Diagram of a new thermoelectric clothes dryer.

A new thermoelectric clothes dryer being developed by Oak Ridge National Lab and Sheetak, Inc. could yield a 38% reduction in energy use compared to current dryers, which could save 356 TBtu of energy per year.

This article originally appeared in the Oak Ridge National Laboratory Building Technologies Update Newsletter April 2016 Issue (URL: www.ornl.gov/buildings → Media → News)

A collaborative effort between ORNL and Sheetak, Inc., has resulted in prototypes of a novel thermoelectric (TE) clothes dryer that is energy efficient and has a potentially short payback period. The solid-state heat pump technology is expected to deliver an energy factor greater than 6 lb/kWh, a major improvement over current electric resistance dryers, which perform at only 3.73 lb/kWh.

A research team led by the Building Technologies Research and Integration Center’s Kyle Gluesenkamp built two prototypes to investigate two configurations: (1) a drum-integrated model that reduces the temperature lift of the heat pump and lessens the impact of lint and (2) an air-based model that has a shorter drying time but comparable efficiency.

In the drum-integrated prototype, TE heat pump operation was simulated using electric resistance heaters and a chilled water coil. The inner drum surface heats clothes by conduction, causing moisture to evaporate, which passes through to the cool (exterior) side of the drum where it condenses and drains off. In the full TE version of this prototype, drum-integrated TE modules would cool the drum exterior while simultaneously heating the drum interior.

The air-based prototype has TE elements fully implemented. Humid air leaving the drum is cooled by passing over the cold side of the TE modules, resulting in water condensation that is drained off. The cooled air is then heated by passing over the hot side of the thermoelectric modules so it can re-enter the drum as hot, dry air. This air-based configuration is expected to dry clothes in less than 30 minutes with an energy factor above 6. So far, preliminary experiments have achieved a dry time of 40 minutes and an energy factor of 4.8.

The potential impact of the new technology is significant. A 38% reduction in energy consumption in current drying methods could save 356 TBtu of energy per year nationwide. By leveraging cost-reducing TE technologies developed by Sheetak, the team is targeting an installed price premium of $80. This would mean a payback period of only 2.5 years for customers. And because no venting is needed, the unit is simpler to install than current dryers.

Not least among the potential benefits of the new dryer technology are positive impacts to the economy. Sheetak is a US-based company, and production of 15 million high-tech modules for American consumers has significant potential for job creation in domestic manufacturing up and down the supply chain. According to the American Council for an Energy-Efficient Economy, utility savings garnered from the new dryers would allow consumers to spend more on products and services from sectors of the economy other than energy, where the job multipliers and positive impact on the general economy are greater.

Learn more about this project.