The race to 100 mpg
#1
03-18-2007, 10:29 AM
The race to 100 mpg
Over the past several decades, the promise of the "car of tomorrow" has remained unfulfilled, while the problems it was supposed to solve have only intensified. The average price of a gallon of gas is higher than at any time since the early 1980s. The Middle East seems more volatile than ever. And even climate skeptics are starting to admit that the carbon we're pumping into the atmosphere might have disastrous consequences.
To these circumstances, automakers have responded with a fleet of cars that averages 21 miles per gallon, about 4 mpg worse than the Model T.
Yet hope is coming faster than that hydrogen economy you've been hearing about. Several small companies are developing new engine technologies and advanced automotive designs that promise to deliver 100 miles from a single gallon of gas. The proposals run from the simple -- reduce weight, improve aerodynamics -- to the incredible (one company wants to borrow a few tricks from jet engines).
To these circumstances, automakers have responded with a fleet of cars that averages 21 miles per gallon, about 4 mpg worse than the Model T.
Yet hope is coming faster than that hydrogen economy you've been hearing about. Several small companies are developing new engine technologies and advanced automotive designs that promise to deliver 100 miles from a single gallon of gas. The proposals run from the simple -- reduce weight, improve aerodynamics -- to the incredible (one company wants to borrow a few tricks from jet engines).
#2
03-19-2007, 04:30 AM
Re: The race to 100 mpg
By far the most obvious approach to achieving ultra-high mileage is to dramatically cut weight and wind resistance, the chief enemies of highway mileage.
The EPA has built a modified hybrid that uses a hydraulic system, not a battery, to store braking energy. When you press the brakes, the wheels drive a pump that compresses nitrogen gas, which is inexpensive and inert. When you accelerate again, that compressed gas runs the pump in reverse to help power the vehicle.
Based on data from compressor prototypes, Rabroker believes the StarRotor will convert between 45 and 65 percent of the chemical energy in its fuel to mechanical energy, irrespective of the engine's operating speed or power.
In contrast, a typical gasoline engine has a peak efficiency of about 30 percent at full throttle and operates at a much lower efficiency during typical driving conditions.
In contrast, a typical gasoline engine has a peak efficiency of about 30 percent at full throttle and operates at a much lower efficiency during typical driving conditions.
http://www.starrotor.com/Engine.htm
It couples a rotary, displacement compressor with a second one working as a motor and uses a continuous combustion along with an intercooler to recapture exhaust heat. Potentially a clever idea since unlike centrifugal and axial compressors and turbines it could have a wider shaft speed range. But whether or not it makes it into a practical engine remains a question.
A similar engine could be made from a four-stroke engine using rotating valves. It too would be continuous combustion and incorporate an intercooler. However, it would need a different crankshaft with the throws at 90 degrees. However, it would likely be a little heavy for the power output. The same approach could be used with a Wankle.
Understand that I have no problem with these efforts and to a greater or lessor extent, each has merit. However, PowerPoint engineering isn't product and what often looks great on paper doesn't always survive the lab and subsequently make it to manufacturing. Fortunately, there is nothing fundamentally wrong with any of these approaches. Unlike hydrogen power systems, there are fewer "a miracle occurs" moments like this Sidney Harris cartoon:
Bob Wilson
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