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Will dishwashers in future no longer clean our dishes with water and detergents, but instead just with superheated steam? This is the question that Professor Natalie Germann, professor for fluid mechanics at the Department of Biochemical and Chemical Engineering of TU Dortmund University, is exploring. To this end, she has simulated a superheated steam dishwasher. The results sound highly promising: clean dishes, all bacteria killed off, fast cycle, low water and energy consumption. Professor Germann will present her findings to an international audience of experts at Americal Physical Society Conference of the Division of Fluid Dynamics (APS DFD) in Phoenix, USA, at the end of November.
Professional steam cleaners are already used on a large scale, for instance in hotels, to clean floors, windows or furniture efficiently and disinfect them in the same step. In future, this technology could also replace conventional dishwashers, which use vast quantities of tabs and salt, are unable to kill off some types of harmful bacteria despite temperatures of up to 70 °C, have long cycles and consume a lot of water. “Steam at a temperature of 180 °C cleans surfaces more thoroughly, quickly and thus more efficiently,” explains Professor Germann. “In addition, it can also kill off heat-resistant bacteria within a few seconds. This is important above all for professional use in hospitals and restaurants.”
She is working on the development of an innovative type of superheated steam dishwasher together with two industrial partners: Medeco Cleantec and Herion Engineering from Bavaria, Germany.
By means of a simulation, Professor Natalie Germann from TU Dortmund University and Dr. Laila Abu-Farah from the Technical University of Munich (TUM) have studied the potential of superheated steam. Firstly, it was a matter of understanding the physical processes: How powerful is the steam’s effect in the dishwasher? How far does it reach? How does it cool down, and how does it condense? Which bacteria are killed off? “Such a simulation is very complex and challenging,” says Professor Germann. As a basis for first of all simulating the turbulent flow of steam inside the appliance, the researchers used the freely available OpenFOAM software. This was combined with another software to simulate temperature and the accompanying condensation. The researchers also added a bacteria model to simulate the inactivation of bacteria on the surface of the dishes.
“The finished simulation shows the complex dynamics between flow, temperature, and bacterial inactivation in a simplified dishwasher geometry and confirms that the superheated steam does indeed clean reliably and in a short time,” says Professor Germann, summarizing the results. The findings will contribute, for example, to selecting the right arrangement of nozzles in a superheated steam dishwasher. The researchers plan to publish their results in the form of a manuscript in the international journal Physics of Fluids. In a next step, the aim is to couple the simulation with experiments to determine, among others, whether cleaning agents are still necessary at all in superheated steam dishwashers.
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Location & approach
The campus of TU Dortmund University is located close to interstate junction Dortmund West, where the Sauerlandlinie A 45 (Frankfurt-Dortmund) crosses the Ruhrschnellweg B 1 / A 40. The best interstate exit to take from A 45 is “Dortmund-Eichlinghofen” (closer to South Campus), and from B 1 / A 40 “Dortmund-Dorstfeld” (closer to North Campus). Signs for the university are located at both exits. Also, there is a new exit before you pass over the B 1-bridge leading into Dortmund.
To get from North Campus to South Campus by car, there is the connection via Vogelpothsweg/Baroper Straße. We recommend you leave your car on one of the parking lots at North Campus and use the H-Bahn (suspended monorail system), which conveniently connects the two campuses.
TU Dortmund University has its own train station (“Dortmund Universität”). From there, suburban trains (S-Bahn) leave for Dortmund main station (“Dortmund Hauptbahnhof”) and Düsseldorf main station via the “Düsseldorf Airport Train Station” (take S-Bahn number 1, which leaves every 15 or 30 minutes). The university is easily reached from Bochum, Essen, Mülheim an der Ruhr and Duisburg.
You can also take the bus or subway train from Dortmund city to the university: From Dortmund main station, you can take any train bound for the Station “Stadtgarten”, usually lines U41, U45, U 47 and U49. At “Stadtgarten” you switch trains and get on line U42 towards “Hombruch”. Look out for the Station “An der Palmweide”. From the bus stop just across the road, busses bound for TU Dortmund University leave every ten minutes (445, 447 and 462). Another option is to take the subway routes U41, U45, U47 and U49 from Dortmund main station to the stop “Dortmund Kampstraße”. From there, take U43 or U44 to the stop “Dortmund Wittener Straße”. Switch to bus line 447 and get off at “Dortmund Universität S”.
The AirportExpress is a fast and convenient means of transport from Dortmund Airport (DTM) to Dortmund Central Station, taking you there in little more than 20 minutes. From Dortmund Central Station, you can continue to the university campus by interurban railway (S-Bahn). A larger range of international flight connections is offered at Düsseldorf Airport (DUS), which is about 60 kilometres away and can be directly reached by S-Bahn from the university station.
The H-Bahn is one of the hallmarks of TU Dortmund University. There are two stations on North Campus. One (“Dortmund Universität S”) is directly located at the suburban train stop, which connects the university directly with the city of Dortmund and the rest of the Ruhr Area. Also from this station, there are connections to the “Technologiepark” and (via South Campus) Eichlinghofen. The other station is located at the dining hall at North Campus and offers a direct connection to South Campus every five minutes.
The facilities of TU Dortmund University are spread over two campuses, the larger Campus North and the smaller Campus South. Additionally, some areas of the university are located in the adjacent “Technologiepark”.