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In a special boiling cell, vapor bubbles are generated at single nucleation sites on top of a 20μm thick stainless steel heating foil. An infrared camera captures the rear side of the heating foil for analyzing the temperature distribution. The bubble shape is recorded through side windows with a high-speed camera. Global measurements were conducted, with the pure fluids FC-84 and FC-3284 and with its binary mixtures of 0.25, 0.5, and 0.75mole fraction. The heat transfer coefficient (HTC) in a binary mixture is less than the HTC in either of the single component fluid alone. Applying the correlation of Schlünder showed good agreement with the measurements (1982, “Über den Wärmeübergang bei der Blasenverdampfung von Gemischen,” Verfahrenstechnik, 16(9), pp. 692–698). Furthermore, local measurements were arranged with high lateral and temporal resolution for single bubble events. The wall heat flux was computed and analyzed, especially at the three-phase-contact line between liquid, vapor, and heated wall. The bubble volume and the vapor production rate were also investigated. For pure fluids, up to 50–60% of the latent heat flows through the three-phase-contact region. For mixtures, this ratio is clearly reduced and is about 35%.

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The big challenge of global phase-down of carbon dioxide emissions leads us to alternatives in storing electric energy from renewable sources. For the worldwide use of batteries and fuel cells very high amounts of precious electrode materials are needed. Batteries require rare earth metals and environmentally harmful Lithium, PEM fuel cells require noble platinum and iridium. Thus, an economical and eco-friendly alternative to lithium-ion-batteries should be found, especially for the use in domestic homes. In the on-hand work, a well-known type of fuel cell is revised and considered in the new context of global material usage. Therefore, an alkaline fuel cell with the classic design of an electrolyte gap inbetween the electrodes is observed. Gas-diffusion-electrodes are used, based on Raney-nickel. Results are given for different catalysts: Raney-nickel, Raney-silver, manganic-oxide, carbon and ruthenium. For the analysis current-voltage-characteristics, chronopotentiometry and SEM micrographs are used. The results are discussed in comparison to a unitized reversible PEM fuel cell. At low current density, the alkaline cell is obtaining round-trip efficiencies close to 70%, while the PEM cell achieves only 60% efficiency. With Silver-catalyst clear higher efficiencies up to 80% are presentable. The PEM fuel cell shows obvious better performance at high current densities.