Effect on drying kinetics and product quality of cucumber in a mixed mode solar tunnel dryer upon integration of sensible and latent heat thermal energy storage

Abstract

The effect on drying kinetics, economic characteristics and nutritional quality of dried cucumbers in a mixed mode solar dryer with both sensible and latent heat energy storage is investigated in this study. A thick bed of black pebbles at the base of drying chamber facilitated sensible heat energy storage and Lauric acid PCM filled in custom made chamber which was connected in series to the solar collector allowed latent heat energy storage. The dryer was operated without energy storage (Test 1), with sensible heat energy storage alone (Test 2) and with both sensible and latent heat energy storage (Test 3), in this study. Compared to open sun drying test 1, 2 and 3 reduced the drying time by 29.4 %, 47 % and 70.5 %, respectively. An average dryer temperature of 42.3 °C, 45.9 °C and 50.9 °C were recorded in test 1, test 2 and test 3, respectively. Rate of drying was significantly enhanced up to.76 kg of moisture per hour by integrating latent heat and sensible heat energy storage materials and also exhibited the highest drying efficiency of 14.2 %. Test 3 had the lowest payback period of 0.7 years with remarkable economic benefits compared to test 1 and test 2 configurations. The quality analysis of the products revealed higher vitamin C content in dried products from all three tests when compared to dried products under open sun, with highest retention of vitamin C reported in products from test 3.