Vehicle efficiency energy output

We are interested in the traction chain of a small electric vehicle (segment A), whose efficiency (from the output of the electricity storage devices to the wheels) is assumed to be constant, equal to 0.8. Besides this efficiency, this vehicle s energy consumption is assumed to be served exclusively by aerodynamic friction, rolling friction and the onboard auxiliaries (particularly the air conditioning). 

Vehicle fuel economy is normally measured in miles per gallon. At any given instant, it depends on the energy content of a gallon of fuel (Qf), the vehicle velocity (V.,) and power required (P,-5q), the thermal efficiency with which the engine converts fuel energy into useful output work (rj,.), and the mechanical efficiency with which the driveline delivers that work to the vehicle wheels (r j). Specifically,... 

Fuel cells have attracted considerable interest because of their potential for efficient conversion of the energy (AG) from a chemical reaction to electrical energy (AE). This efficiency is achieved by directly converting chemical energy to electricity. Conventional systems burn fuel in an engine and convert the resulting mechanical output to electrical power. Potential applications include stationary multi-megawatt power plants, battery replacements for personal electronics, and even fuel-cell-powered unmanned autonomous vehicles (UAVs). 

After the invention of a novel membrane electrolyte, the output power density of a PEFC has improved, and fuel cells can be applied to electric vehicles, stationary power sources, and mobile applications such as laptop computers and cellular phones. The high efficiency of the energy conversion of stationary fuel cells would be an important feature considering the limited resources of fossil fuels and their global warming effect. 

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