The hypothetical dishwasher which runs on superheated steam

Do you think your dishwasher isn’t doing its job properly? Some scientists believe that superheated steam is a smarter option.

While a superheated steam dishwasher sounds like the second scariest thing in your kitchen (after, of course, the pressure cooker), new research suggests that it would also be more energy and water efficient, and less polluting.

The research, published in Physics of Fluids, uses simulations to show such a dishwasher would also kill 99% of bacteria on a plate in under 25 seconds.

The virtual dishwasher is a box with an opening in the top, and a nozzle at the bottom. Dishes would be placed directly over the nozzle.

“Steam comes out of the nozzle at a very high velocity. We can see shocks, and the turbulent flow that is created has eddies and vortices,” says co-author Professor Natalie Germann, a researcher at the Technical University of Dortmund in Germany.

The simulations allowed the researchers to examine the effect of the steam on bacteria, without the associated risks – yet.

Read more: Oreology: the fluid physics of twisting Oreo cookies

“Our study helps determine the strength of the shocks, the position of the shocks, and the vortices that are created inside the dishwasher,” adds co-author Dr Laila Abu-Farah, from the Technical University of Munich, Germany.

“These things are very important for arranging the items or objects inside the dishwasher and the placement and orientation of the nozzles.”

The simulations found the shock waves could kill 99% of heat-resistant bacteria on a plate, in 25 seconds. The researchers think it would take slightly more time to remove food debris or wash more than one dish at a time, but they’re confident both are possible.

Graph of time in seconds versus bacteria concentration ratio, line decreases exponentially from 1 at 0 seconds to almost 0 at 30 seconds
Bacteria concentration on the plate within the dishwasher over time. The superheated steam kills off the bacteria within 25 seconds. Credit: Laila Abu-Farah and Natalie Germann

While the superheated steam dishwasher would cost more to make than a conventional dishwasher, the researchers believe it would pay for itself in savings from water, electricity, and detergent. The researchers suggest it would be useful in commercial applications, like restaurants and hospitals.

“We confirmed that the dishwasher application using superheated steam is promising,” says Germann.

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