Drying Performance of Integrating Mesh Wire as Drying Space into the Inflatable Solar Dryer for Drying Coffee

The drying performance of coffee laid in a mesh wire that serves as a drying space in an inflatable solar dryer (ISD) was evaluated and compared to open sun drying (OSD) and ISD without mesh wire drying space in the Philippines. Condensation was observed in ISD due to the moisture content of the crops and solar radiation, which affected the drying time. Thus, mesh wire was introduced to reduce moisture buildup inside the ISD. The drying time was determined upon reaching the ideal moisture content of 12% for coffee.

The dryer was composed of a solar-powered fan, a solar air heater, and an inflatable solar dryer with mesh as a drying space. Three batches of 16.3 kg of fresh coffee were dried in each dryer. The temperature inside the ISD was measured using a data logger humidity and temperature sensor, and the coffee's weight was determined using a digital weighing scale.

The experiment trial demonstrates that an ISD with a mesh wire dramatically reduces drying time and prevents mass losses. Besides, product quality improved significantly because mesh wire aids in straining unwanted particles from the crops. The coffee is completely protected from rain, dust, insects, and animals during drying, resulting in high-quality products. The material costs associated with adding mesh wire into the ISD are insignificant when compared to the additional earnings generated by reduced mass losses and fastest drying time. Due to the solar-powered fan, the dryer can easily be operated by farmers and is reliable even when off-grid.