Proceedings of The 7th International Conference on Innovation in Science and Technology
Experimental Investigation on Thermal Efficiency of Indirect Forced Convection Solar Tunnel Dryer
A. Sotoodeh, A. S. A. Hamid, A. Ibrahim, K. Sopian
This paper aims to evaluate the performance of a small-scale indirect forced convection solar tunnel dryer and more specifically the thermal efficiency of the said dryer. The solar tunnel dryer (STD) which is one of the common types of dryers utilizes sunlight to dry various agricultural products. The STD which is a semi-cylindrical and energy saving dryer is able to operate in remote areas. The performance of solar tunnel dryers depends on different contributing factors such as air convection mode, solar irradiance, ambient temperature and relative humidity, air velocity and load’s features. In order to investigate and find the optimum thermal efficiency, variable and constant airflow velocity were tested and their thermal efficiencies were obtained. It was found that, at no-load condition, the maximum thermal efficiency for variable airflow velocity was 26.3 % and for constant 7m/s airflow velocity the figure was 52.4 %. The average absorber inlet and outlet temperature were 32.9 oC and 62.1 oC, and relative humidity were 50 % and 27.4 % respectively. The maximum variable air velocity was 6.3 m/s at an irradiance of 886 W/m2 during the daytime. In addition, the total solar energy available, peak sun hour, and input energy were determined as 5.5 kWh/d, 5.5 h, 19.3 kWh respectively.
Keywords: Thermal energy, solar tunnel dryer, dried fruit, experimental study.