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GM Seeks Patents To Harvest Vehicle Engine Heat

4284 Views 7 Replies 5 Participants Last post by  bonaire
GM is hoping to increase the efficiency of their combustion engine cars by recapturing some of the emitted heat. The post below shows how they are thinking of doing this. Short answer: shape memory materials that change shape at different temperatures.
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Shape memory isn't new. Most thermostats have this feature. Maybe they have found a new use for shape memory by converting waste heat into a form of mechanical energy, which can be used in other forms.

Yes, they are taking advantage of the different shapes of the shape memory material as it changes between its austenite and martensite phases at different temperatures and converting that mechanical energy into electricity via a generator.
>> According to GM, this technique can currently improve fuel efficiency by 3 percent

Ah, yes. But so could some of these:
- proper tire inflation and then 2-3 psi harder than recommended.
- driving 5mph slower on the highway.
- better aerodynamics rather than "sharp designs"

3% is very very little. 22 mpg with 3% improvement is 22.66 mpg. It will affect the MSRP by adding in the costs of this additional engineering. For the consumer, the added cost will not be realized as return on investment.

ICE engines are just inefficient. And people want "high horsepower" vehicles. We should hire psychologists to talk people down from their wants and establish some reasonable, responsible thinking patterns.
I agree that 3% is just silly to move forward with these devices. GM's goal is 10%, but even then, it's a close call. Not to mention the longevity issues with a device like this. You are deforming a piece of alloy potentially millions of times. How will they avoid metal fatigue?
On the other hand, 3% of all of the fuel burned in cars in the US is a massive figure. As the great chassis engineer Steve Smith famously said, when you get down close to the minimum weight you end up taking it out one ounce at a time. We use aluminum lug nuts on our race cars, LOL.
eAssist increases MPG by 20%. That's a big number for a relatively small increase in cost. Plus it scales.
The new technology of heat regen at 3% or so is never going to go into the national fleet, due to patents, at much of a scale. The eAssist can become a new norm-of-car-manufacturer just like differentials and windshield wipers. An eAssist vehicle's technology is simple and utilizes already-viable technology techniques. Hybridization of cars does add to costs but then they reduce again due to cost-of-scale when you produce 10 Million vehicles a year can add up quickly. eAssist and similar technology could help the national vehicle mpg averages grow by 3-5 by 2020 (SUV and CUV adoption should be included).
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