Comparative performance of coriander dryer coupled to solar air heater and solar air-heater-cum-rockbed storage

In the present communication, efforts have been made to study the drying characteristics of coriander in a stationary 0.5 tonne/batch capacity deep-bed dryer coupled to a solar air heater and a rockbed storage unit to receive hot air during sunshine and off-sunshine hours, respectively. The drying bed was assumed to consist of a number of thin layers of grains stacked upon each other. The theoretical investigation was made by writing the energy and mass balance equations for different components of the dryer-cum-air-heater-cum-storage and by adopting a finite difference approach for simulation. The results revealed that for reducing the moisture content from 28.2% (db) to 11.4% (db) the solar air heater takes 27 cumulative sunshine hours, i.e. about 3 sunshine days, whereas the solar air heater and the rockbed storage combined take 31 cumulative hours, i.e. about 2 days and 2 nights at an air flow velocity of 250 kg/hm2.