How can heat management be optimized in compressed air powered bikes?

[Hari Mechie]

hey mechies,

i know "compressed air powered bike" is one of the oldest concept of our engineers but still in their developing stage..

i am in my final year of mechanical engineering undergraduate course. And i am about to do final project by end of this year.. when searching for real time problems my mind strikes on compressed air. the compressed air stored in a container have kinetic energy which can be used in engine to convert it into useful mechanical power.

i thought of using four stroke single cylinder engine. replacing its cam mechanism with solenoids for valve actuation. now the engine will probably a two stroke engine.

but i got strucked in the place tat is tat pressure of air can be used to move the piston downward (as the engine is going to be used in a two wheeler)...?
please post ur valuable suggestion so that let's make our environment clean..!
with regards
hari prasad

 

[jedishrfu]

some info on pneumatic motors:

http://en.wikipedia.org/wiki/Pneumatic_motor

 

[tygerdawg]

compressed air stored in a container have kinetic energy

Actually, that would be potential energy.

so that let's make our environment clean..!

It takes energy to compress the air, and a lot of it. Are you certain you are not simply moving the emissions from the vehicle to the power plant?

You need to do a work/energy analysis. Typical compressed air pressures have limited capacity for power, especially to move a vehicle for any useful distance. In order to get higher pressures, you would need heavier compresssed air plumbing, tanks, motors, etc., thus making the vehicle heavier, thus requiring more power. That is why gasoline & diesel engines are so useful.

 

[etudiant]

Engineering compressed air propulsion is also an exercise in heat management.
Compressing air does a lot of work on it, so it heats up.
However, the compressed air tank will want to be at ambient temperature, so there is need for a heat exchanger when charging the tank.
More problematically, the expansion of the air being tapped from the tank to run the engine will cool the air dramatically, to the point that ice will form on the fittings.
Chilling the air makes it contract, so the cooling cuts the operating efficiency of the setup.