In the present work, an experimental study was performed by designing and constructing an unglazed transpired solar collector connected to an indirect solar dryer with a new design equipped with a porous plate and phase change material. Teucrium polium was considered to analysis the drying process. The experiments were conducted at two airfow rates (0.0125and 0.015kg/s) for the drying system with and without phase change material. The results implied the use of phase change material reduced the temperature of the drying chamber during the day (approximately 0.5 to 2.5◦C) compared to the collector without phase change material. In the afternoon, it increased due to presence of phase change material in the porous plate and releasing the stored thermal energy. At the airfow rate of 0.0125 kg/s, without phase change material, the highest outlet temperature of the collector was 68.8◦ C. Moreover, using phase change material reduced the specific energy consumption from 12.25 to 11.05 MJ/kg and the overall efficiency in the drying process increased from 39.48 to 42.54 %. Using phase change material increases the exergy efficiency by about 6 %. The maximum energy efficiency for unglazed transpired solar collector (about 45.92%) was related to a mass fow rate of 0.015 kg/s with phase change material. Besides, the color changes for Teucrium polium dried by solar dryer with and without phase change material were about 19.42 and 21.26. Thus, it can be expressed that the use of phase change material improved the drying and thermal efficiency and color of the dried product.
