Fredrik Ljungström (16 June 1875 in Stockholm – 18 February 1964 in Stockholm) was a Swedish engineer, technical designer and an industrialist. Together with his older brother Birger Ljungström (1872–1948) he invented high-pressure steam boilers.
They also worked out a new type steam turbine, the Ljungström radial turbine, patened by his brother Birger Ljungström in 1894. The turbine principle was the base for the company ALÅ (Ljungström steam turbine Co.) founded in 1908 that owned all the patents. In 1913 they founded the separate company STAL (Swedish turbine manufacturing Co.), and moved the small workshop from Stockholm to Finspång. This company handled the manufacturing and sales of complete steam turbine driven electric generators. STAL was acquired in 1916 by ASEA as they wished to market complete packages with turbine driven electric generators. The brothers then left the company but kept control over the all the patents and manufacturing licenses for the Ljungström steam turbines within the company ALÅ.
They also designed a number of steam turbine locomotives, some of which were highly successful. The first attempt in 1921 was a rather odd-looking machine. Its three driving axles were located under the tender, and the cab and boiler sat on unpowered wheels. Later they changed this design with driving wheels on both the boiler carriage and the tender with separate turbines. The second design was a 2-8-0 similar to a successful freight design. Built in 1930 and 1936 by Nydqvist & Holm, these locomotives replaced conventional ones on the Grängesberg-Oxelösund Railway. No condenser was fitted, as its complexity outweighed its thermodynamic advantages. The wheels were driven by a jackshaft. These engines were not retired until the 1950s when the line was electrified. He also invented an efficient air preheater, which even in a modern utility boiler provides up to 20 percent of the total heat transfer in the boiler process, but only represents 2 percent of the investment.
Fredrik Ljungström also invented a technology for oil shale underground gasification by electrical energy (Ljungström method) and made several inventions related to sailing boats. He also worked with new ideas for sailing boats. The Ljungstrom sailboat with the circular arc hull and the Ljungstrom rig, without a boom and double sail that can work as a spinnaker, is named after Fredrik Ljungström.
Ljungström steam turbine locomotive prototype workshop at Gåshaga, Lidingö outside Stockholm, built in 1918. Here they also worked out the Ljungström heat exchanger for their locomotives.
Ljungström sailboat, 1950. USPTO No. 2107303, Februari 8, 1938.
Main patent drawings for Ljungström heat exchanger, USPTO No. 1746598, 1930.
- In 1948 he was awarded KTH Prize (Swedish Royal Institute of Technology).
- In 1949 he was awarded James Watt International Gold Medal of the Institution of Mechanical Engineers.
- "The Ljungström Air Preheater 1920. An International Historic Mechanical Engineering Landmark" (PDF). Svenska Mekanisters Riksförening; American Society of Mechanical Engineers. Retrieved 2009-01-10.
- Samtliga pristagare kth.se, retrieved on 2009-02-05
- James Watt International Medal Recipients imeche.org, retrieved on 2009-02-05
- SRM 100 year jubilee, the story about the Ljungström brothers.
- Free Patents Online, Fredrik Ljungstrom.
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