Concept study of a new method for drying dishware in a heat pump dishwasher

Abstract

In a heat pump dishwasher, the whole dishwasher with the cabinet, dishware and process water is the heat sink, while a water tank, whose contents will freeze, is the heat source. The aim of the experimental concept study presented here was to evaluate a new drying method for a heat pump dishwasher. In this method, the drying of the dishware occurs as a fan circulates humid air in a closed system in which the water on the dishware evaporates inside the warm dishwasher cabinet and then condenses on a cold surface of the frozen water tank. The evaluation of drying performance was based on the European standard EN50242, which considers visible water drops left on the dishware after a completed dishwashing cycle. The results showed that this new closed drying method was more energy efficient compared to an existing open drying method and that the drying start temperature and the drying time had a significant effect on the drying performance. Its lower electricity consumption and the fact that it does not vent humid air into the kitchen give this heat pump dishwasher a competitive advantage over dishwashers using an open drying method.