Topic
Power density
About: Power density is a research topic. Over the lifetime, 9534 publications have been published within this topic receiving 197264 citations. The topic is also known as: volumic power & volume power density.
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TL;DR: In this article, the power density, defined as the ratio of power output to maximum specific volume in the cycle, is taken as the objective for performance analysis of an endoreversible closed Brayton cycle coupled to variable temperature heat reservoirs in the viewpoint of finite time thermodynamics or entropy generation minimization.
60 citations
TL;DR: The plate-shaped gold anodic electrode in the mini-MFC showed a higher electrochemical activity than the stripe-shaped one and a biofilm of Shewanella oneidensis MR-1 was formed on the surface of gold electrode in this micro-liter-scale MFC.
60 citations
TL;DR: In this article, an asymmetric supercapacitor operating at 1.8 V was constructed using MnFe 2 O 4 /graphene as anode and MnO 2 /carbon nanotube as cathode.
60 citations
TL;DR: In this article, a 40nm-thick ex-situ silicon nitride passivation layer was added to nitrogen-polar gallium nitride (GNT) transistors to improve the dispersion control.
Abstract: This letter reports on the improvement of the large-signal W-band power performance of nitrogen-polar gallium nitride deep recess high electron mobility transistors with the addition of a 40-nm-thick ex-situ silicon nitride passivation layer deposited by plasma enhanced chemical vapor deposition. The additional passivation improves the dispersion control allowing the device to be operated at higher voltages. Continuous-wave load pull measurements performed at 94 GHz on a $2\times 37.5\,\,\mu \text{m}$ transistor demonstrated an improvement in the peak power-added efficiency (PAE) to 30.2% with an associated output power density of 7.2 W/mm at 20 V drain bias. Furthermore, at 23 V, a new record-high W-band power density of 8.84 W/mm (663 mW) was achieved with an associated PAE of 27.0%.
60 citations
TL;DR: In this article, a membrane-less hydrogen-air fuel cell with mesoporous carbon electrodes was investigated with the aim of establishing a strategy for raising volume power density, the measure of importance for miniature devices.
Abstract: The unusual ability of O2-tolerant hydrogenases (H2ase) to produce electricity from a H2–air mixture (when used as the anodic electrocatalyst in a simple, membrane-less fuel cell) is investigated with the aim of establishing a strategy for raising volume power density, the measure of importance for miniature devices. Compacted mesoporous carbon electrodes provide a simple and inexpensive method for obtaining a large increase in productive enzyme loading, greatly increasing current densities and stability. Operated under a 78% H2–22% air mixture at 25 °C, typical current densities at a stationary H2ase anode and bilirubin oxidase cathode are 4.60 ± 0.32 mA cm−2 and 1.23 ± 0.12 mA cm−2, respectively. The power limitation due to low O2 concentration is addressed by re-proportioning the cathode/anode area ratio to balance the cathodic and anodic currents. At room temperature, the maximum power density of the fuel cell with an anode/cathode (A/C) ratio of 1 : 3 (1A/3C) is 1.67 ± 0.24 mW cm−2 (per anode area) or 0.42 ± 0.06 mW cm−2 (per total area). Good prospects for stability are demonstrated by the fact that 90% of the power is retained after continuously working for 24 h, and more than half of the power is retained after one week of non-stop operation. Using an even weaker O2 mixture (89% H2, 11% air) the 1A/3C cell gives over 0.8 mW cm−2 (anode) or 0.2 mW cm−2 (total electrode area). The results demonstrate the feasibility of membrane-less hydrogen–air fuel cells delivering volume power densities well in excess of 1 mW cm−3.
60 citations