PEM （Proton Exchange Membrane） fuel cell is a promising renewable energy source to a wide range of applications for its clean products and high power density. However, controlling its humidity is a challenging probl...PEM （Proton Exchange Membrane） fuel cell is a promising renewable energy source to a wide range of applications for its clean products and high power density. However, controlling its humidity is a challenging problem due to the interdependence of several phenomena contributing in membrane＇s water content. This work deals with efficiency improvement of PEM fuel cells via humidity control. An innovative strategy of control based on the model of Ref. [1] is proposed. It consists on regulating gas humidification rates according to the power demand so that to minimize power losses. The proposed control takes into consideration constraints related to humidification in order to avoid dry out or flooding of the membrane. Simulations results show that time-phasing between hydrogen and oxygen humidification rates plays an important role in minimizing power losses. The proposed control shows significant improvement in the fuel cell＇s efficiency up to 20%.展开更多
Water management is of great importance to maintain performance and durability of proton exchange membrane fuel cells. This paper presents a novel proton exchange membrane (PEM) fuel cell with a humidification zone in...Water management is of great importance to maintain performance and durability of proton exchange membrane fuel cells. This paper presents a novel proton exchange membrane (PEM) fuel cell with a humidification zone in the membrane electrode assembly (MEA) of each cell, in which the moisture of the cathode exhaust gas could transfer through the membrane to humidify anode or cathode dry gas. With a simple model, the relative humidity (RH) of the dry air exhaust from a membrane humidifier with 100% RH stream as a counter flow is calculated to be 60.0%, which is very close to the experimental result (62.2%). Fuel cell performances with hydrogen humidifying, air humidifying and no humidifying are compared at 50, 60 and 70°C and the results indicate that humidifying is necessary and the novel design with humidifying zone in MEA is effective to humidify dry reactants. The hydrogen humidifying shows better performance in short term, while water recovered is limited and the stability is not as good as air humidifying. It is recommended that both air and hydrogen should be humidified with proper design of the humidifying zones in MEA and plates.展开更多
文摘PEM （Proton Exchange Membrane） fuel cell is a promising renewable energy source to a wide range of applications for its clean products and high power density. However, controlling its humidity is a challenging problem due to the interdependence of several phenomena contributing in membrane＇s water content. This work deals with efficiency improvement of PEM fuel cells via humidity control. An innovative strategy of control based on the model of Ref. [1] is proposed. It consists on regulating gas humidification rates according to the power demand so that to minimize power losses. The proposed control takes into consideration constraints related to humidification in order to avoid dry out or flooding of the membrane. Simulations results show that time-phasing between hydrogen and oxygen humidification rates plays an important role in minimizing power losses. The proposed control shows significant improvement in the fuel cell＇s efficiency up to 20%.
基金Supported by the National High Technology Research and Development Program of China (2008AA05Z104)
文摘Water management is of great importance to maintain performance and durability of proton exchange membrane fuel cells. This paper presents a novel proton exchange membrane (PEM) fuel cell with a humidification zone in the membrane electrode assembly (MEA) of each cell, in which the moisture of the cathode exhaust gas could transfer through the membrane to humidify anode or cathode dry gas. With a simple model, the relative humidity (RH) of the dry air exhaust from a membrane humidifier with 100% RH stream as a counter flow is calculated to be 60.0%, which is very close to the experimental result (62.2%). Fuel cell performances with hydrogen humidifying, air humidifying and no humidifying are compared at 50, 60 and 70°C and the results indicate that humidifying is necessary and the novel design with humidifying zone in MEA is effective to humidify dry reactants. The hydrogen humidifying shows better performance in short term, while water recovered is limited and the stability is not as good as air humidifying. It is recommended that both air and hydrogen should be humidified with proper design of the humidifying zones in MEA and plates.
