采用隧道式微波干燥设备对疏浚底泥进行了连续化微波干燥实验,系统研究了微波功率与进料量对疏浚底泥微波干燥特性的影响,建立了干燥所需时间与微波功率、进料量之间的数学模型。结果表明,疏浚底泥在连续化微波干燥过程中经历了加速干...采用隧道式微波干燥设备对疏浚底泥进行了连续化微波干燥实验,系统研究了微波功率与进料量对疏浚底泥微波干燥特性的影响,建立了干燥所需时间与微波功率、进料量之间的数学模型。结果表明,疏浚底泥在连续化微波干燥过程中经历了加速干燥、恒速干燥和降速干燥3个阶段;微波功率越大,进料量越小,干燥所需时间明显缩短,水分比下降的速率加快;微波功率对低含水率底泥干燥过程中水分比影响较大,对干燥速率影响不明显。在同一进料量时,随着功率的增大,干燥所需时间呈指数衰减形式增加,能耗逐渐降低;在同一功率下,干燥所需时间与进料量呈正比,能耗逐渐增大。底泥进料量在1.28～5.12 kg/min之间,以微波功率3 k W进行干燥为宜,既达到干燥的目的,又能节省能耗。展开更多
In this research, convective and microwave drying characteristics, energy requirement and color changes of dill leaves （Anethum graveolens L.） were reported. Dill leaves were dehydrated in a computer connected paral...In this research, convective and microwave drying characteristics, energy requirement and color changes of dill leaves （Anethum graveolens L.） were reported. Dill leaves were dehydrated in a computer connected parallel air flow type dryer and in a microwave oven dryer. Samples of freshly harvested dill leaves were dehydrated under three air temperatures of 50, 60 and 70 ℃, and at three microwave power levels of PL-1 （90 W）, PL-2 （160 W） and PL-3 （350 W）. Selected drying air velocity was 0.30 m/s for all temperatures. Dill leaves were dehydrated from the initial moisture content of 735 （percentage dry basis） to a final moisture content of 8%-10%. During convective drying experiment, products were weighted automatically by the balance per 5-10 min. Data were transferred to the computer and processed by software. During microwave drying, the products were weighted, and data were recorded manually per 15-60 min. The influence of drying method, drying air temperature and microwave power level has also been studied. Hunter L, a, b values system was also used to evaluate changes in total color difference （AE） on dried products. The results showed that convective drying air temperature and microwave oven power levels influenced the total drying time, total energy requirement, specific energy requirement and color difference for dill leaves. The minimum specific energy requirement was determined as 10.72 kWh/kg and 18.72 kWh/kg for 70 ℃ and PL-3, respectively. 70℃ drying air temperature and PL-3 were found to yield better quality product in terms of color retention of Hunter L, a, b and AE. As a result, to reduce drying energy consumption and to keep better color retention, convective drying can be recommended for this application.展开更多
文摘采用隧道式微波干燥设备对疏浚底泥进行了连续化微波干燥实验,系统研究了微波功率与进料量对疏浚底泥微波干燥特性的影响,建立了干燥所需时间与微波功率、进料量之间的数学模型。结果表明,疏浚底泥在连续化微波干燥过程中经历了加速干燥、恒速干燥和降速干燥3个阶段;微波功率越大,进料量越小,干燥所需时间明显缩短,水分比下降的速率加快;微波功率对低含水率底泥干燥过程中水分比影响较大,对干燥速率影响不明显。在同一进料量时,随着功率的增大,干燥所需时间呈指数衰减形式增加,能耗逐渐降低;在同一功率下,干燥所需时间与进料量呈正比,能耗逐渐增大。底泥进料量在1.28～5.12 kg/min之间,以微波功率3 k W进行干燥为宜,既达到干燥的目的,又能节省能耗。
文摘In this research, convective and microwave drying characteristics, energy requirement and color changes of dill leaves （Anethum graveolens L.） were reported. Dill leaves were dehydrated in a computer connected parallel air flow type dryer and in a microwave oven dryer. Samples of freshly harvested dill leaves were dehydrated under three air temperatures of 50, 60 and 70 ℃, and at three microwave power levels of PL-1 （90 W）, PL-2 （160 W） and PL-3 （350 W）. Selected drying air velocity was 0.30 m/s for all temperatures. Dill leaves were dehydrated from the initial moisture content of 735 （percentage dry basis） to a final moisture content of 8%-10%. During convective drying experiment, products were weighted automatically by the balance per 5-10 min. Data were transferred to the computer and processed by software. During microwave drying, the products were weighted, and data were recorded manually per 15-60 min. The influence of drying method, drying air temperature and microwave power level has also been studied. Hunter L, a, b values system was also used to evaluate changes in total color difference （AE） on dried products. The results showed that convective drying air temperature and microwave oven power levels influenced the total drying time, total energy requirement, specific energy requirement and color difference for dill leaves. The minimum specific energy requirement was determined as 10.72 kWh/kg and 18.72 kWh/kg for 70 ℃ and PL-3, respectively. 70℃ drying air temperature and PL-3 were found to yield better quality product in terms of color retention of Hunter L, a, b and AE. As a result, to reduce drying energy consumption and to keep better color retention, convective drying can be recommended for this application.
