Yet another automotive gas-electric hybrid technology looms
Purdue mechanical engineering student Yaguo Wang works with a high-speed laser at the Birck Nanotechnology Center to study thermoelectric generators (Photo: Purdue/Mark Simons)
The energy crisis has certainly catalyzed a great deal of thought about how we harvest all that energy we previously wasted. The petroleum-burning internal combustion engine has traditionally leaked energy from the exhaust system in the form of heat, but new ThermoElectric Generator (TEG) research at Purdue University aims to yield as much as a ten percent reduction in fuel consumption by converting heat from the exhaust into electricity. It is hoped that the thermoelectric research will eventually lead to other methods of turning waste heat into electricity in homes and power plants, new and more efficient solar cells and perhaps even a solid-state refrigerator.
The project begins on January 1 and will be led by Purdue professor of mechanical engineering and electrical and computer engineering Xianfan Xu, who has been collaborating with General Motors in the field of thermoelectric research for a decade.
The electricity generated by a TEG can be used to charge batteries and run the car's electrical systems, cutting-back the engine's workload and resulting in better fuel economy.
The initial aim is to reduce fuel consumption by five percent, with the hope that future developments which work at higher temperatures will yield more electricity and be capable of doubling the fuel savings to ten percent.
Thermoelectric generators create electricity directly from a temperature difference, though the limiting factor in car exhaust systems until now has been the extreme temperatures – from 700 to 1000 degrees Celsius. The focus will hence be to develop TEGs capable of working at such temperatures and to develop a range of specific TEGs that work at different temperatures to more efficiently extract energy at different points in the exhaust as the gases cool down during their journey.
Your article doesn\'t say what magnitude of temperature difference would be optimal, only that the very high temperatures of car exhausts have been problematic hitherto.
Could it be used to harvest energy from the heat output from air conditioners -thereby reducing overall running costs?
The first refrigeration machine by absorbing system was patented in 1859 by Ferdinand Carré.
This system uses the passage of a binary fluid (water/ammonia or water/lithium bromide) through the heating generator.
There is a great industrial use for this process, as well as home refrigerators operate by propane or kerosene heaters in areas without electricity.
However, due to those fluid toxicity, there is no way to use this system in vehicles that may be involved in accidents. The fluid tank could be broke and the result would be lethal to occupants.
The search for a nontoxic binary fluid could replace the current air conditioning system by compression by that of absorption, in all vehicles powered by internal combustion engines, generating significant cost savings, by harnessing the energy lost as heat.
Has there been a big leap in efficiency of Peltier junction technology? A Peltier junction works as both a solid state heat pump and as a heat to electricity generator, though they\'re much less efficient at converting heat to electricity.
It\'s the same technology that\'s been used in RTG, Radioisotope Thermal Generator, originally called SNAP or System for Nuclear Auxiliary Power in the 60\'s and early 70\'s, which has been used to power Soviet lighthouses, remotely located communications equipment, the Viking Mars landers, various deep space probes and rumored to be used on spy satellites.
No working fluids involved, Sergius. They are intending direct conversion as in the Peltier junction mentioned by facebook user.
A 100 hp car typically has near 100hp in exhaust gas energy, so I read. We typically harness that to pump more air into the chambers, thus boosting the volumetric efficiency and in turn , the h.p. of the motor. we do this with current materials and temperatures.
What if the energy turned a generator instead of an air pump. I bet the first gen would beat their 10% goal. But it might be too low tech to get funded.....
Please respond if you know more than I have read, and explain it? thanks in advance.
Waltinseattle, just pop a little water injector upstream of the generator and... hey presto you have a steam turbine harvesting the heat energy and the kinetic energy of the exhaust gases. Been meaning to build one of these for a while.
I totaly like Doug MacLeod\'s idea. It might be a bit spacey for a car but if you can use the 800C (or so) exhaust to create 200C steam and let a normal steampowered turbine drive a generator it is just excellent. The hot gas is already there so just add water to expand the volume even more. I suppose you dont have to use destilled water for a normal turbine and finally we might see cars that waste 30% instead of 70% of the precious fossile enery to generate useless hot air.
I\'m not dissing the thermoelectric technology, it might be promising, but steam and turbines are existing technology. Why not use it. Maybe turbines and silencers are a bad combo so if will not work in cars then maybe in stationary electric powergenerators.
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