INVESTIGATION OF INDIRECT SOLAR DRYING OF GINGER RHIZOMES (ZINGIBER OFFICINALE): A COMPARATIVE STUDY

In this communication, an attempt has been made to investigate the drying kinetics of ginger rhizomes under natural and forced convection indirect solar drying modes. Various experiments were conducted during the months of March and April 2014 in the climate conditions of Hisar (29 degrees 5'5''N, 75 degrees 45'55''E), India. The data thus obtained for natural and forced convection drying modes was used to determine the constants 'C' and 'n' in the Nusselt number expression through linear regression analysis. Based on the values of these constants, the convective heat transfer coefficients for natural and forced convection drying modes were evaluated and reported to vary from 0.59 to 5.42 W/m(2)degrees C and 2.52 to 6.33 W/m(2)degrees C, respectively. As compared to the natural convection drying mode, the average collector efficiency and moisture removing rates were obtained to be higher under forced convection drying mode. Further, the experimental errors in terms of percent uncertainty were also determined.