IN BRIEF
A magnetic coating for low-resistance pipelines
A lot of energy may be saved by helping fluids to flow more smoothly through pipelines using magnetic coatings
Thanks to optimised ferrofluids and magnets, fluids are able to flow swiftly through pipes. | Image: Laura Maria Stancanelli; Eleonora Secchi; Markus Holzne
Pipelines are everywhere. Without them, we would have neither running water nor petrol – nor, on a smaller scale, would we have life-saving infusions in hospitals. But whenever a liquid is pumped through a pipe, friction and turbulence occur. “The result is a loss of energy”, says Laura Stancanelli from the Delft University of Technology (TU Delft). Together with researchers from the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) and ETH Zurich, she has been developing a new method for reducing losses and increasing efficiency.
To do this, she and her team coated the inside of a water pipe two centimetres in diameter with a thin layer of a so-called ‘ferrofluid’ – a liquid that contains magnetic particles. Magnets placed either on the outside or directly in the pipe then ensure that the ferrofluid stays in place and isn’t washed away. “The materials used for this are quite inexpensive, so the application can easily be scaled up and down”, says Stancanelli. “The tricky part is ensuring a uniform surface coating”. To achieve this, her team experimented with different ferrofluids and magnetic strengths, optimising them depending on the flow speed and the viscosity of the liquid they wanted to transport.
This enabled them to reduce friction loss by up to 90 percent. “Even we were surprised by this result”, says Stancanelli. “A reduction of only 40 percent would already have been a success”. The advantages of this technology are multifarious, as it functions at both high and low flow rates. “The ferrofluid sort of goes with the flow”. The fluid thus never actually comes into contact with the pipe itself, meaning almost no friction.
Stancanelli believes that the technology will have different possible applications. Pipes could be coated to save energy; and it could even be used in human medicine. “Most loss-reduction techniques cannot be used in the human body”, she says. But ferrofluids could change that – for example, they could prevent blood particles from becoming damaged on the walls of stent prostheses, or stop bacteria from sticking to catheters.
