Evaluation of Convective Heat and Mass Transfer in Open Sun and Green House Drying

Abstract

In this communication, a study on open sun and green house drying has been performed to evaluate the convective heat and mass transfer coefficients as a function of climatic parameters. The hourly data for the rate of moisture removal, crop temperature, relative humidity inside greenhouse and outside greenhouse and ambient air temperature for complete drying have been recorded. The experiments were done in the premises of Allahabad Agricultural Institute-Deemed University, after the crop-harvesting season from February 2006 to April 2006. Using these data, the value of convective heat and mass transfer in open sun drying (OSD) and green house sun drying (GHD) under natural and forced convection mode, have been calculated. Also the empirical relations of convective heat and mass transfer with drying time under natural and forced modes have been developed. On the basis of the present study, it is inferred that the value of convective heat and mass transfer is more in open sun drying than in the green house drying under natural convection mode. However its value increases in forced mode of greenhouse drying as compared to natural mode in the initial stage of drying.