BSH is using the absorption properties of zeolite to improve the drying performance in its dishwashers.
European appliance maker BSH Bosch und Siemens Hausgeräte GmbH (Munich, Germany; www.bsh-group.com) and The Bavarian Center for Applied Energy Research (ZAE Bayern) have jointly developed an innovative dishwasher drying system that is said to improve drying results and save energy.
The system is based on a silicate mineral called zeolite. According to Michael Rosenbauer, director of research and development, BSH Dishwasher, the mineral’s characteristic of absorbing water molecules and then releasing them as the temperature rises makes it very useful for industrial purposes, especially in dishwasher drying.
Rosenbauer explains: “The zeolite is held in a container under the dishwasher’s interior compartment—a filling and venting pipe connects the two together. The system is activated during the dishwasher’s drying phase. At the end of the last rinse, steam rises from the heated dishware and utensils. The warm, humid air is conducted from the interior compartment downward into the zeolite container. The mineral absorbs the moisture and, in doing so, releases heat energy. The now hot, dry air is redirected into the interior compartment and dries the dishes, glassware, and utensils much faster than our current drying systems.”
The system is also said to improve the drying of plastic dishware, keeps dishes from getting too hot upon completion of the wash cycle, and eliminates the steam that typically releases after the dishwasher door is opened.
While zeolite is available naturally, the BSH system uses a synthetic form which is common in industrial applications. Rosenbauer says that working with ZAE Bayern helped the appliance company understand the physical/chemical characterization of the mineral. The two organizations also worked together on the design of the absorption process.
Building on the resulting innovation, BSH has also discovered a way to use the energy necessary to regenerate the zeolite to also heat the water in the next run of the dishwasher. “With each new washing cycle, the zeolite regenerates during the normal dishwasher operation,” Rosenbauer says. “Air is thereby conducted from the interior compartment to a heating element, heated, and then directed further through the zeolite granules, releasing the previously absorbed moisture. The hot, moist air flows back into the dishwasher interior, where it helps quickly heat the dishware. A prime example of renewable energy.”