Nitinol Engine

That brings back memorys, I remember many years ago, there was talk of its use in power stations, to recover the lost heat in the turbine condenser. I think a film was made of the concept, but not sure?

Since the era of Ridgeway Banks et.al. apparently some VIP's have believed SMA's deserved more than a paragraph or two on Carnot efficiency, particularly since, according to my research, "most gasoline combustion engines average around 20 percent thermal efficiency." There are also vast amounts of heat energy wasted in industrial processes.

Proceedings of the Nitinol Heat Engine Conference -- c. 1978

GM receives grant in 2011 -- during the Obama Administration

This would be a great exercise for a student to describe the theoretical and practical limitations of such a device.

...as would a comparison exercise between the Nitinol Engine and the Stirling Engine on similar heat sources and sinks. GA.

I think a more diligent exercise would be for students to elaborate upon what scientists were saying about the theoretical and practical limitations of powered flight circa the Wright brothers era.

Then again, what were the theoretical and practical limitations of manned flight in terms of scientific principles of time?

The Obama Administration gave General Motors a $3.5 million grant to study the practicality of utilizing nitinol to increase the efficiency of the gasoline engine.

What was developed as a result? Simply actuators to replace solenoids in vehicles

Looks like it's been around for a few decades now and so far nothing major.

1970 or 80's Nitinol motor video.

McDonald Douglas spent two years on it and ..... Where'd it go?

Even more intriguing....

How old was that video, again?

It would also be interesting to know the hp/weight, hp/volume, and hp/cost ratios.

I thought about how the stresses that are induced over time (Which is the drive mechanism), how this would effect the life of the drives., I came across this paper.

Reinforces what you pointed out.

Which looking at the efficiency that was presented one could extrapolate power output using known given inputs, (such as CSA of Nitinol, ΔT, etc...). Keeping in mind this is still a lab model.

a schematic displacement–temperature curve under constant tensile force for Nitinol that indicates the transformation temperatures as well as the three general regions for which fatigue data have been generated. The monotonic stress–strain curves at test temperatures: b below Mf (100% martensite), which is characterised with a low stress plateau and a large remnant strain after unloading from 6% strain; c above Af (100% austenite), which is characterised by an increased upper stress plateau (transformation from austenite to deformed martensite), an unloading plateau (transformation from martensite to austenite) and a return to the original shape; d above Md, the temperature above which plasticity is the dominant deformation accommodation mechanism. After Pelton et al.7

Using supercapacitor the record for return to martensenic for was fractions of a sec.

So, to simplify further for the sake of laymen e.g. myself:

Maximizing thermal efficiency would necessitate a wide hysteresis, i.e. difference in temps between A_{s and} M_{f ?} If so, is optimization for it's own sake necessarily pragmatic?

For example, new Ni-Ti-Cu ternary alloys have been created and are available with very narrow hysteresis ranges of +/-5C [would that be 9 degrees F?] making it possible to produce useful mechanical force from relatively small environmental temperature differences.

"hysteresis ranges of +/-5C" Sorry, that should read: "hysteresis ranges of < 5 C"

Although mathematics were once considered my forte, I got lost within the cryptology of it and the fact that I can't see the physical world in terms of numbers alone. So what is h value?

So the efficiency of an engine would depend on the temperature differential between the Martensite and Austentite phases?

(They) did something as simple as adding copper to the amalgam, and achieved transition in as little as five degrees F temperature differential as of recently. SINCE either inputting heat or mechanical energy have been the main means to produce power from now onto antiquity.... exactly WHAT would be the limitations except a failure to translate numbers into a practical model?

You gotta love the Wiki...

https://en.wikipedia.org/wiki/Nickel_titanium

http://www.google.com/patents/US4450686

I have heard of some applications a few years ago where nitinol was used in vent panel actuators in nursery greenhouses.

If you could couple this up with a free energy source, such as solar, you might be able to make something of it.

I thought I posted this yesterday, but I guess not. I'd say, that indeed it can be scaled up. How's this for scaling? Huge Nitinol Spring. It gave me the incentive to build a miiniature heat engine based on the same principle. The springs I was able to get were from Belgium about 10mm in diameter, 30mm long unstretched, and 1mm in cross section. The nitinol had an activation temp of 114F and the springs were extendable again after cooling approx. 20F.. Video posted on YouTube Dual-spring Nitinol Heat Engine. I appreciate your impressions of the above videos. I have since designed in 3-D software a prototype sketch of a solar-powered design...

Why did this thread hit a brick wall?!!!

“It’s not a cheeseburger we’re talking about... so you have to be able to focus on one thing at a time, not four things,” said Kimberly Bailey Parr.