SOLAR-DRIVEN LIQUID-DESICCANT DEHUMIDIFIER/REGENERATOR FOR DRYING AGRICULTURAL PRODUCTS

摘要

Drying of agricultural products is essential for preserving product quality and achieving a long storage life and it is directed to wide range of products such as herbal plants, seeds, fruits, vegetables, forage, hay etc. Drying of agricultural products consumes significant amounts of energy usually by burning diesel or gas. An alternative drying technique is being developed to reduce energy, cost and improve product quality by replacing fossil fuel energy with a liquid desiccant absorber and solar-driven regenerator. It operates by drying with only a small increase in air temperature and a substantial reduction in the drying air relative humidity. A plate type heat and mass exchanger has been built and tested in a pilot plant stage as an air dehumidifier and desiccant regenerator. The results were analyzed and compared with a numerical model for validation. The results of the supply air adiabatic dehumidification show a consistent reduction in the relative humidity and an increase in the air temperature, which are the main factors that affect how readily moisture moves from the drying product. The parametric analysis results in reduction of the air relative humidity in the range of 18-46% points and an increase in the air temperature in the range of 3.7-8.0 K are observed, depending on the inlet parameters. The concentration of the diluted desiccant solution (from 38% to 43%) was done possible by using hot water of 55 °C, which is an optimal temperature for solar thermal collectors.