Experimental comparison of heat and mass transfer characteristics between washer-dryer and dryer drums during the drying process

초록

All-in-one washer-dryer units suffer from inferior drying performance compared with conventional tumble dryers because air is bypassed through the holes in the inner drum required for the washing process. However, comprehensive studies on the relationship between drum-level heat and mass transfer characteristics and drying performance of the washer-dryer remain limited. In this study, the heat and mass transfer characteristics of washer-dryer and dryer drums were measured and compared under various inlet air temperature, absolute humidity, and airflow rate conditions. The heat and mass transfer behaviors within the washer-dryer drum were consistent with those of the conventional dryer drum, including the effects of moisture content, air temperature, humidity, and airflow rate. However, the washer-dryer drum exhibited 7.8%-20.3% lower mass transfer rates and 12.2%-23.2% lower sensible heat transfer rates than the dryer drum. These performance degradations in the washer-dryer drum are attributed to the bypassing air through the holes in the inner drum, which weakens air-fabric heat and mass exchange. Several blockage configurations with sealing selected holes between the inner and outer drums were evaluated to mitigate this limitation. When approximately two-thirds of the side holes were blocked while maintaining the airflow rate, the mass and sensible heat transfer rates increased by 7.9% and 8.3%, respectively, compared with the base washer-dryer drum. These results indicate that optimizing the drum hole configuration can enhance the drying performance by promoting deeper airflow penetration toward the rear of the drum while suppressing bypass air.

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