雪莲果热泵干燥特性及品质研究(英文)

D rying Characteristics and Quality of Yacon(Smallanthus sonchifolius) during Heat Pump Drying

研究雪莲果样品厚度、装料量、干燥温度、风速和旁通比对雪莲果热泵干燥特性及质量变化的影响。结果表明：雪莲果干燥速率随着样品厚度和装料量的增加而降低,随着干燥温度和风速的升高而增加。雪莲果热泵干燥过程绝大部分以降速干燥为主伴随相对较短时间的恒速干燥,而有些干燥速率曲线只存在降速干燥阶段。综合考虑单位能耗除湿率、色泽差异、收缩率、复水比,雪莲果热泵干燥最适参数范围：样品厚度2~4 mm、装料量1~2 kg/m2、干燥温度25~35℃、风速1.5~2.0 m/s。而旁通比对雪莲果热泵干燥进程影响不显著。

The effects of sample thickness, surface load, drying temperature, air velocity and evaporator bypass air ratio（BAR） on the drying characteristics and quality of yacon during heat pump drying（HPD） were investigated. Experimental results showed that higher thickness and surface load resulted in lower drying rate（DR）. DR increased with increasing drying temperature and air velocity. Most DR curves displayed both long time falling rate period and relatively short time constant rate period while only falling rate period existed in some DR curves. Thickness of 2-4 mm, surface load of 1-2 kg/m2, drying temperature of 25-35 ℃ and air velocity of 1.5-2.0 m/s were preferred by considering specific moisture evaporation rate（SMER）, total color difference（ΔE）, shrinkage ratio（S R） and rehydration ratio（R R）. However, BAR had little influence on the HPD process of yacon.