Author Topic: the future of car engines? (Read 2202 times)

rabbidrabbit · « **on:** November 04, 2006, 10:08:10 AM »

http://www.dpccars.com/car-movies/09-25-06page-Air-powered-car.htm

Gee... do you really want a comment? If you watched the video you would know there was no troll except the one who lives under the bridge fragging stuff pointlessly.

There are a couple of youtube shows on how air engines are being developed that might very well change energy use in the US. It looks pretty promising but is it for real?

stantond · « **Reply #1 on:** November 04, 2006, 10:35:58 AM »

I always thought those 'air hog' toys were pretty cool. The concept works, much just like a kit toy stirling engine . Making it useful for much else is a pretty big challenge. I always liked the gas turbine engine cars from the 50's since they could run on about any liquid fuel that would burn and also because that was the engine in the batmobile.

Fwiw, I have precharged pneumatic (PCP) rifle which operates on 3000 psi air. It's fun and almost practical. Originally, the PCP was a British invention.

Regards,

Malta

rabbidrabbit · « **Reply #2 on:** November 04, 2006, 10:40:09 AM »

what I don't get is how they are as efficient as they seem to be now.

Captain Virgil Hilts · « **Reply #3 on:** November 04, 2006, 10:46:39 AM »

Quote

Originally posted by rabbidrabbit
what I don't get is how they are as efficient as they seem to be now.

You have to understand that it is not in a car like you are used to. It's in a very light stripped down car, and with only one person in it. And it still doesn't have the same performance as even a small low powered economy car like you are accustomed to.

rabbidrabbit · « **Reply #4 on:** November 04, 2006, 10:49:06 AM »

I'm guessing it all comes down to storing enough compressed air to give something marketable enough range. If you can pull that off it might be efficient enough to work. That being said, is it any better than an electric car?

Chairboy · « **Reply #5 on:** November 04, 2006, 10:57:26 AM »

Where does the compressed air come from? What creates the power that runs the compressor? Same question the hydrogen car folks need to answer.

eagl · « **Reply #6 on:** November 04, 2006, 11:06:56 AM »

The compressed air comes from captive librules locked in the trunk with masks over their faces and a snapshot of Pres Bush taped in front of them. They just can't help themselves and a steady stream of compressed hot air spews forth. I heard that's why Nash was gone for a while... He was the trunk librule during recent testing, explaining the dramatic increase in compressed air capacity.

mora · « **Reply #7 on:** November 04, 2006, 11:16:20 AM »

I don't think it would be a very efficient battery. Lots of losses in converting electricity to compressed air. Perhaps not as much as in the case hydrogen fuel-cells

rabbidrabbit · « **Reply #8 on:** November 04, 2006, 11:28:42 AM »

the question comes down the most cost effective fuel. Just because it runs on compressed air does not mean it will be cheaper per mile. They do seem to be saying that is the case though...

Angus · « **Reply #9 on:** November 04, 2006, 11:45:56 AM »

Quote

Originally posted by Chairboy
Where does the compressed air come from? What creates the power that runs the compressor? Same question the hydrogen car folks need to answer.

Getting into the Hydrogen question it means that you're using roughly he same energy as with a combustion engine. However, there are way better means of controlling the pollution in the business.
All cars with hydrogen = same energy used, but no city smog.

stantond · « **Reply #10 on:** November 04, 2006, 11:57:56 AM »

The problems with pneumatic, spring, and flywheel cars are weight vs energy storage, safety, and cost. Also thermal energy (from burning something) has to be converted to electrical energy then mechanical energy to operate a compressor, or wind a spring, or spin a flywheel. That means any of these devices have a lower total efficiency than an electric car. However, that may not make them impractical. Most US appliances have much lower efficiency than their European counterparts but work just fine and are quite practical.

Practicality comes from having something that can do the job safely, inexpensively, simply, and in a wide range of conditions. Practicality stops many things from happening including lead acid battery electric cars. Safety is a significant concern with a compressed gas car and compressed air is (relatively) expensive. Also, air motors (that convert pressurized air to mechanical motion) are not efficient. However, compressed air motors are ideal for some emergency systems.

While the off road remote control air powered toy car is cool, having a massive air compressor to refill the equivalent full size car would not be cool and having a large volume high pressure pressure vessel creates conditions for an explosion. For example, when pressure testing tanks with air or another compressed gas a separate calculation for the equivalent amount of TNT is done. This then gives a blast radius which must be observed.

As most people experience, there is no practical alternative to the modern internal combustion engine. If electric batteries were better for use in cars then electric cars would be used. Currently, batteries and so called "Super capacitors" need improvement and may never be practical due to cost.

It's possible to make a compressed air car, but who wants 5000 psi composite air tanks behind them? Not me. Also as compressed air is used, it cools which may be desired in summer but is unwanted in winter. As technology improves, compressed air cars may become more practical with better air tanks, compressors, and air motors.

The bottom line; compressed air cars are possible, but they are not efficient or practical.

Regards,

Malta

Chairboy · « **Reply #11 on:** November 04, 2006, 12:22:06 PM »

I think your assertion that the electric car is more efficient than any other is a bit off. Chemical batteries have very low efficiencies, a significant portion of the power is lost to heat. It's possible that flywheel or compressed air would be more efficient than electric, but it depends on the systems in between.

Pure electric=not very efficient.
Internal combustion=not very efficient

The risk of explosion with the tanks is pretty darn low, these prototypes use carbon fiber wound tanks that are much more likely to simply leak than explode.

Maverick · « **Reply #12 on:** November 04, 2006, 02:30:49 PM »

Explosion chances would be enhanced by collision.

Angus · « **Reply #13 on:** November 04, 2006, 02:45:04 PM »

This:
"As most people experience, there is no practical alternative to the modern internal combustion engine. If electric batteries were better for use in cars then electric cars would be used. Currently, batteries and so called "Super capacitors" need improvement and may never be practical due to cost.
"

"Practical" is a money question, the money question depending on setups like taxing, resources etc.
Then you're into politics. They and the setup outcome do indeed decide what is in that case "practical" or not.
Som in Brazil, it is practical to use biomass to make ethanol for fuel, - in the USA not so.
In Europe it is getting practical to grow rape for the oil, - the main product being biodiesel, - the byproduct is cattlefood.
But I am still stuck with a combustion engine.
Well, in Iceland by now, we use hydro-powered buses and they're doing just fine

mora · « **Reply #14 on:** November 04, 2006, 03:04:46 PM »

Quote

Originally posted by Angus
Well, in Iceland by now, we use hydro-powered buses and they're doing just fine

I'm sure you realize that hydrogen is just a very inefficient battery. Doesn't matter in Iceland though, as you have an abudancy of free energy. The only advantage a hydrogen car has over an electric car is the lower charging time.