Energy efficient liquid desiccant-based dryer

Abstract

A liquid desiccant-based dryer is developed that has higher energy efficiency compared to conventional hot air based drying systems used in industrial and agricultural sectors. Two-stage regeneration of the liquid desiccant, an aqueous solution of calcium chloride, is used to improve the energy efficiency. It is demonstrated that the liquid desiccant-based dryer is techno-economically superior. Contacting device is an important component in the absorber and regenerator of a liquid desiccant system. Carryover of liquid desiccant into the process and/or regenerated air streams is eliminated with the novel contacting device, which has 120-185% greater surface density compared to conventional packing. The air side pressure drop through the contacting device is very low. This paper presents the experimental results of a liquid desiccant-based dryer, designed for a paper tray drying application. It also includes the effect of variation of operating parameters and that of solution heat exchanger on specific moisture extraction rate (SMER). The average SMER of the liquid desiccant-based dryer is experimentally found to be 1.5 kg/kW h of heat. Energy savings and resultant reduction in CO2 emissions is about 56% compared to conventional hot air-based dryer. Benefits will be more while drying temperature sensitive herbal, agricultural and pharmaceutical products. (C) 2004