Determination of equilibrium isotherms and proper mathematical model for lime slices

Abstract

Equilibrium moisture content (EMC) at different air relative humidity and temperatures is a vital parameter in optimization of drying and storage processes. In the present study amount of moisture content in lime (Local variety) slice at different ambient temperatures of 30°C, 40°C and 50°C were measured using gravimetric method. The obtained E.M.C experimental values were employed to plot the isotherm curve at different environmental air temperatures. These data also were fed to fourteen popular mathematical models. The well-known statistical factors such as Coefficient of determination (R^2), Chi-square (χ2), Root of mean square error (RMSE) and Mean of relative deviation (MRD) were calculated to validate the goodness of fit. The Peleg Model was selected as the best model for predicting the EMC at each three temperatures level. The result of present research displayed that the amount of EMC decreased with increasing the ambient temperature. The monolayer moisture content (m0) was also determined using Brunauer, Emmett and Teller (BET) equation. The monolayer moisture content values were 0.023, 0.021 and 0.014 g.H_2 O/g solid at 30°C, 40°Cand 50°C, respectively, and the corresponding constant values of the Brunauer, Emmett and Teller equation were found to be −4.925, −6.543 and −7.035, respectively.