Experimental Studies of Effects of Geometry on Drying Rate and Properties of Ginger (Zingiber officinale Rosc.) with Solar-hybrid Dryer

Abstract

Poor drying and processing methods employed by Nigerian farmers have led to loss of quality of dried ginger produced. Therefore, there is need to improve the drying and processing methods so that the quality of the products will be improved. To achieve this, a natural convection solar dryer was designed and constructed to dry ginger slices in different geometries. A 3 kg capacity hybrid dryer which was solar and biomass fueled was designed. The ginger samples were grouped into peeled and unpeeled. The specimens (peeled and unpeeled) were cut into cylindrical (Ø 0.2 m, thickness 0.008 m) and rectangular (0.03 x 0.025 m, thickness 0.008 m) shapes and 2.7 kg each were dried using open air, solar assisted and hybrid dryer. The initial and final moisture contents considered were 82.3% and 10% (wet basis), respectively. The average ambient conditions were 30 ºC air temperature and 15% relative humidity with daily global solar radiation incident on horizontal surface of about 20MJ/m² /day. The weather conditions considered are of Ogbomoso, Nigeria. A prototype of the dryer is so designed and constructed that has a maximum collector area of 1.03m². The percentage essential oil retention of cylindrical was higher than that of rectangular.

Keywords: Solar biomass dryer, Ginger, geometry, drying, essential oil Radiation