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Whereas the common PEM fuel cell, also called Low Temperature Proton Exchange Membrane fuel cell (LT-PEM), must usually be operated with hydrogen with high purity of more than 99.9 % the HT-PEM fuel cell is less sensitive to impurities and thus is typically operated with reformate gas with hydrogen concentration of about 50 to 75 %.
Direct methanol fuel cells or DMFCs are a subcategory of proton-exchange membrane fuel cells in which methanol is used as the fuel and a special proton-conducting polymer as the membrane (PEM). Their main advantage is low temperature operation and the ease of transport of methanol, an energy-dense yet reasonably stable liquid at all ...
Compared to liquid electrolytes, a polymeric membrane has a much lower chance of leakage [2]. The proton-exchange membrane is commonly made of materials such as perfluorosulfonic acid (PFSA, sold commercially as Nafion and Aquivion), which minimize gas crossover and short circuiting of the fuel cell. A disadvantage of fluor containing polymers ...
The fuel cartridge stores the methanol fuel. Depending on the system design either 100% methanol (IMPCA industrial standard) or a mixture of methanol with up to 40 vol% water is usually used as fuel for the RMFC system. 100% methanol results in lower fuel consumption than water-methanol mixture (Premix) but goes along with higher fuel cell system complexity for condensing of cathode moisture.
Demonstration model of a direct methanol fuel cell (black layered cube) in its enclosure Scheme of a proton-conducting fuel cell. A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen) and an oxidizing agent (often oxygen) [1] into electricity through a pair of redox reactions. [2]
A mixture of water and methanol with a molar concentration ratio (water:methanol) of 1.0 - 1.5 is pressurized to approximately 20 bar, vaporized and heated to a temperature of 250 - 360 °C. The hydrogen that is created is separated through the use of Pressure swing adsorption or a hydrogen-permeable membrane made of polymer or a palladium alloy.
An improved generation of General Electric's PEM fuel cell was used in all subsequent Gemini missions, but was abandoned for the subsequent Apollo missions. [9] The fluorinated ionomer Nafion, which is today the most widely utilized proton-exchange membrane material, was developed by DuPont plastics chemist Walther Grot. Grot also demonstrated ...
A dish of ethanol aflame. Various alcohols are used as fuel for internal combustion engines.The first four aliphatic alcohols (methanol, ethanol, propanol, and butanol) are of interest as fuels because they can be synthesized chemically or biologically, and they have characteristics which allow them to be used in internal combustion engines.