Abstract

Yerba mate is an herbal tea produced in the central part of South America. One of the main steps of the process is drying. Among the different types of dryers which are used at present, the double pass belt conveyer dryer is the most energy efficient. The increase in wood prizes used as fuel, has generated a demand from industrial producers to improve the thermal efficiency of the process. In order to do this, a numerical model of a double deck dryer of yerba mate has been developed to study the way of improving the energy efficiency and propose modifications to the present working conditions in industry. The good of fitness of the model was determined using experimental data from two industrial dryers. The results of the model were that using hot air at 100 °C and a solid mass flow rate of 4,000 kg/h, the energy efficiency was of 40.60%. Simulating the process at different drying conditions, it was found that the energy efficiency of the dryer could be improved by recirculating 15% of the exhaust air (63.70%), or drying at 120 °C and using a higher solids mass flow rate of 6,200 kg/h with an energy efficiency of 46.21%.

摘要

Yerba mate 是一种产于南美洲中部的凉茶。该过程的主要步骤之一是干燥。在目前使用的不同类型的干燥机中，双通道带式输送机干燥机是最节能的。用作燃料的木材价格的增加已经引起了工业生产商提高工艺热效率的需求。为了做到这一点，已经开发了一种马黛茶双层烘干机的数值模型，以研究提高能源效率的方法，并提出对当前工业工作条件的修改。使用来自两个工业烘干机的实验数据确定了模型的拟合度。模型的结果是，使用100℃的热空气和4000 kg/h的固体质量流量，能源效率为40.60%。