IMPROVING THE ENERGY PERFORMANCE OF RESIDENTIAL CLOTHES DRYERS

Experiments were conducted to evaluate four techniques to improve the energy efficiency of electrically-heated domestic clothes dryers. Reduced air flow rate and heater input led to energy savings around 8%, while recirculation of a portion of the exhaust air back into the clothes dryer reduced energy consumption by approximately 18%. These two measures are attractive because of their low cost. Two modes of using an air-to-air heat exchanger for heat recovery were considered. The first is to preheat the inlet air with heat from the exhaust air, which resulted in 20 to 26% energy savings. The second mode is 100% recirculation of air through the dryer and a heat exchanger and condensation of water from this air in the heat exchanger by using indoor air. as a heat sink. This resulted in 100% heat recovery (i.e., all heat was rejected to indoors) but the energy consumption of the dryer was increased by up to 6%. To maximize energy savings, a clothes dryer with a heat exchanger can be equipped to operate in the preheating mode in the summer and in the recirculation/condensation mode in the winter. The last measure investigated recirculation, through a heat pump (i.e., dehumidifier), also resulted inmore » a 100% heat recovery and, in addition, up to a 33% reduction in dryer energy consumption, but this technique also yielded long drying times.« less