Experimental performance assessment of two-stage thermoelectric system in a closed-cycle drying process

Traditional drying systems suffer from several limitations, including high energy consumption, insufficient hygienic control, and the inability to maintain precise temperature regulation. Although alternative drying systems have been developed to address these issues, they often encounter practical challenges due to their complex structures and the need for numerous external components. To overcome these limitations, this study proposes and experimentally evaluates a novel, independently operating, two-stage thermoelectric module (TEM) system integrated into a closed-loop drying setup that eliminates the need for external heating and dehumidification components. The proposed system addresses the efficiency and hygiene problems observed in conventional dryers by simultaneously performing air heating, cooling, and dehumidification functions through compact thermoelectric devices. The drying process consists of two stages: the first involves air pre-conditioning (heating/cooling), while the second is dedicated to dehumidification. The performance of the system has been evaluated based on key metrics such as cooling and heating capacities, the coefficients of performance (COP) for both stages, moisture removal rate (MRR), and moisture removal rate effectiveness (EffMRR). Experimental studies were conducted under input voltages ranging from 3 to 7 V, relative humidity levels between 60 % and 90 %, and varying airflow rates. Under 90 % relative humidity conditions and a 7 V input voltage, the system achieved a maximum moisture removal rate of 13.1 g/h. The first-stage TEM reached a heating capacity of 68.81 W and a cooling capacity of 26.34 W, while the second stage provided 21.17 W of cooling capacity.