Infrared heaters for vacuum drying under the pressure close to the one of the triple point of water

When using infrared drying lamps, one of the disadvantages is the uneven heating of the product over the surface of the trays. The uneven heating of the surface is due to the geometric properties of the radiation source. The work is devoted to the modernization of the heat supply system in infrared drying plants. The object of the study was a vacuum drying unit with a cylindrical chamber. To carry out the research, a software was used to simulate an optical heat supply system using various reflectors. The behavior of the rays and their distribution over the surface of the tray with the product is analyzed. The efficiency of using a parabolic research on drying black currant berries with the use of a designed reflector and without it has been carried out. During the experiments, the heating time of the product was established at various points in the tray. Without a reflector, the time for heating a berry in the center to a given temperature was 41 minutes in the center and 66 minutes in the periphery. Installing the reflector provides more uniform heating over the entire surface of the tray. The difference between the heating time in the center and at the periphery of the tray was no more than 15 %, while in the absence of a reflector this value was 60 %. In addition, the total warm-up time was reduced by increasing the heat flux density due to the installation of a reflector. We also measured the mass fraction of moisture in dry berries at various points in the tray. The results indicate that without a reflector, there is some difference in the mass fraction of moisture in dry berries along the width of the tray. Installing a reflector significantly reduces this difference.