农业工程学报
農業工程學報
농업공정학보
2015年
5期
317-324
,共8页
张卫鹏%高振江%肖红伟%郑志安%巨浩羽%谢龙
張衛鵬%高振江%肖紅偉%鄭誌安%巨浩羽%謝龍
장위붕%고진강%초홍위%정지안%거호우%사룡
干燥%模型%温度%茯苓%Weibull函数%评价
榦燥%模型%溫度%茯苓%Weibull函數%評價
간조%모형%온도%복령%Weibull함수%평개
drying%models%temperature%poria cocos%Weibull function%evaluation
为缩短干燥时间，克服茯苓块干燥后表面龟裂、易于破碎的缺陷，改善干燥品质；将自然晾晒、普通热风干燥、气体射流冲击干燥、真空脉动干燥4种技术应用于茯苓块的干燥，研究了茯苓的干燥特性；利用Weibull函数对其干燥曲线进行拟合并分析干燥过程，结合尺度参数、形状参数计算茯苓块的水分有效扩散系数、干燥活化能，并与Fick第二定律进行比较；测定了不同干燥条件下的破碎率、浸出物质量分数；并基于能耗、尺度参数、破碎率、浸出物质量分数对3种人工干燥方式进行了综合评价。结果表明：1）茯苓块在4种干燥方式下均表现为降速干燥，但普通热风干燥、真空脉动干燥前期存在升速段；2）Weibull 函数能够准确拟合不同干燥方式下的干燥曲线；尺度参数随着温度、风速的增加而减小；形状参数与干燥方式有关，普通热风、真空干燥的形状参数值均大于1，气体射流干燥的形状参数值均小于1；3）基于Weibull函数计算水分有效扩散系数、干燥活化能，可克服Fick第二定律只适用于降速干燥的缺陷；估算的水分扩散系数范围为3.90×10-9～20.40×10-9m2/s；干燥活化能为29.45～40.09 kJ/mol，且不同干燥方式间的活化能存在差异；4）不同干燥方式下茯苓块破碎率存在显著性差异（p<0.05）；真空脉动与自然晾晒的破碎率均低于5.00%；试验参数范围内，气体射流的温度、风速与破碎率无相关关系，破碎率均值为62.68%；普通热风干燥方式下，破碎率随温度的升高而增大；5）真空脉动干燥方式下浸出物质量分数最高，为4.54%～4.75%；综合评价结果表明茯苓块的干燥宜采用真空脉动干燥技术。该研究探索了不同干燥技术下茯苓块的干燥特性和品质，为选择合适的干燥工艺提供了理论依据。
為縮短榦燥時間，剋服茯苓塊榦燥後錶麵龜裂、易于破碎的缺陷，改善榦燥品質；將自然晾曬、普通熱風榦燥、氣體射流遲擊榦燥、真空脈動榦燥4種技術應用于茯苓塊的榦燥，研究瞭茯苓的榦燥特性；利用Weibull函數對其榦燥麯線進行擬閤併分析榦燥過程，結閤呎度參數、形狀參數計算茯苓塊的水分有效擴散繫數、榦燥活化能，併與Fick第二定律進行比較；測定瞭不同榦燥條件下的破碎率、浸齣物質量分數；併基于能耗、呎度參數、破碎率、浸齣物質量分數對3種人工榦燥方式進行瞭綜閤評價。結果錶明：1）茯苓塊在4種榦燥方式下均錶現為降速榦燥，但普通熱風榦燥、真空脈動榦燥前期存在升速段；2）Weibull 函數能夠準確擬閤不同榦燥方式下的榦燥麯線；呎度參數隨著溫度、風速的增加而減小；形狀參數與榦燥方式有關，普通熱風、真空榦燥的形狀參數值均大于1，氣體射流榦燥的形狀參數值均小于1；3）基于Weibull函數計算水分有效擴散繫數、榦燥活化能，可剋服Fick第二定律隻適用于降速榦燥的缺陷；估算的水分擴散繫數範圍為3.90×10-9～20.40×10-9m2/s；榦燥活化能為29.45～40.09 kJ/mol，且不同榦燥方式間的活化能存在差異；4）不同榦燥方式下茯苓塊破碎率存在顯著性差異（p<0.05）；真空脈動與自然晾曬的破碎率均低于5.00%；試驗參數範圍內，氣體射流的溫度、風速與破碎率無相關關繫，破碎率均值為62.68%；普通熱風榦燥方式下，破碎率隨溫度的升高而增大；5）真空脈動榦燥方式下浸齣物質量分數最高，為4.54%～4.75%；綜閤評價結果錶明茯苓塊的榦燥宜採用真空脈動榦燥技術。該研究探索瞭不同榦燥技術下茯苓塊的榦燥特性和品質，為選擇閤適的榦燥工藝提供瞭理論依據。
위축단간조시간，극복복령괴간조후표면구렬、역우파쇄적결함，개선간조품질；장자연량쇄、보통열풍간조、기체사류충격간조、진공맥동간조4충기술응용우복령괴적간조，연구료복령적간조특성；이용Weibull함수대기간조곡선진행의합병분석간조과정，결합척도삼수、형상삼수계산복령괴적수분유효확산계수、간조활화능，병여Fick제이정률진행비교；측정료불동간조조건하적파쇄솔、침출물질량분수；병기우능모、척도삼수、파쇄솔、침출물질량분수대3충인공간조방식진행료종합평개。결과표명：1）복령괴재4충간조방식하균표현위강속간조，단보통열풍간조、진공맥동간조전기존재승속단；2）Weibull 함수능구준학의합불동간조방식하적간조곡선；척도삼수수착온도、풍속적증가이감소；형상삼수여간조방식유관，보통열풍、진공간조적형상삼수치균대우1，기체사류간조적형상삼수치균소우1；3）기우Weibull함수계산수분유효확산계수、간조활화능，가극복Fick제이정률지괄용우강속간조적결함；고산적수분확산계수범위위3.90×10-9～20.40×10-9m2/s；간조활화능위29.45～40.09 kJ/mol，차불동간조방식간적활화능존재차이；4）불동간조방식하복령괴파쇄솔존재현저성차이（p<0.05）；진공맥동여자연량쇄적파쇄솔균저우5.00%；시험삼수범위내，기체사류적온도、풍속여파쇄솔무상관관계，파쇄솔균치위62.68%；보통열풍간조방식하，파쇄솔수온도적승고이증대；5）진공맥동간조방식하침출물질량분수최고，위4.54%～4.75%；종합평개결과표명복령괴적간조의채용진공맥동간조기술。해연구탐색료불동간조기술하복령괴적간조특성화품질，위선택합괄적간조공예제공료이론의거。
Poria cocos is a traditional Chinese herbal medicine. It generally takes almost 7 days to be dried by traditional natural drying, and it is sensitive to microbial spoilage during drying. Poria cocos blocks (15 mm×15 mm×15 mm) are easily broken at the traditional hot air drying, such as oven drying. There are many drying methods, but we don’t know how to choose the method quickly. The knowledge of different drying mechanism is necessary for heat and moisture transportation, energy savings and quality of product. To study the drying characteristics of poria cocos, overcom the drawbacks of poria cocos blocks which is easily broken and surface cracking after drying, improve the quality of dried poria cocos and shorten its drying time, the nature drying, oven drying ,air impingement drying, pulsed vacuum drying approaches were applied to poria cocos drying. The Weibull distribution model was applied to the drying process under different drying methods and the results were analyzed. Combined with the GB-4857.5 T–1992《Droping test method》and《Pharmacopoeia of People’s Republic of China》, the broken rate and extractum of poria cocos at different drying conditions were tested. The moisture effective diffusivity velocity and the activation energy were also calculated based on the scale parameter and shape parameter, and compared with Fick’s second law. A comprehensive evaluation was also carried out for kinds of artificial drying methods based on the utilization rate of energy consumption, scale parameter, broken rate, extractum. The main results are as following: 1)four drying methods drying process all occurred in the falling rate period without constant speed stage, but oven drying and pulsed vacuum drying had the up-stage at the starting; 2) Weibull function can fit the drying curve of different methods accurately. Scale parameter decreased with the increasing temperature and air velocities. The shape parameter was related to the drying method, the shape parameter of oven drying and vacuum drying was higher than 1,and the air impingement drying’s shape parameter was lower than 1; 3) the moisture effective diffusivity velocity and the activation energy were calculated based on the Weibull function, it can overcome the defects that the Fick's second law only was applied to the falling rate drying; The moisture effective diffusivity of poria cocos was 3.90×10-9-20.40×10-9 m2/s; the activation energy was 29.45-40.09 kJ/mol, but there were differences among different drying methods; 4) the broken rate of poria cocos blocks exhibited significant difference for different drying methods, the broken rate of nature drying and vacuum drying was lower than 5.00%; At the range of testing parameters, temperature and air velocities didn’t have significantly impact on the broken rate, The average was 62.68%; The broken rate increased with the rising temperature at oven drying; and 5) the extractum of poria cocos dried by pulsed vacuum method was most than others, and it ranged from 4.54% to 4.75%. Comprehensive evaluation results showed that the best drying method is pulsed vacuum drying. The results provide a reference for the application of Weibull distribution on poria cocos drying and help people gain the best drying method.
