SELECTION OF EMC ERH ISOTHERM EQUATIONS FOR RAPESEED/

Twelve sources of equilibrium moisture content (EMC)/equilibrium relat ive humidity (ERH) data for rapeseed were identified from which 668 ex perimental points were extracted. Among them, ten sources covered a wi de range of temperatures, thus producing 21 sub-sets of data suitable for the evaluation of EMC/ERH isotherm equations. Four commonly cited rapeseed EMC/ERH equations, i.e. modified Henderson, modified Chung-Pf ost, modified Halsey and modified Oswin equations were compared for th eir ability to fit these data sub-sets based on the residual sum of sq uares (RSS), standard error of estimate (SEE) and mean relative deviat ion (MRD). The comparisons show that the modified Halsey equation is t he best equation for describing the EMC/ERH isotherms of rapeseed. The modified Halsey equation was then used to fit the data sets merging a ll the data for adsorption, desorption and the combined data set in tu rn. The best fitted coefficients for both equilibrium relative humidit y h(r)=f(M, T) and equilibrium moisture content M =f(h(r), T)are given , where T is the temperature. These fitted equations are based on a la rge data set and therefore provide a useful basis for future work on d rying and storage of rapeseed. (C) 1998 Silsoe Research Institute.