Ratio Power to weight

Solar cells have been used extensively and successfully to power sateUites in space since the late 1950s, where their high power-to-weight ratio and demonstrated rehabiUty are especially desirable characteristics. On earth, where electrical systems typically provide large amounts of power at reasonable costs, three principal technical limitations have thus far impeded the widespread use of photovoltaic products solar cells are expensive, sunlight has a relatively low power density, and commercially available solar cells convert sunlight to electricity with limited efficiency. Clearly, terrestrial solar cells must be reasonably efficient, affordable, and durable. International efforts are dedicated to obtaining such devices, and a number of these activities have been reviewed (1). 

Power-to-weight ratios Moderate Moderate High... 

Hydraulie aetuators are employed in sueh areas as the aerospaee industry beeause they possess a good power to weight ratio and have a fast response. 

PEM fuel cells are used primarily for transportation applications and some stationary applications. Due to their fast start-up time, low sensitivity to orientation, and favourable power-to-weight ratio, PEM fuel cells are particularly suitable for use in passenger vehicles, such as cars and buses. 

The key achievements at Ballard (Wilkinson 1998)15 are low Pt loading (1 mg cm-2) in 50-kW fuel cell power plants, and that of a power-to-weight ratio of 1 kW/kg. The development of the solid polymer electrolyte membrane was by no means in a final state in the late 1990s. The quality of the membrane controls the highest current density at which the cell is viable. There are open areas, too, with regard to the composition (as apart from the loading and particle size) of the catalyst a PtRu alloy... 

Historically, the two-stroke engine has been a dominant force in the world of motorcycling and portable equipment due to its high power-to-weight ratio, simplicity of construction and low cost compared to equivalent sized four-stroke engines. 

From the outside, few people buying a modern car realize the extent to which plastics contribute to the good power to weight ratio and low fuel consumption that we have grown to expect. In the future we can expect to see car bodies completely made of plastic. 

Finally, FCs produce negligible noise since they have neither moving parts nor intermittent irreversible reactions (like combustion or explosion). They can have high power-to-weight ratios (up to 0.7 kW/Kg) and power density (up to 1 kW/litre). 

The development of new membranes by Dupont and Dew Chemicals recently granted a very sharp increase in current density, that is, from the "conventional" 200 mA/cm to 4 A/cm. This success obviously reflects onto power density and power-to-weight ratio, and has recently allowed a two-person submarine to be equipped, which can be visited in operation in Florida. With this power source, the range of the submarine was increased by a factor 11. 

Used in space missions (high power-to-weight ratio)... 

High power-to-weight ratio, which is very beneficial in an offshore situation. 

Their poor power-to-weight ratio means that the structures supporting them would need to be much larger and stronger. 

They address, e.g., the minimum wall thickness of a beer bottle, the power to weight ratio of a motorcycle, or the nominal size plus tolerance of a shaft in a subassembly. In general, technical specifications express quantitative or easily quantifiable demands. 

Last but not least, the customers are expecting from a fuel ceU vehicle performance on the same level as conventional ones. System power, dynamics, power to weight ratio as well as maximum speed are key elements for the performance feeling. The subjective comfort of the passengers and the environment is influenced by the not to be underestimated effect of the noise-vibration-harshness performance. 

Both types of generators are usually powered by the heat produced by plutonium-238, which has an optimal thermal power to weight ratio (= 0.57 W g- ). 

---