World first: Economical drying using solar power

Using direct radiant heat from the sun to dry laundry has, to date, only been possible by hanging washing out on a washing line. In future, solar power can also be used to heat the process air in a tumble dryer. At the IFA 2011, Miele presented a project study compiled in co-operation with solar technology manufacturer Solvis involving a solar tumble dryer. A project particularly of interest to project developers and home owners, the solar tumble dryer is planned to be available as of early 2013.

The jointly compiled study by the two companies shows that energy produced by the sun can also be used for drying laundry in a tumble dryer – directly and with the benefit of reducing primary energy costs by up to 80%. Solar collectors on the house roof in combination with a Solvis storage tank make this possible. The principle operation of the installation is as efficient as its sophisticated technology; the freeze-protected fluid in circulation in the collectors transfers its heat load to the water in the storage tank. Temperature stratification in the tank means that a variety of water temperatures are available for a variety of uses. Water with the highest temperature is used for the tumble dryer, the same as used to heat tap water. The solar dryer is connected to the stratified storage tank via four lines which form a closed circuit. Thanks to this closed circuit, the system is virtually loss-free, as for the most part the heat extracted for drying laundry is re-introduced to the storage tank in the condensation process.

Positive side effects of this technology are that whilst in the future home solar-thermal collector systems are more utilised, and therefore more economical, stored water can be heated in the less sunny Winter months, using regenerative sources which are independent from solar radiation. Drying laundry this way is easier on resources during the dark season. The consumer benefits are obvious: users demonstrate a strong sense of responsibility when using scarcer resources and at the same time reduce the strain on financial budgets.