The Minto wheel is a heat engine 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 (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 and density.
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.[1]
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 a patent granted for a design similar to the Minto wheel. The patent suggests lamps as heating sources.[2]
US Patent US242454, granted to the Iske brothers
US242454-0-colored.png
US Patent US243909, granted to the Iske brothers
Figure 1
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.[3]
US Patent US250821
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[4] similarly to Israel L. Landis design.
US Patent 253867
Figure 1
Figure 4
US Patent US253868
Figure 1
Figure 2 and 3
US Patent 271639
Figure 1
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[5] and 1946[6] by two different inventors.
drinking bird US patents
Arthur M. Hillery, 1944
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.[7] Based on the working fluid, his improved wheel is also known as "Freon Power Wheel".[8] Popular Science reported about in its March 1976 issue.[8]
Examples
A working example of a Minto wheel was first published in a series of articles in The Mother Earth News, Issues #38 March, #39 May and #40 July 1976. Test units constructed by Mother Earth News (Issue 40, July 1976) and the MythBusters (Episode 24, December 5, 2004 – "Ming Dynasty Astronaut") did work to convert temperature difference into torque; however not as well as overenthusiastic boosters claimed.
See also
Drinking bird
Stirling engine
Ocean Thermal Energy Conversion
References
Minto's pamphlet
US243909 - 1881 patent for the device
US250821
https://www.google.com/patents/US253868
https://www.google.com/patents/US2384168
https://www.google.com/patents/US2402463
http://www.keelynet.com/minto/minto2.htm
http://www.rexresearch.com/minto/minto.htm
External links
Wikimedia Commons has media related to Minto wheel.
Internet Archive archive of scans of the 1976 The Mother Earth News articles
Wally Minto's original booklet
Minto outline
YouTube video of a model Minto wheel in operation
YouTube 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
vte
Heat engines
Carnot engine Fluidyne Gas turbine Hot air Jet Minto wheel Photo-Carnot engine Piston Pistonless (Rotary) Rijke tube Rocket Split-single Steam (reciprocating) Steam turbine Stirling Thermoacoustic
Beale number West number
Timeline of heat engine technology
Thermodynamic cycle
Hellenica World - Scientific Library
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