18 May 2017

P.4.9.2 Thermoelectric heat pump clothes dryer design optimization

Clothes dryers based on thermoelectric (TE) heat pumps have the potential to save significant energy compared with the conventional electric resistance technology that is widespread today, without using any refrigerant fluid. In this work, guided by a validated system model, design and control improvements were implemented on an experimental prototype to optimize the dryer performance (duration to dry a load, and energy consumed per unit cloth mass). Starting from a fixed TE area, the physical design variables of interest were (1) the use of vented or ventless configuration, (2) the heat sink geometry, (3) the selection of blower and (4) the selection of motor used to drive drum rotation. The control variables of interest were (5) the average electrical current supplied to each bank of TEs and (6) the current profile for each bank during the drying time. By optimizing each of these choices in the model and applying the resulting design choices on the prototype, the experimentally measured efficiency of the TE prototype was improved to 2.96 kg/kWh (6.52 lb/kWh), 38% better than an Energy Star qualified electric resistance dryer, and within 14% of a vapor compression heat pump clothes dryer.