Hot steam dishwasher model more effective, environmentally-friendly
Superheated steam dishwashers developed by researchers from the Technical University of Dortmund and the Technical University of Munich, both in Germany, were more effective than conventional dishwashers when it comes to killing harmful microorganisms on dishes and cutlery.
According to reports, a model of a superheated steam dishwasher apparently eliminated 99% of bacteria on a plate in just 25 seconds. The model consists of a box with solid side walls, a top opening, and a nozzle at the bottom. A plate covered with a heat-resistant strain of bacteria is placed directly above the nozzle. Once the plate reaches a certain threshold temperature in the simulation, the microorganisms are deemed inactivated.
High velocity of the steam coming out from the nozzle creates shock waves which are reflected at surfaces in the dishwasher – the researchers postulate the shocks could be used to remove food debris, to be experimented on in the future.
“We can see shocks, and the turbulent flow that is created has eddies and vortices. We also include heat transfer, which shows how the heat changes in the simulation box and the condensation on the solid surfaces,” said Professor Natalie Germann, of the Technical University of Dortmund.
While the simulations show quick inactivation of the bacteria, actual applications of the dishwasher would include more than one plate and therefore require more time. However, the researchers believe it would still be much faster and more effective than conventional technology.
“Our study helps determine the strength of the shocks, the position of the shocks, and the vortices that are created inside the dishwasher,” added Laila Abu-Farah, of the Technical University of Munich. “These things are very important for arranging the items or objects inside the dishwasher and the placement and orientation of the nozzles.” While superheated steam dishwashers would initially cost more than conventional dishwashers, it would pay off in the long run with compound savings on water, electricity, and detergent. Superheated steam dishwashers would be ideal for use in restaurants, hotels, and hospitals, which must meet high hygienic standards.
