3D printed heat exchanger is estimated to be 50% more efficient

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A new type of lightweight 3D-printed heat exchanger with a repeating maze-like gyroid architecture design is more compact and efficient than its conventional counterparts, according to its developers. A team led by engineers from the University of Glasgow developed the system, which exploits the unique properties of microscopic surfaces to create a high performance heat exchanger.

Heat exchangers, devices that transfer heat between fluids without mixing them, have a wide range of practical applications. Heat exchangers that transfer thermal energy between fluids are used in systems such as refrigeration, fuel cells, and the types of internal combustion engines used in cars and airplanes.

In a new paper published in Applied Thermal Engineering, the researchers describe how they developed and built the prototype system, which they estimate to be 50% more efficient than a market-leading conventional heat exchanger despite being one-tenth the size.

The system owes its effectiveness to the design of structured surfaces on which the liquids circulate through the exchanger. The cube-shaped exchanger draws water through a core, dotted with tiny holes arranged in a gyroid configuration.

Design and fabrication of compact gyroid lattice heat exchanger (a) CAD surface model of 4.6mm x 4.6mm x 4.6mm gyroid unit cell (b) CAD model of exchanger core gyroid lattice comprising a lattice of 7 x 7 x 7 gyroid unit cells with a wall thickness of 300 µm and a porosity of 80% (c) CAD cross-sectional view of the heat exchanger clearly showing the gyroid core, plates cover and header assembly (d) 3D printed heat exchanger (e) Micro-computed X-ray tomographic image of a plane passing through the mid-height of the heat exchanger and (f) heat exchanger heat 3D printed without cover plate (g) small scale imperfections.

Gyroids are one of a group of cellular designs that are constructed using triply periodic minimal surface geometries, having non-self-intersecting and highly symmetrical periodic surfaces.

The team chose to use a repetitive gyroid architecture for its heat exchanger because the efficiency of heat exchange is related to its surface area – the larger the surface area, the more opportunity the fluids have to transmit their heat energy. from one to the other. This means that objects with large surface areas can cool or heat fluids faster than those with more limited surface areas.

The team’s micro-scale gyroid design, which they fabricated from a simple photopolymer using a sophisticated 3D printer, designs a large surface area into a compact cube measuring 32.2mm each side and weighing only eight grams.

By drawing water from this dense labyrinth, the researchers were able to show temperature variations of between 10 and 20 ºC when the water passed through their heat exchanger at a speed of between 100 and 270 millimeters per minute.

The team measured the heat transfer coefficient of their new exchanger – the measure of its efficiency in transferring heat between the fluid and its surfaces – to determine its performance against a series of conventional heat exchangers of sizes different made from materials such as polymers and metals.

They found that the efficiency of their new heat exchanger was 50% higher than that of a thermodynamically equivalent and most efficient counterflow heat exchanger, even though their newly developed prototype was only making 10% of its cut.

The 3D printed heat exchanger is estimated to be 50% more efficient.  Created using a repeating gyroid architecture design.
Simulated thermal iso-surface for (a) hot fluid (b) cold fluid (c) partition wall and (d) pressure contours corresponding to experimental test number 1

The research was led by Dr Shanmugam Kumar from the University of Glasgow’s James Watt School of Engineering, alongside colleagues from Swansea University and Khalifa University of Science and Technology in Abu Dhabi.

Dr Kumar said: “We have been working for several years to find new applications for this type of 3D printed and micro-architectural lattice. We have already demonstrated how they can be used for purposes such as recyclable high-performance batteries and the development of future “smart” medical devices such as back prostheses and orthoses.

“This latest paper shows that we can use these gyroid network architectures to create a material with a remarkably large surface-to-volume ratio that lends itself very well to heat exchange.”

“Being able to develop smaller, lighter and more efficient heat exchangers could help us develop refrigeration systems that require less energy, for example, or more efficient motors that can be cooled more efficiently. We want to further develop this technology with future research.

The team’s paper, titled “High performance, micro-architected, compact heat exchanger enabled by 3D printing”, is published in Applied Thermal Engineering. The research was supported by funding from the Abu Dhabi National Oil Company.

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