"Design And Development Of Direct Passive Solar Dryers With Blue, White And Yellow Glazing Materials For Drying Of Herbs":- Benjamin Uchechukwu G

ABSTRACT

The research presents the design and development of three direct passive solar dryers with blue, white and yellow glazing colours incorporated with pebbles as thermal storage material placed on the absorber plate. The dryers were operated and tested under ambient conditions of temperature and relative humidity ranges of 30.6°C - 44.3°C and 54.7%-24.9% respectively. Dryer with yellow glazing recorded the highest average drying temperature and lowest average drying chamber relative humidity of 37.68°C and 39.06% respectively followed by white and blue glazing dryers of values 37.6°C and 37.1°C with corresponding average relative humidity of 39.56% and 39.99%. This result reflected in the drying rates of bitter leaves and lim tree leaves used in testing the dryers. Statistical analysis at 5% probability level showed that glazing colours and drying time had significant effect on the moisture content level of bitter leaves and lim tree leaves. Moreover, colour analysis of the dried bitter leaves and lim tree leaves showed that yellow glazing dryer recorded the best colour code values closest to natural green with values of 165 out 255 in lim tree and 85 out of 255 for bitter leaves on natural green colour coding scale compared to white and blue glazing dryers.