热泵-转轮联合除湿对胡萝卜片的干燥特性分析

Analysis of Drying Characteristics of Carrot Slices by Heat Pump-Rotary Dehumidification Equipment

为实现农产品节能和提升干燥品质,采用新型热泵-转轮联合除湿实验设备,对温度35~45℃、干燥风速1~3 m/s、切片厚度3~7 mm条件下胡萝卜的干燥特性进行了研究。结果表明:随着干燥温度的上升,45℃工况下最大干燥速率相较于40℃和35℃分别提升了18.1%和60.9%,干燥时长分别缩短了1.5 h和2.5 h;当提高干燥风速时,样品达到平衡的时间随之缩短,每提升1 m/s的风速,干燥时长缩短0.5 h;在切片厚度为3 mm时,干燥速率最大值可达5.88 g/(g·h),较5 mm和7 mm厚度下干燥速率分别提升42.7%和116.2%,干燥时长分别缩短2 h和4 h。此外,同一工况下,文章所提出的干燥系统相较于单一热泵最大干燥速率提升了23.4%,复水率提升了54.9%,有效水分子扩散系数约为单一热泵的1.18倍,干燥时长缩短了0.5 h,干燥完成后的胡萝卜片样品具有更好的延展性和色泽均匀度,且相较于单一热泵干燥的单位能耗降低了39.46%。新型热泵-转轮联合除湿装备具有良好的干燥特性和节能性。

In order to achieve energy conservation and improve drying quality of agricultural products,a new type of heat pump rotary combined dehumidification experimental equipment was used to study the drying characteristics of carrots under conditions of temperature 35-45℃,drying wind speed 1-3 m/s,and slice thickness 3-7 mm.The results showed that with the increase of drying temperature,the maximum drying rate under 45℃increased by 18.1%and 60.9%compared with 40℃and 35℃,and the drying time was shortened by 1.5 h and 2.5 h,respectively;when the drying air speed was increased,the time for the sample to reach equilibrium was shortened,and the drying time was shortened by 0.5 h for every 1 m/s increase in wind speed;and the maximum drying rate could reach 5.88 g/(g·h)when the slice thickness was 3 mm.Compared with 5 mm and 7 mm thickness,the drying rate is increased by 42.7%and 116.2%,respectively,and the drying time is shortened by 2 h and 4 h,respectively.In addition,under the same working conditions,compared with a single heat pump,the maximum drying rate of the drying system proposed in this paper is increased by 23.4%,the rehydration rate is increased by 54.9%,the effective water molecular diffusion coefficient is about 1.18 times that of a single heat pump,the drying time is shortened by 0.5 h,the carrot slice sample after drying has better ductility and color uniformity,and the unit energy consumption is reduced by 39.46%compared with the single heat pump drying.The new heat pump-runner combined dehumidification equipment has good drying characteristics and energy saving.