Analysis of dryer performance for the improvement of small-scale litchi processing

Summary Litchi is a significant cash crop in Thailand, but marketing is constrained by the perishable nature of the fruit. Drying can extend the shelf life of the fruit; however, in Thailand drying technology is still in its early stages of development. With the aim of improving locally available small‐scale drying equipment, the performance of a litchi batch‐dryer by a farmers’ cooperative near Chiang Mai was studied. Drying conditions, energy consumption and product quality were monitored over three trials. Energy performance was analysed using instantaneous indices, leading to suggestions for possible design‐modifications. About 29.8% of the heat input was used for moisture evaporation, 38.4% was lost via unsaturated exhaust air and 17.6% was lost to the ambient environment. An optimum air flow rate, one that minimises exhaust heat losses without increasing the drying time, was calculated. Temperature and air flow within the drying chamber varied, resulting in a non‐uniform batch. To improve performance, a new design for the drying chamber air inlet is recommended.