DEVELOPMENT AND ANALYSIS OF HYBRID SOLAR DRYER WITH BIOMASS BACKUP HEATER

• Main Author: MD YUNUS, YUSHEILA
• Format: Thesis
• Language: English
• Published: 2011
• Online Access: http://utpedia.utp.edu.my/3060/1/Msc___Yusheila.pdf; http://utpedia.utp.edu.my/3060/

The application of solar drying, especially in the agricultural areas, has been proven to be practical, economical, and environmental friendly. However, the drying process is limited only on a sunny environment and often interrupted during the cloudy or rainy days and also at night. A hybrid dryer with thermal backup technique has been adopted to overcome the limitation of solar dryer. The combination of the systems is expected to create 24 hours a day of non-interrupted drying process. The study on the drying system was carried out by three analysis techniques; analytical, experimental and numerical. The conceptual design of the experimental model was based on analytical modeling of the drying process using solar, or the backing up heat source, or both of them simultaneously. The work was extended to involve numerical simulation of the fluid flow inside the developed hybrid dryer by employing CFD technique using FLUENT® software under different operational modes. Chillies and empty fruit bunch (EFB) as food and waste product respectively has been selected for the materials to be dried. They were dried under different modes, which were ‘only solar’, ‘thermal backup alone’ and ‘solar-thermal backup’ (hybrid). Open sun drying was also conducted and considered as a reference for comparison. It was found that the fastest drying process was in the hybrid drying mode. Moisture content of chillies and EFB were reduced from 80% to 5% and 75% to 6% within 2.33 and 1.33 days of drying, respectively. The hybrid drying efficiencies of chillies and EFB were considerably high as compared to only solar and thermal alone mode which were 6.85% and 11% respectively. The experimental measurements have shown good agreement with the simulated results, with maximum percent of error of 15%. Hybrid mode was the most appropriate mode for drying application since it meets the required drying temperature. Also, it was capable to reduce the drying period considerably. The simulation results were validated by comparing with the experimental measurements.