Energy-efficient gas-fired tumble dryer with adsorption thermal storage

Abstract Improvements to the energy efficiency of open-cycle tumble dryers have the potential to substantially reduce CO2 emissions. A novel adsorption-based thermal energy storage system is integrated into a gas-fired dryer here. An adsorbent bed is used to capture waste heat from the exhaust stream, store, and reuse it in the current and subsequent drying cycles. A heat and mass transfer model is developed to capture the dynamics of the thermal storage system, and validated experimentally on a 11.33-kg capacity gas-fired tumble dryer. The model predicts the inlet and exit temperatures of the drum with average absolute deviations of 7.1% and 8.4%, respectively. The analysis indicates that an 8.5-kg silica gel adsorption bed can yield a specific moisture extraction ratio of 1.166 k W h k g w − 1 , a 22% reduction over the energy consumption of the conventional gas-fired tumble dryer. In addition, drying time is reduced by 19%. This technology can be implemented in a variety of dryers to take advantage of the waste heat in the exhaust stream.