Surface-mount adhesives used in microchannel production

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Engineers at Oregon State University (OSU) have invented a new way to use surface-mount adhesives in the production of low-temperature, microchannel heat exchangers.

This type of technology will be needed, researchers say, in applications including next-generation computers, lasers, consumer electronics, vehicle-cooling systems, fuel processors and miniature heat pumps.

‘Even though microchannel arrays have enormous potential for more efficient heat transfer and chemical reactions, high production costs have so far held back the broad, mainstream use of the technology,’ said Brian Paul, a professor in the OSU School of Mechanical, Industrial and Manufacturing Engineering.

‘In certain applications, this new approach has reduced material costs by 50 per cent,’ added Paul. ‘It could cut production bonding costs by more than 90 per cent, compared with existing approaches to microchannel lamination. And the use of surface-mount adhesives is directly translatable to the electronics assembly industry, so there is less risk going to market.’

Microchannels can be patterned into the surface of a metal or plastic, and can be designed to speed up the heat exchange between fluids, or the mixing and separation of fluids during chemical reactions. The accelerated heat and mass transfer leads to smaller heat exchangers and chemical reactors and separators.

According to OSU, cost and production issues have until now constrained the wider industrial use of this technology.

‘We have demonstrated the use of surface-mount adhesives to create microchannels on a wide variety of metals, including aluminium, which is very cheap,’ said Prawin Paulraj, an OSU doctoral candidate and lead author on the study reported in the Journal of Manufacturing Processes. ‘Bonding aluminium is difficult with conventional techniques.’

These very thin pieces of patterned metal can be bonded one on top of another to increase the number of microchannels in a heat exchanger, and the amount of fluid that can be processed. Creation of laminated microchannel arrays in a wide variety of materials is possible, including aluminium, copper, titanium, stainless steel and other metals.

‘In computers and electronics, the heat generated by the electrical circuit is a limiting factor in how small you can make it,’ said Paulraj. ‘Microchannel process technology provides an efficient way to cool computers and consumer electronics, and make them even smaller.’

The adhesives are limited in temperature to about that of boiling water. The researchers say that possible uses might include radiators to cool a vehicle engine or small heat pumps for air conditioning in buildings.

The university is now seeking a commercial partner to continue development and marketing of the technology.