Laser welding used to optimise tube finning for industry
Researchers at Russia’s Ural Federal University have optimised tube finning technology using laser welding.
The technology offers increased heat exchange, decreased material usage and reduced cost compared to other designs.
Ribbed tubes are used in the chemical, petrochemical, and refining industry (condensers, gas heaters, gas coolers), in machine-building (compressor and refrigerating units, oil coolers), in the nuclear industry (for the production of coolers, dryers, and steam heaters), and in air conditioning and heating systems.
For their take on the technology, the engineers have laser welded the ribs with a continuous seam so that the metal of the pipe and the rib become homogeneous and inseparable.
‘The speed of laser welding is very high – up to 9m per minute – so the heat input into the metal is small,’ explained chief designer of the project, Vladimir Podgorbunskikh. ‘This means that metal is heated with high power, but at a very high speed, and during the passage of the beam it has time to melt, flow to the pipe and tack, while the pipe has no time to heat up and deform, which cannot be achieved by condenser welding.’
The laser enables formation of a homogeneous crystal lattice in the welding area of the tube and fin. This makes it possible to obtain more efficient heat-exchange characteristics with less metal consumption, as well as increased strength characteristics compared to world analogues.
‘We are the first in Russia to take up this work and perform it,’ said Podgorbunskikh. ‘At the same time, our products are 1.5 times cheaper than their foreign analogues, but with better welding quality and 15 per cent higher heat emission efficiency.’
The Experimental-Production Complex (EPC) of Ural Federal University has already produced a batch of pipes for its first commercial order, which are now being tested in production. A second order has since been placed for finned tubes with a smaller diameter.
The first order was fulfilled in three months: 9,200 fins were welded on 20 pipes (460 for each pipe).
‘We worked off this order in “manual mode”', said Podgorbunskikh. ‘Now we have signed a contract for an automated laser welding system. In December we will get the equipment, adjust it, work out the technology, and in spring 2022 we will be able to launch serial production. This will increase the speed of work up to three to five times. And, if there are large orders, the robot could potentially work around the clock, which also increases productivity.’