Improvement of conventional solar drying system

This research proposes a combined-drying system as a design solution to improve the performance of conventional solar drying systems in terms of the uniformity of taste and humidity remain in dried crops thanking to controlled and stabilized drying parameters. The design is an active solar drying type in which the even distribution of hot air flow over the crops is emphasized and made possible by a special chamber geometrical structure; and drying parameters including chamber indoor temperature; humidity and air velocity are controlled within specific value ranges by a relevant automatic control system. Three kinds of crops, including jackfruit, banana and bitter-melon have been tested. Results have shown that the design actually maintained well the set values of drying temperature and air flow rate while the chamber's structure did help distribute the heat evenly on the crops. The taste of the dried crops was practically examined by experts and confirmed to be excellent, and humidity remain in the crops was quite uniform with only 1.5% difference maximum. Besides, although daily weather condition does affect on the contribution of the absorbed solar energy, in the testing condition, it contributed around 59% of the total energy consumption.