The Development Of Infrared Assisted Freeze-Drying Apparatus

Vacuum freeze-drying plays an irreplaceable role for drying products being of excellent quality, complete dehydration and light quality, however, its disadvantages restrict the further development, such as slow drying speed and more energy consumption. To deal with the problem, the paper developed a set of infrared auxiliary freeze drying device to improve the drying rate of freeze-drying. The device was modified from freeze drying machine and added infrared auxiliary freeze drying unit, at the same time, a set of automatic control system was developed in order to improve the freeze drying rate and achieve a high precision automatic control during the freeze-drying experiment process.Some hardwires were added to the device, heater parts such as infrared lamp, silicone heating plate, control components were comprised of data acquisition card, SCR voltage regulator module, temperature control instruments, relays etc. The process control system can be achieved many functions being online measurement, recording the temperature and quality of the material, changing the freezing temperature of the drying chamber, controlling the heating power of infrared lamps and adjusting the heating temperature of the heating plate, which consist of data acquisition system, the feedback control system, SCR regulator systems, instrument temperature control system.The PC software was the development platform of labvIEW2010 which was communicated with the next crew by using VISA node, can has some operating functions, for example receiving measurement data and drawing the curve, data preservation and querying historical data, the settings of heating temperature and time of the heater, switch of compressor and vacuum pump.In this paper, the experimental platform was the above device, researched the process of infrared freeze-drying potato, which the shelf heating temperature was 30℃ and the infrared heating power was 100W, the results showed that the infrared assisted freeze drying can increasing the drying rate and shorten the drying time.