The Air Car

Scott McNally

Chemical Engineering

The University of Texas

Fall 2007

Outline

• The Cars

• Air Tanks

• Thermodynamics – Does it make sense?– Is it even possible?

• Summary and Conclusion

The Engine

• Compressor efficiency: 80-90%

• These engines are compressors in reverse

MDI: Moteur Developpment International

• Weight: 750 Kg• Max load: 500 Kg• Range: 150 miles• Top speed: 68 mph• Recharge time: 3

minutes

Filling the Tanks

• Costs $2 in electricity

• Filling stations– 3 minutes using volume transfer– These stations don’t exist

• Home compressor– 4 hrs in Europe– 8 hrs in U.S.

Thermodynamics

• 300 Liters at 300 Bar– Full tank weight: 200 Kg– 43,600 Btu required for filling– 40,000 max output

• Gasoline: 110,000 Btu/Gal

• Equivalent: 0.4 gallons of gasoline

Thermodynamics

• Honda Civic Hybrid: 45 mpg, 1100 kg– Gas engine: 20% efficient

• At 100% efficiency: 225 mpg

• 0.4 gallons: 90 miles

• Advertised numbers are flawed

• Tank size needs to be doubled– Increase weight by 200 kg– Not a big deal

Thermal Efficiency

• High thermal efficiency– Power plant: biggest loss at 50%– Transmission line loss: 7%– Compressor: 10-20%– Air engine with regenerative braking: 170%

• Impossible

– Overall efficiency: 40% – Electrical efficiency: 70%

Summary - Benefits

• Cheap– 3,500 euro sticker price– A few dollars to fill up and maintain– Free Air Conditioning

• Higher thermal efficiency

Summary - Drawbacks

• Less safe: Fiberglass and glue

• Low power, tank bleed off

• Shorter range

• Infrastructure problem

Conclusion

• Possible

• Good for city driving

• Short range forever

• Not likely to be successful in U.S.

References

• The Air Car. 2007. Moteur Developpment International. 17 Nov. 2007 <http://www.theaircar.com/>. The

• World’s First Air Car. 2007. Popular Mechanics. 17 Nov. 2007 <http://www.popularmechanics.com/automotive/new_cars/42...>.

Questions?