CWD: Next Gen Combined Washer and Dryer Platform for Higher Efficiency and Fast Operation

In this proposed project, Oak Ridge National Laboratory (ORNL), in partnership with an industrial partner, will develop a compact, combination clothes washer and dryer. The dryer will utilize both a heat pump cycle and thermal energy storage to increase the energy efficiency of this class of domestic appliance. Combined clothes washer and dryer units, typically in a stacked configuration with the dryer unit located above the washer unit, are attractive in applications where space is limited, such as apartments or condominiums. The existing product line for the combined washer and dryer relies on an electric resistive heating system for the drying process, and this method of heating accounts for the bulk of their energy consumption. A significantly more efficient heat pump cycle can be used to provide the heat required for drying, however, implementation of a heat pump cycle poses a challenge due to the longer duration of the drying process. In this project, a heat pump and embedded energy storage will provide a cost-effective solution where a relatively smaller-capacity heat pump system can be operated to store heat before the drying process begins. This allows multiple benefits including recovery of waste heat during the washing cycle, a relatively shorter drying operation, and a higher combined energy factor (CEF) compared to existing technology.

First, ORNL will evaluate different system configurations, considering performance, footprints, and initial costs. ORNL will also identify potential modifications to components to maximize overall performance and enable equal or smaller footprints for the combined unit. Next, ORNL will optimize the size of the heat pump and the thermal energy storage system to achieve a minimum of 20% reduction in heat pump capacity compared to a standalone heat pump dryer. Finally, energy savings and reduction in CO2 emissions will be evaluated, and opportunities will be identified for cost reduction with the combined platform.

Project Impact

This project will demonstrate a low-cost combined washer and heat pump dryer platform with a higher combined energy factor, CEF (>25% improvement), compared to existing electric resistance dryers and with faster operation (>20% reduction in overall operating time) compared to state-of-the-art heat pump dryers. Today, state-of-the-art heat pump dryer has an estimated energy test cycle time of 71 minutes, an estimated annual energy use of 531 kWh/yr, and combined energy factor of 4.5.