Design, Development and Performance Evaluation of Solar Dryers

• Main Authors: Ho Xuan-Lam, 胡春林
• Other Authors: 陳長仁
• Format: Others
• Online Access: http://ndltd.ncl.edu.tw/handle/28xyum

碩士 === 崑山科技大學 === 機械工程研究所 === 95 === Mechanical drying of agricultural products is an energy consuming operation in the post-harvesting technology. Greater emphasis is given to use solar energy sources in this process due to the high prices and shortages of fossil fuels. The performance characteristic of the new design of solar drying system shows that the ability of being used by customers is really high for its simple structure and installation. For these purposes a new nature convection type dryer, a new forced flow type dryer and new electric dryer was developed for drying food products. The presented drying system was successfully tested using banana chips for nature convection dryer and forced flow dryer experiments have been performed to investigate the performance evaluation & drying behavior of the banana fruits and comparisons between experimental results showing that good agreement has been achieved. This solar nature convection dryer reduced the moisture content of the banana chips to desired levels from about 75-85% to 7-10% and drying chamber efficiency of dryer was 18.23% and forced flow dryer reduced the moisture content of the banana chips up to desired levels from about 75-85% to 7-8%. The overall thermal efficiency of the forced drying unit obtained was 30.86% for the five day drying experiments since 9.00 hrs to 16.00 hrs. The qualitative analysis showed that the traditional drying, i.e. shade drying and open sun drying, dried the samples in 15 and 7 days respectively, while the solar dryer took only 5 days and produced better quality of dried samples. For comparison experiments with the electric drying system were also successfully tested using banana chips, mangoes slice & sweet cherries. The experiments have been performed with different temperatures of fruit drying to investigate the drying behavior of the fruits. This electric dryer reduced the moisture content of the fruits to desired value from about 75-85% to 15-18%. It was shown that the use of this type of electric dryer reduced the drying time significantly and essentially provided better product quality.