Memory is crucial to our every day lives. Whether you're cramming for a final, stopping at the ATM, or frantically trying to locate your car keys, life would obviously be impossible without memory. Considering our primarily human concept of memory, it may come as a surprise that a specially manufactured nickel titanium alloy not only has memory, but may hold the key to producing abundant green energy.Shape memory alloy and the forgotten Nitinol motor - Wheeling renewable energy | Examiner.com
Nitinol is an alloy composed of nickel and titanium in a roughly equal atomic ratio, and is know for its shape memory and super-elastic properties. Discovered in 1958 by the Naval Ordnance Laboratory, Nitinol can be trained to "remember" a shape by heat treatment under specific circumstances. It can be bent, twisted, and pulled to any deformation, and it will return to its original shape when heated to its transformation temperature.
With careful manufacturing, the transformation temperature can be just a few degrees above room temperature, in fact, there are samples of Nitinol that transform when exposed only to the body heat available from being held in a human hand. It is 10-30 times more elastic than other metals, especially when approaching the transformation threshold, which means deforming Nitinol requires very little effort. Nitinol is capable of storing more energy for a given mass than any other known substance.
Where have you been all my life?
Despite its obvious potential applications, the cost and difficulties involved in manufacturing this alloy, prevented commercial use of Nitinol until the 1990's. Several industries, including medical, engineering, architectural, mechanical and more, have taken advantage of the unique shape-memory properties, however, the most revolutionary use of Nitinol may be the invention of the nickel-titanium heat engine patented by Ridgway Banks in 1984.
The memory motor.
Banks, a researcher at the Lawrence Berkeley Laboratory, developed a fuel-less motor capable of using hot and cold water and the force of shape transformation to spin a partially submerged wheel equipped with Nitinol paddles. Several working models can be found throughout the internet and many solar powered models have been proven to generate useful amounts of electricity. Incredibly, this idea has received little media attention and science, unlike Nitinol, has long since forgotten.
Nitinol engines are essentially super efficient, metallic, one piece Stirling engines, and paired with a Fresnel lens to heat a water reservoir, a nickel-titanium motor could run for days, weeks, or years without maintenance; Because water can be obtained for free with a solar condenser hydro electric generator, abundant free electricity can be produced with absolutely no environmental impacts, no safety concerns, and no cost. When will the scientific community acknowledge that the benefits of combining several currently understood technologies into one whole system often grant us capabilities and efficiency greater than the sum of the individual parts.
This is an attempt to get away from expensive and dangerous gases. It operates somewhat the same as a regular Minto wheel but instead of using a low boiling point liquid to provide the pumping action it uses a set of nitinol springs.Solar Hot Water Nitinol Heat Engines
Nitinol or better known as memory metal can be bent and when heated to a certain temperature will return to it's normal shape with quite a bit of force. This fact has been used to make all kinds of regulating devices but here I am using it formed in a set of springs.
What happens is the NiTi springs are submerged in hot water (varies depending on spring composition) and they contract. They pull 2 cables. One goes through a pully 90 degrees and then pulls shut the lower bellows full of water. The water is pumped to the opposite bellows and gravity does it's thing as normal
The other cable just goes to another spring farther up on the arm and stretches when the other contracts. This spring is alot lighter than the operating spring and only serves to help stretch the operating spring back out when it cools out of the water. This allows the bellows to open back up a little easier when it is it's time to be filled and helps keep the operating spring working properly.
I found the springs here at http://www.robotstore.com They come 4 to a pack and at the time this is being written costs $41.95 . That would put the cost of each 10' wheel at about $1000 to build from new materials I did some math calculations on what the output would be for a 10 wheel on one shaft version. At 10 rpm the output would be over .24 hp. Thats 178 watts or 14.8 amps at 12 volts! The output rpm can be geared up to operate a generator for battery charging. This design is actually capable of even faster rotation but that would stress the springs and reduce the their usable lifetime. If not stressed the springs will operate for millions of operations meaning many years..
Nitinol springs can be heated by electricty also but they pull a lot of current. I do not suggest the use of solar heat as they can be easily damaged if heated too hot and direct solar heat would be extremely difficult to regulate to prevent overheating. Solar energy used to heat water works alot better especially since this setup doesn't need a very big tank at all.
The second picture is a teeter-totter type setup operating two simple pumps. One pump would be used to pump water through a solar panel to heat the two tanks and the other would be used for pumping water to whatever you might want. I was thinking of using the second pump to pump water to the top of a 10' water wheel. It wouldn't be really fast but if the system could pump 10 times a minute, that would give me 2-3 rpm on the wheel hopefully. This setup could be multiplied side by side as one small solar panel could easily provide the heat for a number of teeter-totters .
by Jillcha Wakjira - Abstract: The invention of shape memory alloys spurred a period of intense interest in the area of heat engines in the late 70's and early 80's. It was believed that these engines could use heat from low temperature sources such as solar heated water, geothermal hot water and rejected heat from conventional engines as a significant source of power. The interest has since dwindled, largely because small prototype devices developed in the laboratory could not be scaled up to produce significant power. It is believed that the scaled-up designs failed because they were dependent on friction as the driving mechanism, which led to large energy losses and slip. This thesis proposes a new chain and sprocket driving mechanism that is independent of friction and should therefore allow for large-scale power generation.http://scholar.lib.vt.edu/theses/available/etd-02102001-172947/unrestricted/ETD.pdf
This thesis begins by presenting properties and applications of shape memory alloys. The proposed design is then described in detail, followed by a review of the evolution that led to the final design. A brief chapter on thermodynamic modeling and a summary chapter suggesting improvements on the current design follow.