真空脉动干燥设备设计及对南瓜片干燥影响的研究

Design of Pulsating Vacuum Drying Equipment and Its Effects on the Drying Characteristics of Pumpkin Slices

针对常压干燥效率低、真空干燥能耗大等问题，设计真空脉动干燥设备并应用于南瓜片的干燥。该设备主要由干燥室、加热系统、真空系统和控制系统组成，南瓜片放置在干燥室内的加热板上，干燥室内的压力由控制系统改变卸压阀和抽空阀地开闭来实现，抽真空的同时，设备还能将一部分的水蒸气吸走，完成干燥过程。研究了不同常压保持时间（3min、5min、7min、9min、11min和13rain）、不同真空保持时间（5min、10min、15min、20min和25min）、不同干燥温度（50℃、55℃、60℃和65oC）以及不同切片厚度（5min、7mn3、9mm和11mIn）对干燥过程及品质的影响。综合干燥室内真空度与南瓜片内部温度之间的关系、干燥效率与能耗问题，得到较优的工作参数：常压保持时间9min，真空保持时间10rain，干燥温度60℃，切片厚度7mn3，为南瓜片以及其它物料的干燥提供了理论研究基础。

Aiming at the problem of low drying efficiency and the vacuum drying energy consumption, the vacuum pulsating drying equipment was designed and applied to the drying of pumpkin slices. This drying equipment was comprised of the drying chamber, heating system, vacuum system and control system. The pumpkin slices were placed on the surface of the heating panel in the drying chamber. The pressure in the drying chamber was controlled by the control system to change the pressure relief valve and the evacuation valve to open and close. When the drying chamber was vacuumized, some vapor could also be pumped out to complete the drying process. The effects of different atmospheric pressure durations （3 min, 5 min, 7 min, 9 min, 11 min, 13 min）, vacuum durations （5 min, 10 min, 15 min, 20 min, 25 min）, drying temperatures （50℃, 55℃, 60℃, 65℃） and thickness （5 mm, 7 mm, 9 mrn, 11 mm） on the drying process of pumpkin slices were studied. According to the relationship between the vacuum pressure of the drying chamber and the internal temperature of the pumpkin slices as well as the relationship between the drying efficiency and the energy consumption, the optimum parameters of pumpkin slices treated by pulsating vacuum drying were as follows： atmospheric pressure duration 9 min, vacuum duration 10 min, drying temperature 60℃ and thickness 7 ram.