http://www.youtube.com/watch?v=jjSOvbsE460
This video is a couple years old, maybe these are available now?
This video is a couple years old, maybe these are available now?
Two unique compressed air engines
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Originally Posted By: hate2work
http://www.youtube.com/watch?v=jjSOvbsE460
This video is a couple years old, maybe these are available now?
They will NEVER be available. Basic thermodynamics guarantees that fully 50% of the energy you put INTO compressing air simply becomes heat. That means you throw away one half of your input energy before you even start driving a compressed air powered vehicle. Then because the air tries to drop below ambient temperature when it goes through the motor, you lose almost another 50% (of the 50% you have left) getting the energy from the compressed air tank to the motor. And you still haven't started to account for mechanical losses! That's why it takes a 5-horsepower 220V shop compressor to run a cut-off grinder continuously. It makes sense for small shop tools because the tool stays very cool (its where the air is expanding and cooling) and because its spark-free and electrocution-free. It does not make sense for anything bigger than an impact wrench.
"Oh, but wait!" they say. "You can re-compress air during braking and recover energy!" Sure. You can recover HALF of what it takes to brake the car (the rest goes to heat) and then you lose half of the half again when you try to use that air. So in a *PERFECT* scenario, you can actually re-use less than 6% of the energy that first went into the compressor.
Compare that to current internal combustion engines, which can put as much as 40% of the energy in the fuel down to the pavement to drive the car.
Compressed-air vehicles are the dumbest thing since nuclear powered airplanes.
http://www.youtube.com/watch?v=jjSOvbsE460
This video is a couple years old, maybe these are available now?
They will NEVER be available. Basic thermodynamics guarantees that fully 50% of the energy you put INTO compressing air simply becomes heat. That means you throw away one half of your input energy before you even start driving a compressed air powered vehicle. Then because the air tries to drop below ambient temperature when it goes through the motor, you lose almost another 50% (of the 50% you have left) getting the energy from the compressed air tank to the motor. And you still haven't started to account for mechanical losses! That's why it takes a 5-horsepower 220V shop compressor to run a cut-off grinder continuously. It makes sense for small shop tools because the tool stays very cool (its where the air is expanding and cooling) and because its spark-free and electrocution-free. It does not make sense for anything bigger than an impact wrench.
"Oh, but wait!" they say. "You can re-compress air during braking and recover energy!" Sure. You can recover HALF of what it takes to brake the car (the rest goes to heat) and then you lose half of the half again when you try to use that air. So in a *PERFECT* scenario, you can actually re-use less than 6% of the energy that first went into the compressor.
Compare that to current internal combustion engines, which can put as much as 40% of the energy in the fuel down to the pavement to drive the car.
Compressed-air vehicles are the dumbest thing since nuclear powered airplanes.
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You can compress air with higher efficiency if you cool it between compression stages. But the car that runs on it would also have to reheat it as it is expanded, which would require a rather large radiator that might ice up on humid days.
Originally Posted By: 440Magnum
Originally Posted By: hate2work
http://www.youtube.com/watch?v=jjSOvbsE460
This video is a couple years old, maybe these are available now?
They will NEVER be available. Basic thermodynamics guarantees that fully 50% of the energy you put INTO compressing air simply becomes heat. That means you throw away one half of your input energy before you even start driving a compressed air powered vehicle. Then because the air tries to drop below ambient temperature when it goes through the motor, you lose almost another 50% (of the 50% you have left) getting the energy from the compressed air tank to the motor. And you still haven't started to account for mechanical losses! That's why it takes a 5-horsepower 220V shop compressor to run a cut-off grinder continuously. It makes sense for small shop tools because the tool stays very cool (its where the air is expanding and cooling) and because its spark-free and electrocution-free. It does not make sense for anything bigger than an impact wrench.
"Oh, but wait!" they say. "You can re-compress air during braking and recover energy!" Sure. You can recover HALF of what it takes to brake the car (the rest goes to heat) and then you lose half of the half again when you try to use that air. So in a *PERFECT* scenario, you can actually re-use less than 6% of the energy that first went into the compressor.
Compare that to current internal combustion engines, which can put as much as 40% of the energy in the fuel down to the pavement to drive the car.
Compressed-air vehicles are the dumbest thing since nuclear powered airplanes.
Well, THAT was a buzzkill
I'll go and cancel my order for my air compressor car now...
Originally Posted By: hate2work
http://www.youtube.com/watch?v=jjSOvbsE460
This video is a couple years old, maybe these are available now?
They will NEVER be available. Basic thermodynamics guarantees that fully 50% of the energy you put INTO compressing air simply becomes heat. That means you throw away one half of your input energy before you even start driving a compressed air powered vehicle. Then because the air tries to drop below ambient temperature when it goes through the motor, you lose almost another 50% (of the 50% you have left) getting the energy from the compressed air tank to the motor. And you still haven't started to account for mechanical losses! That's why it takes a 5-horsepower 220V shop compressor to run a cut-off grinder continuously. It makes sense for small shop tools because the tool stays very cool (its where the air is expanding and cooling) and because its spark-free and electrocution-free. It does not make sense for anything bigger than an impact wrench.
"Oh, but wait!" they say. "You can re-compress air during braking and recover energy!" Sure. You can recover HALF of what it takes to brake the car (the rest goes to heat) and then you lose half of the half again when you try to use that air. So in a *PERFECT* scenario, you can actually re-use less than 6% of the energy that first went into the compressor.
Compare that to current internal combustion engines, which can put as much as 40% of the energy in the fuel down to the pavement to drive the car.
Compressed-air vehicles are the dumbest thing since nuclear powered airplanes.
Well, THAT was a buzzkill
I'll go and cancel my order for my air compressor car now...
Supposedly compress air car is very cheap to make, much cheaper than combustion/electric hybrid in providing regenerative braking.
Until you factor in the crash worthiness, weight, acceleration requirement, compression storage duration (and efficiency) of a design that will suit a developed nation, then you realized that it is very ineffective.
In a way, you can say that it is like an electric assisted scooter for the US market. Will it do the job that most people need? Sure, but why on earth will people buy it when a used compact car here only cost the equivalent of 1-2 month's salary before tax and can last you 4-5 years?
The last thing you want is to run out of compressed air because the weather is too cold and you have to call an Airgas truck to pump you up before you can get back home.
Until you factor in the crash worthiness, weight, acceleration requirement, compression storage duration (and efficiency) of a design that will suit a developed nation, then you realized that it is very ineffective.
In a way, you can say that it is like an electric assisted scooter for the US market. Will it do the job that most people need? Sure, but why on earth will people buy it when a used compact car here only cost the equivalent of 1-2 month's salary before tax and can last you 4-5 years?
The last thing you want is to run out of compressed air because the weather is too cold and you have to call an Airgas truck to pump you up before you can get back home.
All that company has accomplished in 15 years is to issue press releases and take investors money.
This blurb from a Popular Mechanics reader will save me a lot of typing.
Quote:
871. Air car fraud
MDI, the company that sells licenses to manufacture the air car is in the business of issuing press releases and obtaining investors. If you look at the past history of MDI you will see that all that they managed to accomplish over the last 15 years is obtaining free advertisement for the air car from media that love a sensational story. If those in the media bothered to look into the claims by MDI and had them reviewed by a person knowledgeable in the field of thermodynamics, it would be apparent that the claims are not credible. There are limits to what is possible with a specific amount of energy, MDI fraudulently claims performance figures well beyond the limits. The media does a great disservice to their readers and viewers by accepting the press releases and claims from MDI without question. A review of the history of MDI, starting with the credentials of Mr Negre will make it quite apparent the company claims whatever is necessary to hype itself, and garner free publicity to entice new investors. There will be many disappointed investors, that should have elicited independent review of what was claimed, they will learn a lesson and MDI will, by virtue of the language in their contracts laugh all the way to the bank. The greed of the investors in pursuit of riches will be their downfall.
http://www.popularmechanics.com/automotive/new_cars/4217016.html
This blurb from a Popular Mechanics reader will save me a lot of typing.
Quote:
871. Air car fraud
MDI, the company that sells licenses to manufacture the air car is in the business of issuing press releases and obtaining investors. If you look at the past history of MDI you will see that all that they managed to accomplish over the last 15 years is obtaining free advertisement for the air car from media that love a sensational story. If those in the media bothered to look into the claims by MDI and had them reviewed by a person knowledgeable in the field of thermodynamics, it would be apparent that the claims are not credible. There are limits to what is possible with a specific amount of energy, MDI fraudulently claims performance figures well beyond the limits. The media does a great disservice to their readers and viewers by accepting the press releases and claims from MDI without question. A review of the history of MDI, starting with the credentials of Mr Negre will make it quite apparent the company claims whatever is necessary to hype itself, and garner free publicity to entice new investors. There will be many disappointed investors, that should have elicited independent review of what was claimed, they will learn a lesson and MDI will, by virtue of the language in their contracts laugh all the way to the bank. The greed of the investors in pursuit of riches will be their downfall.
http://www.popularmechanics.com/automotive/new_cars/4217016.html
Originally Posted By: Shannow
I can understand using such for a forklift in a warehouse at a power station...not for transport
Worked on a program that briefly considered compressed air cars for light duty transportation in coal mines. Mechanics, foremen etc. It just made a lot more sense to use battery power, even in that environment.
I can understand using such for a forklift in a warehouse at a power station...not for transport
Worked on a program that briefly considered compressed air cars for light duty transportation in coal mines. Mechanics, foremen etc. It just made a lot more sense to use battery power, even in that environment.
It might work for a scuba diving propulsion assist since you already need compressed air.
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