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Johannes Juul. Photo: Energy Museum
Johannes Juul (1887 - 1969).
Johannes Juul was a Danish engineer who is remembered for the important part he played in the development of wind turbines. His achievements are included in the Danish Culture Canon.
Source:
en.wikipedia.org
It was Johannes Juul, a former student of Paul la Cour, who introduced several innovations in his wind turbine designs that became the reason for the success of Danish concept wind turbines. He introduced the concept of stall regulated wind turbine blades that operates on constant speed and controls the rotor power at high wind speeds along with pitchable blades tips to control the rotor speed during gusts and storms.
Source:
windmillstech.com
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Photo: Energy Museum
1904. As a 17-year-old, Johannes Juul took part in Paul la Cour's first "wind electrician course" at Askov College. In the photo, Juul is seen as No. 3 from the right in the back row. Paul la Cour No. 1 from the left in the middle row.
1914. Authorized electrical installer.
1915. Juul completed the then brand new "High voltage test" at Helsingor Technical School. With this, he could carry out work with high voltage cables.
1915 - 1926. Independent installation business in Koge. Through his company, Juul invented and improved his electrical overhead line equipment. In his factory, high-voltage equipment was produced, part of which was purchased by the electricity company SEAS. His new support insulators were easier to replace and more secure.
1925. Juul obtained patent no. 34383 on "Device for thermal switches."
Source: "Johannes Juul and his mills", Jytte Thorndahl, Museum Inspector.
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Photo: Energy Museum
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1926. Employed by SEAS (now Andel), in Haslev, as an installation foreman with responsibility for the company's wiring - with the condition that Juul could conduct independent research within the framework SEAS could offer him.
1934. Juul patented the invention of a low-voltage stove that was sold and used until the late 50s. Photo, above, shows a low-voltage stove in Juul's kitchen.
1940. The invention meant his admission to the Engineers Association.
12 Septenber 2023. Andel Elmuseum in Haslev has donated one of Juul's low-voltage stoves to "Juuls Museum" in Gedser. (See Photo below)
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More info and photos. Including a high-voltage baking oven, donated by a member of our Association.
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Photo: Energy Museum
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1948. Photo, above, shows Juul's wind tunnel at SEAS in Haslev. Here he tested at least 25 rotor blade profiles.
1949. Juul arrived at his ideal blade shape, which he finally used on three test turbines: the Vester Egesborg Turbine, the Bogø Turbine and the Gedser Wind Turbine.
Source: "Kapitler af vindkraftens historie i Danmark. 6. voll." Jytte Thorndahl, Museuminspector, Energy Museum.
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Photo: Energy Museum
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1950 - Vester Egesborg - downwind, 10 kW/ upwind, 15 kW
Rated power: 10.0 kW. Tower/Hub height: 12.0 m. - Type: Lattice. Rotor diameter: 8.0 m. - Swept area: 50,0 m² - Number of blades: 4. - Power density 1: 200,0 W/m² - 2: 5.0 m²/kW.
Source: en.wind-turbine-models.com<
The Vester Egesborg test-turbine started out with 2 blades. These were replaced as they could not withstand a wind force of 25 m/s. The 2 new blades were stabilized with a stays system, so that the pressure on the blades was absorbed by the stays attached to the middle of the blades. After further breakage, a third set of blades was installed, where the two main blades were braced in a stays system with two small support blades. This made the rotor system more stable, and Juul concluded that it was more appropriate to build turbines with at least 3 blades. The original 2 generators (10 kW and 3 kW) were replaced with a single 15 kW. Furthermore, Juul switched from downwind to upwind after mounting the second set of blades.
Note (in photo) the pitchable brake flaps in the blade tips - patented by Johannes Juul.
Source:
dgs.de
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Photo: Energy Museum
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1952 - Bogø - Upwind, 45 kW (Juul's second test wind turbine)
On his previous test wind turbine "the Vestenborg wind turbine", Juul had used his braking system with rotating brake flaps on the blade tips. in 1952, Juul patented this invention, a control system to protect against excessive speeds (No. 74199).
When SEAS took over a two-blade FLS acromotor direct current wind turbine on the island of Bogø in 1951, Juul had the opportunity to develop a three-blade, stall-controlled wind turbine with an asynchronous generator (45 kW) based on the same principles and with the same blade profile and airbrakes as the Vesterborg turbine.
The wind turbine on Bogø proved to be even more efficient than expected, being able to generate 65 kW - and not just the calculated 45 kW.
The Bogø wind turbine ran smoothly until 1962. Unlike the island's former DC turbine, which was often shut down at night because the island's power plant was underutilized, Juul's wind turbine was able to feed excess electricity into the SEAS power grid via a cable.
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Photo: Energy Museum
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Juul's third test turbine: The Gedser wind turbine was built with the help of the Marshall Plan in 1957.
1954. The sketch (above) shows Juul's design for a multi-rotor system. The cost price per kWh produced would be lowest with three rotors on the same tower. Juul's second sketch shows the Gedser wind turbine on a lattice tower, which was eventually replaced with a concrete tower. The result was later called "The Danish Concept".
Next in the website menu bar:
The Danish Concept
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