MDI / Tata Air Car
See also an air car from MDI / Tata
http://www.technologyreview.com/Energy/20071/
See also an air car from MDI / Tata
http://www.technologyreview.com/Energy/20071/
Yes, those are exactly the right questions to ask, and compared to batteries, it is less efficient in all the aspects you list. The benefit of this approach over batteries, is that a pressure tank can be rapidly refilled, whereas, today's batteries require at least 4 hours to achieve an 80% recharge, which causes the "range anxiety" that turn car buyers off from buying 100$ BEV's.While I do think the rotary air engine itself is a cool device, I would be very surprised it it would be reasonable for this application. The big issues are, how much energy can you store in say a one cubic meter volume? What is the efficiency of converting that stored energy to mechanical energy? What is the expected energy loss from heat flow out of the pressurized tank? Can you recover mechanical energy from the cars motion and re-pressurize the tank? What is the efficiency of that?
These things need to be answered before the air engine can be reasonably compared. Besides it will take energy to compress the air to begin with, which will likely have to come from electric or chemical energy.
One of the feature of using a battery or capacitor is the efficiency of energy storage and conversion, both in terms of unit mass and unit volume.
I don't mean to sound like a jerk, but at first glance, this device doesn't appear to accomplish the desired goals.
Your crazy idea is now a start-up:I think it's clear that an air powered engine is a winner - the issue, as with an electric motor, is the energy storage. The MDI / Tata article above mentioned an on-board motor to recharge the compressed air tank, much like the ICE generator on the Volt.
So here's the crazy idea - instead of a piston ICE driving a compressor, how about direct injection of fuel & oxidizer into the compressed air tank? I don't know enough to say what would the burn be like under high pressure. But if it does burn cleanly, I can't think of a more efficient way to recharge the pressure, if you're going to use liquid fuel.
I did see that, and thought "my crazy idea is now a start-up". Instead of burning the fuel *inside* the tank, as I had proposed, they have a separate chamber between the tank and the rotary engine. This allows combustion at lower pressures.Your crazy idea is now a start-up:
http://zeropollutionmotors.us/
They burn fuel to heat the compressed air, getting crazy range and mileage over compressed air alone.
Just to clarify, in this thread, we're talking about a car that uses compressed air instead of a battery, to drive an engine that runs on compressed air. The range-extender part comes in when you burn fuel, and use the exhaust gases to drive the same engine.So, at least to me, using compressed air as an RE is as useful to me as not having an RE at all.
Modern Marvels, or one of those other type shows, showed that a carbon fiber tank would just tear along a seem, instantly bursting all its pressure at once with no shrapnel. Even metal tanks would burst all at once at those pressures.I'm not sure that a compressed air tank is as safe as a battery. The issue is how fast the energy is released in a crash situation. A compressed air tank would become a rocket.
However, I'm sure that there are ways around this problem!!!! For instance, in addition to a strong outer shell, the compressed air tank could be filled with some kind of air-permeable foam material that has very high tensile strength. If the outer shell were breached, this inside material would limit how fast the air could be released.
I think the rotary air engine would make a great range extender. If you connect the rotary motor shaft to a generator shaft, you could produce a smooth flow of electricity to maintain a charge in the batteries, and the batteries could quickly handle various loads on the vehicle.Great find Jason!
What a great video.
I like the rotary engine better...I think it could be quieter,more reliable and have better low end torque. Maybe similar to an electric motor?
Although the MDI concept of preheating the air to increase pressure using petro is also really good. Did they infer something like 900 miles on one tank of gas and air?
Seems like a viable concept...