HUMIDITY COMPENSATION FOR FUEL CELL ZEROING IN RESPIRATORY GAS MEASUREMENT

摘要

The accuracy of respiratory gas measurements taken by electrochemical fuel cells is affected by changes in humidity. Such changes come more apparent after a monitoring bench containing fuel cells has been zeroed and then returned to the sampling mode where as measurement is taken of a respiratory gas sample. The difference in humidity between the sampling gas stream and the zeroing gas stream causes a zero drift in the fuel cell readings. A piece of Nafion3 tubing is used after the pneumatics manifold which switches between the two gas streams and the fuel cell bench in order to equilibrate the humidity in both the sample and zero gas streams.