NATURAL CONVECTION MODE SOLAR DRIER INTEGRATED WITH HEAT STORAGE UNIT

An indirect mode natural convection double pass solar dryer integrated with heat storing unit was designed and constructed with the loading capacity of 1kg to evaluate the performance using lady's finger as a crop. This paper presents a performance of collector with heat storing unit (HSU). In HSU, PCM (Paraffin Wax) used as the heat storing medium. The experiments were conducted with loading of 1 kg of Lady's finger having the initial moisture content of 95% wet basis from which 0.9 kg of water is required to be removed until the safe moisture content of 10% wet basis during Oct-November 2016 in Salem, Tamil Nadu. The nominal surface area of all types of absorber plate is 0.5 m square but effective surface area varies with configuration. The drying time was taken around 15.6 hours with flat plate but it was taken only 13.4 hours with attachment of HSU. Thus around 2 hours of drying time was reduced by using HSU than flat plate and also the collector efficiency range was improved from 2.6-7.13% in flat plate to 4.2-15.4% in HSU. Also the quality of the dried Lady's finger was much superior compared to open sun drying.