真空微波干燥胡萝卜的恒速干燥速度及临界含水量的实验和回归模型

Test and regression model on critical moisture content of carrot and drying rate during the stage of constant rate by vacuum microwave drying

为探索出不同真空微波干燥条件对胡萝卜恒速干燥速度和临界含水量的影响,选取微波功率Q、负载量M、切片厚度δ等因素,范围分别在300～500W、80～140g、4～8mm,以临界含水量和恒速干燥速度为目标在0·08MPa真空条件下进行实验。实验结果表明:随着微波功率从300W增加到500W时,恒速干燥速度提高了87·5%;随着负载量从80g增加到140g时,恒速干燥速度降低了50%;随着切片厚度从4mm增加到8mm时,恒速干燥速度提高了81·3%。临界含水量仅与负载量显著相关,随着负载量从80g增加到140g时,临界水分含量从5·4kg/kg降低到2·2kg/kg。根据实验数据,采用线性回归的方法,得到恒速干燥速度U及临界含水量Xc的数学模型为:U=45·558+0·346Q-1·431M+17·636δ;Xc=14·962-0·080M-0·400δ。

To explore different microwave vacuum drying conditions on critical moisture content of carrot and drying rate during the stage of constant rate,the critical water content and the time to reach this point were taken as the criterion, the microwave power （ 300- 500W）, loading （ 80- 140g ）, slice thickness （ 4 - 8mm ） in the conditions of 0.08MPa vacuum,the drying experiments were tested respectively.The result showed,the microwave power from 300W to 500W, constant drying rate increased 87.5% ; the loading from 80g to 140g, the constant drying rate decreased by 50%;the slice thickness from 4mm to 8mm, constant drying rate increased 81.3%. The critical moisture content was only affected significant by loading,the loading from 80g to 140g,the critical moisture content from 5.4kg/kg down to 2.2kg/kg.According to the experimental data, using linear regression method ,the constant drying rate and critical moisture content mathematical models were obtained： U = 45.558 ＋ 0.346Q- 1.431M ＋ 17.636δ, Xc = 14.962-0.080M-0.400δ