A household dishwasher heated by a heat pump system using an energy storage unit with water as the heat source

• A validated simulation model of a heat pump dishwasher has been developed.
• The heat sink is the dishwasher and the heat source is a container of water.
• Most of the heat transfer from the container occurs when water freezes.
• The heat pump dishwasher uses 24% less electricity compared to a conventional.

Electricity usage by a household dishwasher can be reduced by using a heat pump system to heat the dishwasher cabinet, dishware and washing water. The evaporator obtains the energy from an energy storage unit which consists of a container filled with water which freezes to ice. The majority of the heat transfer from the energy storage to the evaporator occurs when ice is created in the energy storage unit. A transient simulation model of a dishwasher with a heat pump system was developed and compared to an experimental setup with good agreement. A simulation study of the compressor cylinder volume and the compressor operating time was performed. The results showed a 24% reduction in total electricity use compared to a dishwasher cycle using a traditional electric element.