Ultra-Efficient Gas Engine Passes Test — Diesel-like Performance of 64 MPG
Source: MIT Technology Review
Transonic Combustion, a startup based in Camarillo, CA, has developed a fuel-injection system it says can improve the efficiency of gasoline engines by more than 50 percent. A test vehicle equipped with the technology gets 64 miles per gallon in highway driving, which is far better than more costly gas-electric hybrids, such as the Prius, which gets 48 miles per gallon on the highway.
The key is heating and pressurizing gasoline before injecting it into the combustion chamber, says Mike Rocke, Transonic’s vice president of business development. This puts it into a supercritical state that allows for very fast and clean combustion, which in turn decreases the amount of fuel needed to propel a vehicle. The company also treats the gasoline with a catalyst that “activates” it, partially oxidizing it to enhance combustion.
I am generally leery of any new fuel efficiency technology that requires any additive that “activates” or “catalyzes” anything… but it’s very interesting that this new injection system does not require a spark-plug for ignition, instead injecting fuel directly into the combustion chamber and allowing the heat generated during compression ignite the fuel – much like a diesel engine. (Fun fact: The current crop of small diesel engines available in Europe are regularly scoring 60+ MPG in every-day driving.)
Once the fuel is injected into the piston, the heat and pressure are enough to cause the fuel to combust without a spark (similar to what happens in diesel engines), which also helps provide fast, uniform combustion. Ignition can be timed to happen just when the piston is reaching the optimal point, so it can convert as much of the energy in the gasoline into mechanical movement as possible, without wasting energy by heating up the combustion chamber walls, as happens in conventional technologies. The company has developed proprietary software that lets the system adjust the injection precisely depending on the load put on the engine.
So is this new injection technology a way to use the diesel cycle with widely available gasoline instead? Considering that refineries generally produce much more gasoline vs. diesel from each barrel of oil, this technology might allow us to take advantage of the diesel-engines superior efficiency without off-setting the gas/diesel ratios of production and distribution. Like modern (and prototype) FLEX-fuel engines, this new technology would allow drivers to “work within” our existing “gas station” distribution model, without requiring expensive new “refueling stations” or specialized refining and distribution networks that do not currently exist in any great numbers.
With gasoline prices generally unstable and on the rebound since the “crash” of 2008, modern mobile civilizations are counting on engineers to innovate creative solutions like this one.
“It’s a time of renaissance for internal combustion engines,” says William Green, a professor of chemical engineering at MIT.
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