TWI Develops Low-Density Alloy Heat Exchanger for Enhanced Efficiency in Transport Sectors

TWI Ltd. has successfully completed a program aimed at developing diffusion bonding parameters for aluminium alloys, a critical advancement for the transport sector's move towards Net Zero emissions. Aluminium alloys, known for their lightweight properties, pose challenges in joining processes due to rapid oxide formation. TWI's breakthrough addresses these challenges, paving the way for the creation of more efficient, lightweight, and compact heat exchangers.

The transport sector's drive towards higher efficiency and reduced environmental impact has highlighted the need for advanced printed circuit heat exchanger (PCHE) technology. By utilizing photochemical etching to manufacture lightweight shims with intricate channel geometries, TWI has enhanced convective heat transfer intensity and increased the heat transfer area density. This innovation significantly reduces the footprint of heat exchanger units.

A notable example is a photochemically etched aluminium-alloy shim, featuring zig-zag microchannels (semicircular in shape with a diameter of 500 microns per channel) and integrated headers. The design operates on a cross-flow principle, with alternating shim layers for hot and cold fluids, resulting in a highly efficient heat exchanger core consisting of 60 shims (30 'hot' and 30 'cold').

By refining the diffusion bonding parameters for aluminium alloys, TWI has successfully sealed these complex features during the joining process with minimal distortion to the intricate network of channels. The demonstrator PCHE, now fully manufactured, showcases this innovative approach.

In addition to aluminium alloys, TWI explored diffusion bonding for other low-density alloys such as commercially pure titanium (Ti) and Ti6Al4V. The developed bonding parameters are ready for application in real-world components, including PCHEs.

"This development demonstrates the feasibility of using low-density alloys in PCHE applications, which is crucial for achieving industrial efficiency and environmental targets," said a TWI spokesperson. "Our work exemplifies how cutting-edge research can meet the stringent demands of modern transport sectors."