Minto Wheel
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The Minto wheel is a
heat engine A heat engine is a system that transfers thermal energy to do mechanical or electrical work. While originally conceived in the context of mechanical energy, the concept of the heat engine has been applied to various other kinds of energy, pa ...
named after Wally Minto. The engine consists of a set of sealed chambers arranged in a circle, with each chamber connected to the chamber opposite it. One chamber in each connected pair is filled with a liquid with a low boiling point (
propane Propane () is a three-carbon chain alkane with the molecular formula . It is a gas at standard temperature and pressure, but becomes liquid when compressed for transportation and storage. A by-product of natural gas processing and petroleum ref ...
(''TB'' = −42 °C) and R-12 (''TB'' = −29.8 °C) are listed in the Mother Earth News articles). Ideally, the working fluid also has a high
vapor pressure Vapor pressure or equilibrium vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indicat ...
and density.


Operation

As the lower chamber in each pair is heated, the liquid begins to vaporize, forcing the remaining liquid to travel to the upper chamber. This fluid transfer causes a weight imbalance, which causes the wheel to rotate. Minto's pamphlet also suggests obtaining a pressure differential with a dissolved gas instead of a boiling gas. Soda water or propane dissolved in kerosene are suggested.


Characteristics

The Minto wheel operates on a small temperature gradient, and produces a large amount of torque, but at very low rotational speed. The speed of rotation is directly proportional to the surface area of the containers used, the volume, and the height of the wheel. The higher the ratio of surface area to volume, the greater the rate of revolution.


History


Iske brothers and Israel L. Landis

In 1881, the Iske brothers got two patents granted for a design similar to the Minto wheel. According to the patent, the working fluid is alcohol "or other volatile liquid". Air in the tubes is to be removed and the tubes are sealed (creating a partial vacuum). The patent suggests lamps as heating sources.US243909 - 1881 patent for the device
/ref> The first patent describes glass for the bulbs and tubes. The second patent does not specify materials, but the construction implies metal. A later patent then clearly specify metal. File:US242454-0-colored.png File:US243909-Figure 1.png, Figure 1 File:US243909-Figure 3.png, Figure 3 Later the same year, Israel L. Landis got a patent for a similar engine. Different to the Minto wheel and the Iske brothers' patent, the engine was oscillating, not revolving.US250821
/ref> Landis suggested alcohol or ether as the volatile liquid. Landis suggested heating up the apparatus before removing the air from the bulb/chambers. File:US250821-Figure 1.png, Figure 1 In the following years, the Iske brothers were granted various patents, including some relating to modification and/or improvements on engines similarly to the Minto Wheel and an oscillating engine similarly to Israel L. Landis design. File:US253867-Figure 1.png, Figure 1 - motor which rotates File:US253867-Figure 4.png, Figure 4 - motor which oscillates File:US253868-Figure 1.png, Figure 1 File:US253868-Figure 2 and 3.png, Figure 2 and 3 File:US271639-0-colored.png, Figure 1 File:US271639-1-colored.png, Figure 2 and 3


Drinking bird

The oscillating types by the Iske Brothers and Landis are related to the drinking bird toy. The drinking bird is dating back to 1910s~1930s. The drinking bird was patented in the US in 1945 and 1946 by two different inventors. File:US2384168-0.png, Arthur M. Hillery, 1944 File:US2402463-0.png, Miles V. Sullivan, 1945


Wally Minto's contribution

Wally Minto experimented with different working fluids. With the working fluids he used, he got the required temperature difference down, enabling the engine - for example - to run on solar power. Based on the working fluid, his improved wheel is also known as "
Freon Freon ( ) is a registered trademark of the Chemours Company and generic descriptor for a number of halocarbon products. They are stable, nonflammable, low toxicity gases or liquids which have generally been used as refrigerants and as aerosol p ...
Power Wheel". Popular Science reported about in its March 1976 issue.


Examples

A working example of a Minto wheel was first published in a series of articles in The ''
Mother Earth News ''Mother Earth News'' is a bi-monthly American magazine that has a circulation of 500,520 . It is published in Topeka, Kansas. Since its founding, ''Mother Earth News'' has promoted renewable energy, recycling, family farms, good agricultura ...
'', Issues #38 March, #39 May and #40 July 1976. Test units constructed by ''Mother Earth News'' (Issue 40, July 1976) and the
MythBusters ''MythBusters'' is a science entertainment television series created by Peter Rees (producer), Peter Rees and produced by Beyond International in Australia. The series premiered on the Discovery Channel on January 23, 2003. It was broadcast in ...
(Episode 24, December 5, 2004 – "Ming Dynasty Astronaut") did convert temperature difference into torque, but not as well as overenthusiastic boosters claimed.


See also

* Drinking bird *
Stirling engine A Stirling engine is a heat engine that is operated by the cyclic expansion and contraction of air or other gas (the ''working fluid'') by exposing it to different temperatures, resulting in a net conversion of heat energy to mechanical Work (ph ...
*
Ocean Thermal Energy Conversion Ocean thermal energy conversion (OTEC) is a renewable energy technology that harnesses the thermocline, temperature difference between the photic zone, warm surface waters of the ocean and the deep sea, cold depths to run a heat engine to produce ...


References


External links


Internet Archive archive of scans of the 1976 The Mother Earth News articlesYouTube video of a model Minto wheel in operationYouTube video of a model Minto wheel in operation (shows smoother action from more chambers)
* patents granted to the Iske brothers
US243909 - 1881 patent for the device

US253867

US253868

US256482 - 1882 patent for the device

US271639

US673022
* patent granted to Israel L. Landis *
US250821
* http://www.genuineideas.com/HallofInventions/SolarPivots/thermoscopicSolarWheel.html {{Machine configurations, state=uncollapsed Engines External combustion engines