Model-Based Energy Efficiency Optimization of a Low-Temperature Adsorption Dryer

Low-temperature drying is important for heat-sensitive products, but at these temperatures conventional convective dryers have low energy efficiencies. To overcome this challenge, an energy efficiency optimization procedure is applied to a zeolite adsorption dryer subject to product quality. The procedure finds a trade-off between the improved drying capacity due to dehumidification and energy expenditure due to regeneration while incorporating product drying properties. By optimizing the regeneration air inlet temperature, drying air, adsorbent, and regeneration air flow rates as well as sensible and latent heat recovery from the regenerator exhausts, the energy efficiency is improved by up to 45% compared to the state-of-the-art. The high mass transfer effect of high temperatures is utilized in the regenerator to boost dehumidification while isolating the heat-sensitive dried product from the quality-degrading effect. A process optimization procedure for maximizing energy efficiency is applied to a zeolite adsorption dryer subject to product quality. By optimizing the regeneration air inlet temperature, drying air, adsorbent, and regeneration air flow rates as well as sensible and latent heat recovery from the regenerator exhausts, the energy efficiency is improved by up to 45% compared to the state-of-the-art. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.