Development of Synthetic Jet Air Blower for Air-breathing PEM Fuel Cell
This paper presents a synthetic jet air blower actuated by PZT for air blowing for air-breathing micro PEM fuel cell. The several factors to affect the performance of air-breathing PEM fuel cell such as air flow rate, opening ratio and cathode open type in the cathode side were studied. Especially, an air flow rate is critical condition to improve its performance. In this paper, we developed a synthetic jet air blower to supply a high stoichiometric air flow. The synthetic jet mechanism is a zero mass flux device that converts electrical energy into the momentum. The synthetic jet actuation is usually generated by a traditional PZT actuator, which consists of a small cylindrical cavity, in/outlet channel and PZT diaphragms. The flow rate of the fabricated synthetic jet air blower was 400cc/min at 550Hz and its power consumption was very low under 0.3W. The proposed air-breathing PEM fuel cell which installed synthetic jet air blower was higher performance and stability during continuous operation than the air-breathing fuel cell without auxiliary device to supply the air. The results showed that the maximum power density was 188mW/cm at 400mA/cm. This maximum power density and durability were improved more than 40% and 20%, respectively. Keywords— Air-breathing PEM fuel cell, Synthetic jet air blower, Opening ratio, Power consumption.
Effects of cathode channel configurations on the performance of an air-breathing PEMFC
A mathematical model is developed for evaluating the effects of various channel dimensions on the performance of an air-breathing polymer electrolytes membrane fuel cell (PEMFC). The model, which is based on Nguyen's model, has been extended to include the natural convection to consider buoyancy effect in the channels, electro-chemical reaction in the catalyst layer, and concentration overpotential due to mass transportation limitation. Results from the model indicate that the concentration loss is more serious in natural convection than in forced convection, especially at small channel width, and the performance of air-breathing PEMFC could be improved by increasing the channel width to some extend. Results also show that the temperature, channel size, and air flow rate influence each other, and the performance cannot be improved infinitely by increasing the channel size, and thus the cathode flow field should be optimized. This model provides insights into many design issues of air-breathing fuel cell, and can be easily used as an optimal design tool for air-breathing PEMFC.
Design considerations for miniaturized PEM fuel cells
Abstract In this paper, we consider the design of a miniaturized proton-exchange membrane (PEM) fuel cell for powering 0.5–20 W portable telecommunication and computing devices. Our design is implemented on a silicon substrate to take advantage of advanced silicon processing technology in order to minimize production costs. The reduced length scales afforded by silicon processing allow us to consider designs that would be prohibited by excessive Ohmic losses in larger systems. We employ a mathematical model to quantify the effects of the secondary current distribution on two competing cell designs. In addition to the design of the cell itself, we discuss key integration issues and engineering trade-offs relevant to all miniaturized fuel cell systems: air movement, fuel delivery and water balance, thermal management and load handling.