Analysis and Optimization of Home Appliances Hydraulic Systems

Energy efficiency, environmental sustainability and reliability are international goals in matter of home appliances. Regulations and standards, such as energy labelling and ecological footprint, are continuously updated and improved. Home appliances such as washing machines and dish washer, are used daily by consumers, and this has important impacts on overall energy consumption, water consumption and substances released in the environment. This work main objectives are to study fluid dynamic behaviours that occur in home appliances hydraulic systems. Acknowledging these phenomena can bring serious improvement and optimization in the appliance functionality in terms of efficiency, sustainability and reliability. The research has been carried out within Electrolux Italia SPA R&D department and was mainly focused on washing machines hydraulic systems. The main application of the study is developing new technologies for WM hydraulic systems. One example of a new functionality, which is current topic of discussion, is the introduction of a fine mesh filtering system to capture micro plastic fibres released from clothes. This filtration system is necessary to prevent plastic fibres from being released in the environment. These fibres end up in our oceans and seas, because wastewater treatment plants are not able to retain them. Such fine filtration mesh represents a challenge for the current drainage system of washing machines. This system is already optimized to not be clogged but still be able to retain smaller objects that could end up in the laundry load. Another example is the design of new solutions for auto-dosing detergent dispensers. The said dispenser has to optimize the quantity of detergent for a certain type of laundry load and still maintaining flexibility in its use and reliability when misused. In this dissertation, specific components are analysed from a fluid dynamic point of view. Different components require different approaches in terms of topological optimization. During this work hydraulic optimization is performed on different levels of details, from a wider approach considering the biggest and most relevant geometry parameters, to small scale fine tuning. Different levels in details imply also different sets of given constraints and with them different levels of uncertainty. Stochastic optimization algorithm can be applied with higher degrees of freedom in the optimization domain, while for detailed refinement of a feature, a DOE approach is more effective. In this dissertation, these optimization processes are coupled with CFD analysis, rapid prototyping and testing. This allows further validation of the optimized solution as well as some important insights on the complex phenomena that cannot always be predicted with numerical models.