Sponsor: US Army/ Connecticut Global Fuel Cell Center

Graduate Students: Saptarshi Basu

Project Summary

A fiber optic coupled diode laser sensor has been developed for in situ measurements of water vapor partial pressure and gas temperature in proton-exchange membrane (PEM) fuel cell systems. The bipolar plate of a prototypical PEM fuel cell was modified to allow for transmission of a near infrared laser beam through the flow channels on either the fuel or oxidizer side of its membrane-electrode assembly. The laser wavelength was scanned over several water ro-vibrational transitions and the light absorption was detected by measuring the transmitted laser power through one of the flow channels in the bi-polar plate. The intensity and line shape of the measured transition was used to extract path-averaged values for the water vapor partial pressure. Measurements were initially taken in a non-operating cell with known temperature and humidity input gas streams to calibrate and test the optical device. A technique for rapid determination of the water partial pressure and gas temperature was developed.

Measured water partial pressure in operating fuel cell versus cell current at inlet water partial pressure Ps=0.07 atm for a cell temperature of 60 °C

Partial pressure and temperature measurements for inlet Ps = 0.19 atm, cell temperature = 80 ◦C (Psat = 0.47 atm) with dynamic cycling.

Measured absorption coefficient and components of the curve fitting algorithm using four Voigt profile and a quadratic background

Experimental setup for calibration tests. Numerous thermocouples (T) were used to control the humidity of the cell.

Patents

S. Basu, M.W Renfro, B.M Cetegen, Fiber Optic based in-situ diagnostics for PEM fuel cells.

Publications

Basu, S., Xu, H., Renfro, M. W., and Cetegen, B. M. , “In-situ optical diagnostics for measurements of water vapor concentration and temperature in PEM fuel cell”, ASME Journal of Fuel Cell Science and Technology, Vol. 3, pp 1- 7, 2006

Basu, S., H. Gorgun, Renfro, M. W., and Cetegen, B. M., “In-situ Simultaneous Measurements of Temperature and Water Partial Pressure in a PEM Fuel Cell Under Steady State and Dynamic Cycling”,  Journal of Power Sources, Vol. 159, pp 987-994, 2006

Basu, S., Renfro, M. W., and Cetegen, B. M.,”Spatially-resolved optical measurements of water partial pressure and temperature in a PEM fuel cell under dynamic operating conditions”, Journal of Power Sources, Vol. 162, pp 286-293, 2006