Parameters estimation is important in fuel cell modelling and it remains a challenging task to predict. One of the most discussed parameters is the water diffusion coefficient in Nafion R membrane, which has a huge variation (10 −9 and 10 −5 cm 2 s −1 ), based upon the viewpoints of different authors. In this article, the estimation of the effective water diffusion coefficient through water balance method is presented and the effects of relative humidity gradient and cell temperature are explained. The membrane used in this work is Nafion R NRE 211 tested at a temperature of 60 • C and 70 • C with air flows. The value of water flux passing through the membrane is used to calculate the effective diffusion coefficient. A value in the range of 1 × 10 −7 to 4 × 10 −7 cm 2 s −1 is reported and it shows that the water balance method can be applied easily to measure an effective membrane water diffusion coefficient.

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It is of utmost importance to develop light weight fuel cell stacks and find the ways to integrate these to light weight and low temperature fuel cell systems. In order to meet the future energy demands non-polluting, compact, transportation and portable applications are required. Current energy systems have lower power density (kW/kg) resulting in optimized power only at higher overall weight. Systems with higher power density demands higher initial setup costs. Low temperature PEMFC, on other hand offers various advantages but fails to provide the required output without exceeding the weight of the fuel cell stack and thereby fuel cell systems. A fuel cell system consists of a fuel cell stack, compressed gas in cylinder, pressure relief valves, regulators, water pump, sensors and cvm. A fuel cell stack is the main component consisting of one of the devices with maximum weight and cost contribution. In such case, developing a system with stack having higher power density reduces overall weight and increases power density (kW/kg). PowerUP Energy Technologies has developed light weight fuel cell stack to achieve higher power density. Experiments considering flow field designs, recirculation strategy, different anode configuration has been a subject of study. Dead-end anode, closed cathode configuration of fuel cell stack further improves fuel utilization. Recirculation line of hydrogen if further added can improve in overall fuel utilization. Counter flow arrangement for reactant distribution further removes the necessity of humidifying the gases. This result in removal of humidifiers and thereby reducing the weight of the fuel cell system in total. Portable fuel cell systems have flexibility for ease in transportation and stationery solutions. Furthermore, lighter fuel cell stacks add advantage for higher output power at lower overall weights. This stack developed is further optimized with improved flow field designs and design of manifold. These fuel cell stacks are used in PowerUP’s portable fuel cell electric generators that are more efficient and sustainable than the currently used fossil fuel based solutions.