Solar, Biomass and Hybrid Dryers - BioEnergy Discussion Lists

Design detailsThis cabinet type dryer, referred to as Model FD-50, has three main components:solar collector, drying chamber, and biomass stove. The air-heating solar collector isof flat plate type, and has an absorber area of 1.9 m 2 . The drying chamber of has 30aluminum wire net trays to hold the products. An exhaust fan powered by a 45 Welectric motor fixed in the chimney of the drying chamber forces ambient air to passthrough the collector. The air thus forced gets heated while passing through thecollector, and rises up through the several trays on which the products being driedare spread in thin layers. The biomass gasifier stove assists drying whenever solarradiation is insufficient.Table 8.1: Technical specifications of the hybrid cabinet dryer FD50Sl. No. 2 Parameter Specification1. Capacity per batch 50 kg sliced fruit2. Drying time 18 hrs3. Drying air temperature up to 60°C4. Airflow rate 0.05 m 3 /hr5. Dimensions 1.4×1.0×2.69 m6. No. of trays 30 of 0.98×0.5 m7. Solar collector area 2.12×0.9 m8. Collector air gap 0.05 m9. Fuel type Coconut shell/charcoal10. Fuel consumption 2.0 kg/hrSolar CollectorThe solar collector has a matt black-coated GI absorber sheet, and a single Plexiglascover positioned about 5 cm above the absorber. The metal walls of the collector boxare insulated with 8 cm thick glass wool to reduce heat losses. The solar collectorsupplies the hot air required for dryer operation during the day time. Thedimensional details of the collector are presented in Figure 8.2.The solar collector is attached to the backside of the drying chamber at an angle of15° to the horizontal. Hot air from the collector enters the drying chamber at thebottom and rises through the several trays which hold the products to be dried. Afan inside the drying chamber assists the flow of hot air from the collector upthrough the trays.45