Reliability of Vapor Transport Measurement in a Hollow Fiber Membrane Humidifier

The uncertainty analysis of moisture measurements in the hollow fiber membrane was conducted in this study to ensure the reliability of a design for membrane humidifiers.As moisture is pivotal for proton exchange membrane fuel cell durability and performance, it is necessary to humidify the reactant gases.In vehicular fuel cells, membrane humidifiers have been implemented to regulate the water content levels of cathode air, thereby avoiding fuel cell operation limitations, particularly in high-temperature environments.Minimized error in measurements of water exchange is required to improve the effectiveness of shelltube membrane humidifier design.The uncertainty analysis was conducted through parametric experiments under isothermal conditions with varying conditional parameters, including temperature, pressure, and inlet relative humidity.The transport metric is represented by the vapor transfer rate from wet to dry air through the membrane, which is affected by the sensitivity of the corresponding operating parameters and sensor reliability.Therefore, the error of each conditional (input) parameter and the overall error of the measured result (water transfer rate) were determined to evaluate the quality of measurements.From the analysis, the most sensitive factor was discovered to be the inlet relative humidity, with error increasing as temperature increased.The uncertainty of water transport measurements was highest at 90℃, amounting to 3.97%.Consequently, it can be concluded that the measurement of water transport in the membrane humidifier meets good reliability for further design and investigation.