Do Heat Pump Clothes Dryers Make Sense for the U.S. Market Page: 4 of 15

                                
European countries with the largest market share are Switzerland (15.6% market share) and Italy
(11% market share). Industry experts in Europe project that HPCDs should continue to gain
market share in the next few years. There are no HPCD models currently available in the U.S.
market.
Equipment Characteristics
The operation principle of heat pump clothes dryers is illustrated in Figure 1. The heat
pump is a mechanical system consisting primarily of a refrigeration loop containing a refrigerant
vapor compressor, an evaporator (a type of heat exchanger), a condenser (another heat
exchanger) and an expansion device (valve). The clothes dryer heat pump component is shown
as "1" on Figure 1.
Figure 1. Heat Pump Clothes Dryer Diagram3
Heat punup uilt
(integrated into base group)
() Heating up tte a'ir
Heating up and dehumidifying
the washing
Cooling and dehumidifying the
air and direct discharge of
R   L:.   ..    _Concfrn~ation water
A heat pump delivers heat by extracting energy from the ambient air. The hot dry
processed air enters the rear of the drum and interacts with the laundry. Warm moist air exits the
drum and proceeds through the lint screen and through the evaporator where a significant portion
of the moisture is removed before flowing through the condenser and back into the drum.
Since the evaporator removes the majority of the moisture present in the air exiting the
drum, this air can be re-circulated back into the drum. However, in steady state operation the
heat pump delivers more heat than cooling so some form of heat rejection is needed. For vented
heat pump clothes dryers, the excess heat is vented out.
Heat pump technology can be applied to both vented and ventless (condensing) clothes
dryers. All available models in Europe are ventless (Topten 2010). Currently there are no
manufactured vented HPCD models, but it is technically feasible to develop such technology
based on the development of a prototype by TIAX for Whirlpool (Pescatore 2005).

3 http://www.schulthess.ch/en/innovations/heat-pump-dryer.html