September 1, 2006 Engineers at a national lab have shown that small fans embedded in car seats could help cool passengers down -- saving up to 7 percent of the 30 to 40 gallons of gasoline per year an average driver consumes for powering air conditioning systems. The engineers are also studying ways to power A/C by converting some of the engine's heat into sound waves first.
GOLDEN, Colo. -- The average driver uses 30 gallons to 40 gallons of gasoline each year just running the car's air conditioning. That adds up to seven billion gallons of gas annually. At the Department Of Energy's National Renewable Energy Lab, engineers are researching ways to cool the people in the car rather than the entire car.
ADAM, the hot, sweaty manikin, reveals more about feeling comfortable than a living, breathing human being could. While he can't talk, ADAM can perspire when it's hot and shiver from the cold. Right now it's 90 degrees inside ADAM's car.
"He's uncomfortable right now. We just put him in the car, and it's been soaking. It's hot, but as the air conditioning cools the car down, ADAM will start feeling more comfortable," John Rugh, a project leader at NREL in Golden, Colorado, tells DBIS.
This test would be torture for a person, but for ADAM it's a no-brainer. Mechanical engineers at NREL are researching ways to reduce gasoline consumption while increasing passenger comfort. First, solar reflective glass keeps the parked car cooler when passengers first get in. Then, small fans in ventilated seats pull hot air away from the seat's surface.
According to Rugh, the ventilated seats pull air through your clothing, causing your sweat to evaporate and using the body's natural mechanisms to cool itself. Also, thanks to acoustics the engine's excess heat is put to work cooling the inside of the car.
NREL mechanical engineer Matt Keyser says, "Essentially what thermal acoustics is, is you take heat and you convert the heat to sound, and then you use the sound to cool."
They estimate if all passenger vehicles had ventilated seats alone that would save 7 percent of fuel used for air conditioning. And reducing the amount of fuel used for AC by 7 percent a year would save 522 million gallons of gasoline a year in the United States.
BACKGROUND: Researchers at the Department of Energy's National Renewable Energy Lab are working with industry to try to reduce fuel consumption from air conditioning use in cars and trucks, by improving the comfort level inside the cars in a variety of new ways. The team at NREL has already demonstrated that car seats with a little fan inside can improve a vehicle's fuel economy while improving passenger comfort. That's because ventilated seats keep drivers and passengers cooler, so they need less air conditioning to be comfortable. The NREL estimates that if all passenger vehicles had ventilated seats, it would result in a 7.5 percent reduction in the use of fuel by the air conditioning system, saving an estimated 552 million gallons of fuel each year.
OTHER STRATEGIES: The researchers are also testing such options as reflective glass insulation, different seat materials, and modifying the angle of the air flow. They are conducting the tests with a "human thermal comfort manikin" named ADAM. ADAM is a surface sensor shaped like a human body that measures heat loss. ADAM is a test dummy that can "sweat" and "shiver" to simulate the internal heat systems in the human body and how a body changes in response to heat or cool. This data is fed into a computer, which can use it to predict human thermal comfort based on these simulated "skin temperature" measurements.
HOW A/C WORKS: An air conditioner works on the same principle as a refrigerator, without the insulated box. Freon gas (or a similar refrigerant) is compressed, causing it to heat up and its pressure to rise. The hot gas runs through a set of coils, dissipating its heat so that it condenses into a liquid. The now-liquid Freon runs through a special valve that causes it to evaporate back into cold, low-pressure gas, and this cold gas runs through another set of coils. Because heat always flows from a hotter to a colder region or object, the gas will absorb heat and thereby cool down the surrounding air.
COOL CARS: All cars come with a built-in cooling system. That's because gasoline engines are quite inefficient at converting chemical energy into mechanical power. Most of that energy (70 percent) is converted into heat. The cooling system keeps the engine from overheating by transferring the heat into the air.
The Institute of Electrical and Electronics Engineers, Inc., contributed to the information contained in the TV portion of this report.