Stirling engines in production vehicles?

[Conceptual]

http://blog.hemmings.com/index.php/2009 ... -vehicles/


Stirling engines in production vehicles?

Why was this not pushed harder?

[tomislavp4]

"Ford, GM, and American Motors Corp. spent millions of dollars developing Stirling engines for cars, back in the 1970's. Ford even built a Stirling that could drive away from the curb (with relatively low power) twenty seconds after you turned the start key! Many prototypes were built and tested. Then oil prices came down in the 1980's, and people started to buy bigger cars. Suddenly there was no compelling reason to build an engine that was substantially more efficient than internal combustion engines, but wouldn't start instantly." -from the FAQ at http://www.stirlingengine.com/

You can help efficiency by placing them in other places too... like for example the exhaust and the cooling system, you don´t have to use them as the primary engine... I certanly would like to see them around more often

[Conceptual]

I would just like to see this revisited with modern technology...

[Flummo]

The Stirling is a low power engine compared to it's size, and it reacts slowly to changes in power - stepping on the pedal and waiting 10-20 seconds before the car reacts would be bad, but even worse if the car continues on full power after you take the foot off the pedal! Sure, some problems can probably be ironed out with time and money, but I think the Stirling engine would work best for powering a generator in a hybrid car.

[Conceptual]

The Stirling is a low power engine compared to it's size, and it reacts slowly to changes in power - stepping on the pedal and waiting 10-20 seconds before the car reacts would be bad, but even worse if the car continues on full power after you take the foot off the pedal! Sure, some problems can probably be ironed out with time and money, but I think the Stirling engine would work best for powering a generator in a hybrid car.

that would be in line with "revisiting it with modern technology"...

[se7725]

I think it is very possible that the Stirling engine could make a come back. Although its not really usable as a direct power source to turn the driving wheels its attributes would lend itself to being a suitable hybrid power source. An example would be something similar the the volt or Fisker concepts that use their engines only to generate electricity. That way it could run for a long period at peek efficiency as the electricity being generated could be diverted between the motor diving the wheels and recharging the battery.

[Flummo]

The swedish Gotland class submarines actually uses stirling engines, I believe they are used to power generators but I am not sure and don't have time to look into it right now.

And by the way, the US navy borrowed one sub for navy exercises, it turnes out it is so silent not even they can detect it. I'm sure that has made a couple of americans nervous, don't you think? (Yes, I'm swedish, in case you hadn't guessed already.)

[tomislavp4]

Yeah, just find the wiki article about them, it´s all there. They are the only subs in the world (non nuclear) that can stay underwater for 2 weeks The engines they use were developed in the mid 80´s if I remember corectly....

The low power to weight ratio is the main problem, be it in hybrid or non hybrid applications. If you take the Volt for example, the stirling would be around 30% bigger than the 4 cyl it uses, offcourse it woulld weigh more too. Then you´ll need bigger heat exchanger that would increase the drag.....we´ll never know untill somebody dares to build such thing but that´s my guess

[fasterthanyou]

Sorry for bumping a 4 years old thread but after reading this report from MOD I and MOD II projects, I am wondering why no one push for the development of this kind of engine. From the reports, you can see that stirling engine is very feasible for automotive application. Low power/weight issue clearly not as big as claimed, at least not substantial enough to make this infeasible. Drivability also reported as adequate and start-up time not that bad (Max 30 sec).

http://mac6.ma.psu.edu/stirling/reports ... 021349.pdf

[bevlin761]

Sure, some problems can probably be ironed out with time and money, but I think the Stirling engine would work best for powering a generator in a hybrid car.

[Chengine]

There is new concept in improving engine efficiency by air injection into cylinder of combustion engine during exhaust cycle.
When a engine is in partial load, too much of the residual exhaust gas remains in the cylinder mixing with just very small amount of fresh air. During combustion, the low temperature H2O and CO2 from waste gas just suck the energy off the combustion, lower overall temperature, thus lower the mean pressure.

I expect an engine with air injection to purge out residual waste gas to improve gas economy, especially in city traffic by 30%.

Also the air injection will reduce pollution of CO and HC, even without catalytic converter, as the oxidation process in exhaust cycle should be very efficient.

In fact, This new engine performs half way between Otto and Diesel engine.

Chengine

[tok-tokkie]

Those are a whole lot of statements. Give us a link to academic research that justifies them.

[Chengine]

The academic source is "Internal Combustion engine fundamentals" by John Heywood. On page 617, there is a graph on Effect of gas temperature on HC and CO burn up in the exhaust, SI engine at 1600 rpm. This covers my claim of pollution elimination for Otto engines

Yes, I made a lot of claims. They are too numerous to list. As I can only supply so much info in one posting.

If you are interested, first item is the patent US#8434462. I also have a power point presentation. I was very surprised that this engine concept was not thought of before.

Chengine

[Chengine]

Another source of residual gas effect on combustion efficiency is also in the same Heywood book.
On page 405, Fig. 9-26, Effect of burned gas mole fraction in unburned mixture on Laminar burning velocity.
From the graph, it can be seen that combustion velocity dropped from normalized one to 0.2 when mole Fraction is
from 0 to 0.3.

The impact of waste gas on combustion efficiency is well known. One of the reason high power sports cars are gas guzzler no matter how light the car is, is because the cars are used in very light load condition. and too much residual waste gas mixed with just small amount of fresh air destroy efficiency.

With exhaust gas completely purged with injected air, we can have maximum torque at low rpm as well.

The peak torque correspond to perfect scavenging of waste gas from the cylinder.

Cheers

Chengine

[PhillipM]

If you're surprised your engine concept was never thought of before, the answer is, it probably was, and either didn't work or had too many downsides....