An energy efficient two-stage heat pump clothes dryer (HPCD) was successfully developed. This new dryer utilizes three advanced technologies: vapor injection cycle, compact heat exchanger and brushless direct current (BLDC) fan motor. An in-house heat exchanger design tool – CoilDesigner was utilized to design and optimize the evaporator and condenser in the vapor injection cycle. One electric clothes dryer (CD) from U.S. market was selected as the baseline product, and one hybrid HPCD from European market was selected as the best state-of-the-art commercial product in terms of energy efficiency. These two commercial products and the constructed two-stage HPCD prototype were tested according to the Department of Energy (DOE) dryer test standards. Experimental evaluation revealed that the two-stage HPCD achieved 59% energy savings and improved energy factor (EF) by 143% as compared to the electric dryer. It also achieved 25% energy savings and improved EF by 33% as compared to the hybrid HPCD. This implied that the two-stage HPCD could save energy up to 42 TW·h annually if this technology is fully deployed to replace all U.S. electric CDs. Cost analysis indicates that the payback period of the two-stage HPCD is only 2.2 years as compared to the electric dryer with bottom cabinet. Therefore, the two-stage HPCD is an economically competitive greener option.

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