Fractal heat exchange
Designing optimal self-similar structures for compact counter-current heat exchange to reduce heating costs and greenhouse emissions.
The design of efficient exchange devices is an important problem in biology and engineering. In nature, lungs, leaf venation and blood circulation networks have evolved to meet multiple physiological needs. In industrial settings a variety of heat exchangers are employed, such as plate, coil and counter-current devices. A distinctive feature of the biological examples is their fractal structure, with branching and usually anastomosing geometries. The fractal design provides a large surface for exchange but occupies a compact volume.
In this project we design optimal heat exchangers for man-made use that incorporate the design efficiencies of their biological counterparts. We develop a theory that links efficiency to the geometry of the exchange surface and supply network. By crumpling the exchange area into a fractal surface, our designs can be optimized for volume as well as performance. They are especially suited to being made by 3D printing because they are not load bearing.
Optimal heat exchangers increase the efficiency of industrial processes and reduce the cost and size of passive heat exchangers in houses. The underlying theory also provides insights into respiration, which may help develop diagnostic tests for breathing disorders.
Compact heat exchangers can be designed to run at low power if the exchange is concentrated in a crumpled surface fed by a fractal network.