A nonmechanical solar dryer based on convective heat and mass transfer has been constructed to investigate the drying characteristics of various products such as grapes, onion and okra, using a simple solar dryer with forced ventilation for the case of onion and grapes solar drying or natural ventilation for the case ofokra solar drying where solar heating is achieved by radiation and convection heat transfer. The dryer is constructed from locally available materials and operates on solar energy. Different tests were conducted for loading and unloading. The configuration is modeled and the simulation results are obtained. The model is verified by comparing the simulation results with the experimental data. The moisture loss during the drying process can be described by a general equation of the form dM/dt = -cM. The drying constants Cl and C2 for the constant and falling rate periods are calculated. Grapes and onion have constant and falling rate periods, while okra has only falling rate period. |
