The summer following my freshman year of undergrad I had a summer internship experience at Whirlpool. In this internship I worked on advanced development of dry systems for dishwashers under the supervision of Alvaro Vallejo. In particular, my project focused on the problem of top rack puddling.
Normal washing machine dry systems work by evaporation. The dry system first heats the wet, clean dishes then vents or pumps the humid air out to encourage the remaining water to evaporate. This works well for ceramics and glass, but struggles with plastics because they generally have lower thermal inertia and are worse at conducting heat. This is why after a dishwasher cycle you often still have some liquid in the bottoms of plastic cups and in parts of plastic containers. Item geometry can also prevent full drying. Many coffee mugs have a large shallow concave bottom that can collect liquid that won’t be removed during the heated dry cycle.
In my internship I ideated, built prototypes of and tested many different potential solutions to this problem of puddling in a dishwasher. The methods I investigated included a vibrating top rack, actuated tines, air blades, air blasts and water blasts. A lot of these methods were comically bad. For example airblades require a relatively powerful, high volume blower that would likely be prohibitively expensive and quite distressing to the consumer. The top rack vibration system that I prototyped was very aggressive and quite ineffective as you can see in the slow motion video footage in the video below. The air blast and water blasts were quite effective and the continued work on this system even resulted in a series of patents.