POSCO May Expedite Seoul to Busan Hyperloop
POSCO HyperloopPOSCO

POSCO May Expedite Seoul to Busan Hyperloop

The maximum speed of hyperloop is about 1,200 kilometer per hour, comparable to the speed of sound and faster than the Boeing 787. The travel

The maximum speed of hyperloop is about 1,200 kilometer per hour, comparable to the speed of sound and faster than the Boeing 787. The travel time from Seoul to Busan may take merely 20 minutes. It means that commuting from Busan to Seoul can become possible. When the Korean Train Express was first introduced in 2004, it became possible to travel Seoul-Busan back and forth within a day. With the hyperloop, this would be shortened to within an hour.

The concept of hyperloop became widely known to the public when Elon Musk, CEO of Tesla and SpaceX, mentioned it. When he first unveiled the concept of Hyperloop in 2013, demonstrating a high-speed train in the form of a capsule moving inside a vacuum tube, some critics were skeptical, dismissing Musk’s idea as being science fiction. However, research on this idea began as it received spotlight from the media, and last month, a US company, Virgin Hyperloop One, succeeded in the first manned test run in an experimental tunnel in the Nevada desert near Las Vegas. Since it was still in the test phase, the tunnel was just 500 meter long and the speed was only 172 kilometer per hour, which is 1/7 of the speed of sound. However, it was enough to prove that the concept of traveling within a vacuum tube wasn’t science fiction anymore.

However, in order for Hyperloop to be commercialized, there are still some issues to be resolved. Imagine a train running at a speed of 1,200 kilometers per hour within a tube of tens or hundreds of kilometers in a vacuum state.

The first issue is securing airtightness and safety. Since the long tube has to be kept in a vacuum state, ensuring airtightness is a must, as well as the safety of the train which is running at super high speed. The tubes that make up the track of the hyperloop must not only be able to withstand the load of the tube itself but also the load of the pod, the shock, and thermal expansion caused by high-speed driving. Another factor the tube must withstand is air pressure, which is difficult for objects within a vacuum state. If the tube deforms or cracks due to these factors, it could lead to big accidents. This is why the material and structural technology used to fabricate the tube is crucial.

The second issue is overcoming the Kantrowitz limit. The inside of the tube is supposed to be in a vacuum state, but little amounts of air remain inside the tube. When the space between the train and the tube narrows and the speed of the train approaches the speed of sound, the air flow in the tube is blocked at some point. This is called Kantrovitz limit in technical terms. How could this be overcome? Sufficient space must be secured between the train and the tube so that the air flow within the tube is not blocked, and this entails increasing the size of the tube to find the optimum diameter.

The third issue is ensuring economic feasibility. Concrete, carbon fiber, and steel have been reviewed as tube materials. Concrete is economical but lacks airtightness, while carbon fiber is costly and lacks machinability. Accordingly, steel, which is of reasonable cost and features excellent airtightness and workability traits, has been evaluated as the most appropriate material for the tube.

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