Drying of Spirulina with a continuous infrared-assisted refractance window™ dryer equipped with a photovoltaic-thermal solar collector

Abstract

Drying is one of the effective techniques in increasing Spirulina shelf life. Performance of a continuous infrared-refractance window (TM) dryer coupled with a double-pass photovoltaic-thermal (PVT) solar collector was investigated at different drying air flow rates (0.036, 0.071, and 0.107 m(3)/s/m(2) collector) and Spirulina feeding rates (1.2 L/h, 1.8 L/h, and 2.4 L/h). The maximum electrical and thermal efficiencies of the PVT collector, solar electricity fraction, and solar heat fraction were found to be 11.91%, 68.47%, 0.76, and 0.78, respectively. The average specific energy consumption values ranged between 1.21 and 2.437 kWh/kg. The yellowness index (b*) of the dried products decreased by 63.67%, and the redness index (a*) increased by 39.4% when the feeding rate was increased from 1.2 to 2.4 L/h. The highest phycocyanin content was approximately 11.4 g/100 g at the feeding rate of 2.4 L/h and the air flow rate of 0.107 m(3)/s/m(2) collector.