)$.

The temperature influence on current was evaluated in different cases, it has an order of $10−1A∕K$.

Calibration was effectuated for different pump speeds with the two solutions used for this study, verifying, repeatability, and considering ambient temperature variation.

The anode flow rate influence on current was evaluated in different cases, it has an order of $1A∕(g∕min)$.

The voltage influence on current has been evaluated in different cases; it has an order of $10A∕V$.

J. Fuel Cell Sci. Technol 4(4), 418-424 (May 02, 2006) (7 pages) doi:10.1115/1.2756851 History: Received November 29, 2005; Revised May 02, 2006

## Abstract

Different studies are carried out to compare the performances of different fuel cell constructive materials and operating conditions. In this work, a methodology for the characterization of DMFC experimental results in term of uncertainty and repeatability and for a systematic analysis of operating condition influence on performance is presented. The measurement system (composed of calibrated instruments) and experimental and data elaboration procedures are described. Experimental results, characterized by uncertainty and repeatability, are discussed for different operating conditions: fuel cell temperature, anode flow rate, and methanol concentration. The influence of operating condition history on performance is observed. It arises also from accumulation, both of methanol and carbon dioxide at the anode side; consequently, the operating condition history has to be considered in evaluating direct methanol fuel cell (DMFC) performances and repeatability of measurements. This work confirms that to compare experimental performances of fuel cells, the measurements shall be characterized by traceability, repeatability, reproducibility, and uncertainty.

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## Figures

Figure 6

One-way polarization curves, with 400s transitory periods after each single point, operating conditions similar to experimental session 4

Figure 7

One-way polarization curves, with 400s transitory periods after each single point, operating conditions similar to experimental session 4

Figure 8

Repeatability analysis of experimental session 4, current values at 0.2V, 0.3V, and 0.4 V; mean value is shown

Figure 9

Repeatability analysis of experimental session 4, mean temperature value; mean value and uncertainty (9dof) are shown

Figure 10

Temperature influence, polarization curves, experimental sessions 1, 2, and 3

Figure 11

Temperature influence, polarization curves, experimental sessions 8, 9, and 12

Figure 12

Temperature influence, power density curves, experimental sessions 1, 2, and 3

Figure 13

Temperature influence, power density curves, experimental sessions 8, 9, and 12

Figure 14

Anode flow rate influence, polarization curves, experimental sessions 3, 4, and 5

Figure 15

Anode flow rate influence, polarization curves, experimental sessions 10, 11, and 12

Figure 16

Anode flow rate influence, polarization curves, experimental sessions 6, 7, and 8

Figure 17

Maximum and steady-state open circuit voltages

Figure 5

One-way polarization curves of experimental session 4

Figure 1

Experimental session 4: current in function of acquisition time, while voltage decreased and increased

Figure 2

Experimental session 3: current in function of acquisition time, while voltage decreased and increased

Figure 3

Experimental session 4: elaborated current data in function of acquisition time, while voltage is decreased and increased

Figure 4

One-way polarization curves of experimental session 4

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