Measured Performance of Residential Dehumidifiers Under Cyclic Operation

Residential construction practices are progressing toward higher levels of energy efficiency. A proven strategy to save energy is to simultaneously increase building insulation levels and reduce outdoor air infiltration. Tight homes require intentional mechanical ventilation to ensure healthy indoor air. Overall, this strategy results in a shift in the mix of latent and sensible space conditioning loads, requiring proportionally more moisture to be removed compared to standard homes. There is currently not sufficient information available at a wide enough range of operating points to design dehumidification systems for high performance homes in hot-humid climates. The only industry information available on dehumidifier moisture removal and energy consumption are performance ratings conducted at a single test condition, which does not provide a full representation of dehumidifier operation under real-world conditions. Winkler et al. (2011) developed steady state performance maps to predict dehumidifier performance at a variety of indoor conditions. However, installed heating, ventilating, and air-conditioning (HVAC) equipment rarely operates at steady state. Part load performance testing of residential dehumidifiers is not mandated by current test standards. Therefore, we tested the part load performance of four residential dehumidifiers in the National Renewable Energy Laboratory's (NREL) Advanced HVAC Systems Laboratory . The part load efficiency of each dehumidifier was measured under 13 cycling scenarios, and combined with NREL field data to develop part load fraction (PLF) performance curves under realistic cycling scenarios.