Gravimetric power density

An integrated heat exchanger-reactor for methanol steam reforming was developed by Hermann et al. [65] at GM/OPEL for a 50 kW methanol fuel processor. The system specifications included a volumetric power density of more than 5 kW dm, a gravimetric power density of more than 2.5 kWkg and a transient response to load changes from 10 to 90% in milliseconds. 

Serenus H3-350W from Serenergy AS (Fig. 4b) with triple volumetric and double gravimetric power density, respectively, as compared to state-of-the-art direct methanol fuel-cell systems in the same power class, to be used either standalone or in 24 V hybrid battery—fuel-cell systems, (c) Aerospace Industry... 

Although this notion is more difficult to define, we can speak of a gravimetric power density, specifying the conditions of discharge in which that value was obtained. To date, no standard or specification prescribes... 

The peak power over 30 seconds is given as 45 kW. Hence, the gravimetric power density is 150 W/kg. 

Specific power. The amount of electric power a battery can deliver per unit mass at a specified state of charge, which is usually 20%. This quantity is also known as gravimetric power density and is measured in watt per kilogram (W/kg). 

System Voltage Specific energy (gravimetric) Power density Flat discharge profile Low- temperature operation High- temperature operation Shelf life Cost... 

Open circuit volts (V) Volts uiuler load (V) Discharge voltage profile Gravimetric energy density (WhAg- ) Volumetric energy density (Wh/dm ) Gravimetric power density (Wkg )... 

Gravimetric power density (Wkg- ) 130 750-1000 according to cell size... 

For most mobile applications size and weight of the fuel cell is very important. Automotive fuel cell stacks have gravimetric and volumetric power density >1 kW/kg and >1 kW/1, respectively. For smaller stacks <10 kW, power density is significantly lower. 

Arulepp et al. [81] reported an in situ technique of CDC activation whereby Ti02 was mixed with TiC and chlorinated. During synthesis, titanium in the Ti02 was etched, leaving controlled amounts of oxygen to etch the carbon. It was shown that the oxidation treatment improved the volumetric capacitance but not the gravimetric capacitance. This was perhaps because of unreacted Ti02 in the sample. The carbon was ideally polarizable at E < 2.8 V and showed a power density of 2.5kW/kg. 

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