Effect of shape and size on convective mass transfer coefficient during greenhouse drying (GHD) of Jaggery

In this communication an attempt has been made to evaluate the convective mass transfer coefficient during drying of Jaggery in a controlled environment for natural as well as forced convection. For this purpose, different dimensions i.e., 0.03 × 0.03 × 0.01 m3, 0.03 × 0.03 × 0.02 m3 and 0.03 × 0.03 × 0.03 m3, of Jaggery pieces were taken. Two set of experiments with total quantity of Jaggery as 0.75 kg and 2.0 kg were done for each dimension of Jaggery pieces. The Jaggery was dried in the roof type even span greenhouse with floor area of 1.20 × 0.78 m2 till there is almost no variation in its mass. Experiments were carried out during the months of February 2004 to March 2004 inside the greenhouse at IIT Delhi (28°35′ N 72°12′ E) from 10am to 5pm. Values of the constant, C and n were obtained, from the experimental data of mass evaporated, temperatures of Jaggery, greenhouse room air and relative humidity, by regression analysis and finally the convective mass transfer coefficient was evaluated. It is observed from the present study that convective mass transfer coefficient is more for the Jaggery pieces having dimensions 0.03 × 0.03 × 0.02 m3 in natural mode of convection while in forced mode it is more for the Jaggery pieces having dimensions 0.03 × 0.03 × 0.03 m3.