采用一个多项式方程拟合粮食水分吸着等温线

摘要

The paper has presumed that the Equilibrium Moisture Content (EMC)of grain was both the polyno-mial function of relative humidity (RH)and the linear function of temperature.Here an EMC /ERH model has been developed with C1 ~C7 as parameters.The model was used to fit the measured EMC /ERH data of the Chinese varie-ties including 17 rough rice,11 milled rice,14 wheat,16 shelled corn,and 10 soybean which have a determination coefficients above 0.994,mean relative error (MRE)<3.46%,better than the commonly cited models such as Modified -Chung -Pfost (MCPE),Modified -Halsey (MHAE),Modified -Henderson (MHE),Modified -Guggenheim -Anderson -deBoer (MGAB)and Modified -Oswin (MOE).In comparison of the isotherms derived from the polynomial model,there were apparent hysteresis between desorption and adsorption for cereal grains,while no significant hysteresis for soybean.The relatively safe storage moisture content derived from the developed desorp-tion polynomial equation at 30 ℃ was below 14% for cereal grain and 11.47% for soybean.%假定粮食平衡水分（EMC）是相对湿度（RH）的多项式函数，也是温度（t）的线性函数，提出了一个方程 EMC ＝C1 RH3＋C2 RH2＋C3 RH ＋C4 RH2 t ＋C5 RHt ＋C6 t ＋C7，C1～C7是方程参数。此方程对我国主要粮种水分吸着等温线的拟合度指标决定系数 R2＞0．994，平均相对误差 MRE％＜3．46，这些指标优于修正 Chung －Pfost （MCPE）、修正 Halsey （MHAE）、修正 Henderson （MHE）、修正 Guggenheim －Anderson －deBoer （MGAB）及修正Oswin （MOE）的拟合度指标。分析该方程拟合出的粮食吸着等温线，谷物解吸与吸附之间存在明显的滞后现象，而大豆滞后现象不明显。由拟合的解吸等温线分析30℃相对安全水分值，谷物低于14％，大豆为11．47％。