Liu demonstrated that the accumulation of liquid water columns in the cathode flow channels reduces the effective electrochemical reaction area, limiting mass transfer and worsening cell performance [3]. Wang noted that liquid water management significantly affects PEMFC performance, especially at high current density [4]. Therefore, suitable water and thermal management should be used to ensure that the proton exchange membrane is sufficiently hydrated to maintain high proton conductivity.Li reviewed more than 100 references related to water management in proton exchange membrane fuel cells (PEMFCs), with a particular focus on water flooding, its diagnosis and mitigation [5].
Trabold applied neutron imaging to research the distribution of water flooding, detecting in situ variation in the amount of water that is produced in an operating fuel cell [6].
Tests that were performed by Zhang revealed that performance gradually worsened as relative humidity declined from 100% to 25% [7].Most investigations of voltage and humidity in PEMFCs involve the insertion of small sensors into the cells. For example, David examined the temperature distribution in fuel cells using Fiber Bragg grating technology. The result revealed a difference between the temperatures of the inlet and the outlet of 1 ��C [8]. Inman measured in-situ the reaction temperature in an operating fuel cell by placing five fiber temperature sensors in it [9].
Hinds employed commercial temperature and humidity sensors, with a large active area, in a single cell PEMFC [2].
Nishikawa cut the flow channel plate to install a commercial humidity sensor. This method yielded information about the interior, but the cost and assembly were problematic [10].Wang utilized AV-951 an infrared temperature device to measure external temperature distribution under various operating conditions [11]. Karimi observed the distribution of water within fuel cell Dacomitinib stacks. His simulation results revealed that increasing the humidity promoted water flooding downstream [12]. Shimpalee simulated variations in temperature, humidity, and current in a PEMFC. His results demonstrated that water flooding downstream affected the fuel cell reaction, indirectly reducing the temperature and current [13].
In the aforementioned references, bipolar plates were cut and processed, and then sensors were inserted into fuel cells to measure internal physical values. This process can not only cause fuel leakage but also increase contact resistance. Along with invasive measurement, simulation can also identify water flooding. However, neither of these methods can be used to obtain accurate information on the interiors of fuel cells.