CAJ | 학술논문

为了揭示干燥过程中荔枝果体内部温度和水分分布的动态特征，指导干燥工艺设计，提高干燥品质，降低干燥能耗。基于扩散模型，试验考察荔枝果体的干燥特征参数，测试结果显示：在相对湿度10%、温度35℃～50℃范围内，荔枝果体的干燥常数为0.5965～0.6717 h-1，干基平衡含水率在7.55%～60.92%之间；而在相对湿度60%、温度40℃和50℃条件下，荔枝果体的干燥常数分别为0.076和0.098h-1，干基平衡含水率分别为211.35%和141.06%，表明了荔枝的干燥特征参数受干燥条件的影响很大；干燥过程中，果体内部的水蒸气分压力存在最大极值点，在极值点之后的干燥接近于等温变化过程。基于拉氏变换，联立求解了导热基础方程和干燥热平衡方程，得到了荔枝在非稳态干燥过程中果体内部温度和水蒸气分压力分布的解析式。利用初始温度10℃、干基含水率为388%的荔枝果，在干燥温度50℃，相对湿度10%的干燥条件下进行验证试验的结果表明，解析值与试验值比较一致，证实了模型解析预测荔枝非稳态干燥热湿特性的有效性。研究成果充实了荔枝干燥热质传递解析理论，对指导干燥工艺设计，实现节能干燥具有重要现实意义。
위료게시간조과정중려지과체내부온도화수분분포적동태특정，지도간조공예설계，제고간조품질，강저간조능모。기우확산모형，시험고찰려지과체적간조특정삼수，측시결과현시：재상대습도10%、온도35℃～50℃범위내，려지과체적간조상수위0.5965～0.6717 h-1，간기평형함수솔재7.55%～60.92%지간；이재상대습도60%、온도40℃화50℃조건하，려지과체적간조상수분별위0.076화0.098h-1，간기평형함수솔분별위211.35%화141.06%，표명료려지적간조특정삼수수간조조건적영향흔대；간조과정중，과체내부적수증기분압력존재최대겁치점，재겁치점지후적간조접근우등온변화과정。기우랍씨변환，련립구해료도열기출방정화간조열평형방정，득도료려지재비은태간조과정중과체내부온도화수증기분압력분포적해석식。이용초시온도10℃、간기함수솔위388%적려지과，재간조온도50℃，상대습도10%적간조조건하진행험증시험적결과표명，해석치여시험치비교일치，증실료모형해석예측려지비은태간조열습특성적유효성。연구성과충실료려지간조열질전체해석이론，대지도간조공예설계，실현절능간조구유중요현실의의。
The dynamic characteristics of temperature and moisture distribution within litchi, which is the key influence on drying quality formation and energy-consumption, is the important technical foundation problem for litchi postpartum processing. In order to reveal the dynamic characteristics of temperature and moisture distribution within litchi in unsteady drying process, guide the drying process design, improve the drying quality, and reduce drying energy, based on the diffusion model, the characteristic parameter of litchi is studied. Meanwhile, the drying characteristics representation of litchi is investigated on the basis of the drying characteristics test on litchi peel, pulp, and kernel. When the relative humidity is 10 percent and temperatures range from 35℃ to 50℃, the drying constant and dry basis equilibrium moisture content is researched, and the results are 0.5965 h-1-0.6717 h-1 and 7.55 percent-60.92 percent, respectively. While the relative humidity is 60 percent, and the temperature is 40℃ and 50℃, the researchers have determined that the drying constant is 0.076 h-1 and 0.098 h-1, respectively, and that the dry basis equilibrium moisture contents is 211.35 percent and 141.06 percent, respectively. The results show that the drying conditions have great influence on the drying characteristic parameters of litchi. The water vapor pressure inside litchi exists at an extreme value point during litchi drying, and after that, the drying process is closed to isothermal processes. At the beginning of litchi drying (within 20 min), the internal temperature difference of litchi is the greatest. The thermal conductivity coefficients of peel, pulp, and kernel have some differences, but in the same drying time, they have less effect on the internal temperature distribution of litchi. By using the Lars transformation, the heat conductivity and thermal balance equations are solved simultaneously, and the internal temperature, water vapor partial pressure distribution and its analytic formula of variation law of litchi are achieved. The validation test is investigated when the drying medium temperature is 50 ℃, the relative humidity is 10 percent, the litchi initial temperature is 10 ℃, and the dry basis moisture content is 388 percent. The results show that the measured values of the internal temperature change of litchi is consistent with the analytical values, which confirm the reliability of the analytical model. The research results are of great significance for providing reference to reveal the drying quality mechanism of litchi, enriching analytical theory of the litchi drying thermal and mass transfer, as well as improving the drying quality of litchi, guiding drying design, achieving high efficiency, and saving energy.