黑皮冬瓜分段式变温热泵干燥工艺研究

Study on Segmented Variable Temperature Drying Technology by Heat Pump of Black Wax Gourd

为提升黑皮冬瓜干燥品质及降低干燥能耗,对黑皮冬瓜分段式变温热泵干燥工艺进行了研究。通过研究湿度对冬瓜干燥过程、瓜干品质及干燥能耗的影响,确定了最适相对湿度为40%和50%。根据最适湿度条件下干燥前期温度的波动情况设计了4种分段式变温干燥工艺,采用综合加权评分法对4种工艺进行比较,得到了最适分段式变温热泵干燥工艺为:温度50℃(5 h)-60℃(至结束),相对湿度50%,循环风速1.5 m/s,瓜片厚度6 mm。将热泵干燥方式与传统的电热干燥方式进行比较,发现热泵干制的瓜干品质显著优于电热干制的瓜干(P<0.05),热泵恒温干燥较电热恒温干燥节能38.93%,热泵变温干燥可在进一步提升瓜干品质的同时较热泵恒温干燥节能11.25%。

In order to improve the quality of dried wax gourd and reduce the energy consumption of drying process,the segmented variable temperature drying technology by heat pump of wax gourd was studied.The effects of humidity on the drying process,quality of dried wax gourd and energy consumption of drying process were investigated,and the optimal relative humidity was confirmed as 40%and 50%.According to the fluctuation of temperature at the early stage of drying process under the optimal humidity condition,four variable-temperature drying processes were designed and compared by comprehensive weighted score method,then the optimal variable-temperature drying technique by heat pump was determined as follows:temperature 50℃(for 5 h)-60℃(the end),relative humidity 50%,circulation air speed 1.5 m/s,and slice thickness 6 mm.Comparing with the traditional electro-thermal drying mode,the quality of the black wax gourd slice dried by heat pump drying was significantly better than electro-thermal drying(P<0.05),and the energy consumption by heat pump constant temperature drying was saved by 38.93%.While heat pump variable temperature drying not only improved the quality of the dried wax gourd,but also reduced energy consumption by 11.25%compared with heat pump constant temperature drying.