Read Online The Twelve Kingdoms, Volume 1: Sea of Shadow Book Directory PDF
-
*Link Download The Twelve Kingdoms, Volume 1: Sea of Shadow Free EBook,PDF
and Free Download PDF*
Read Online The Twelve Kingdoms, Volume 1: Sea of Sh...
3 years ago
Posts
2 comments:
The problem with schemes like this is simply: what is the life-cycle energy efficiency? Releasing the high pressure air through an engine to do work can be fairly efficient if the initial pressure is high enough. But charging that air to high pressure is another matter indeed. The maximum energy efficiency of such a scheme is probably in the order of 15-20%. Not very good against current fuel efficiency standards, and certainly much less efficient than converting the fuel energy directly into mechanical energy in a diesel engine. The most efficient engines currently existing are the large piston diesel engines on container ships. These run near 50% efficiency.
Continuing:
Put another way, I have a fairly good 1 1/2 HP air compressor at my house which I use for various things. One of the tools I have is an air powered die grinder. This tool has about twice the power of a Dremel tool, which is about 1/16 HP (100 watts). Yet the air compressor can only run the die grinder at about 30% duty cycle. So, the energy efficiency of the air pressure conversion to useful work at about 10%, not counting the fact that the electric power cycle efficiency (from the original fuel) is about 35%. A good electric motor is about 95% efficient.
There is a way to obtain fairly high compressor efficiency, and that's in a jet engine. There, the heat of compression is captured and turned into useful work in the combustion process. The most fuel efficient power plants are "combined cycle" plants which employ an aero-derivative gas turbine engine with a heat recovery boiler/ steam turbine running off the turbine exhaust. These plants are better than 55% efficient.
So, I think this idea of running an automobile from compressed air isn't nearly as good as a hybrid car (which recovers much energy from regenerative braking), and not even as environmentally friendly.
It's just a bunch of hot air.
Post a Comment