DRYING PRODUCTS WITH INFRARED RAYS

ABSTRACT

By maximizing the nutritional value and taste of products, the use of infrared rays during drying increases the heat density on the product surface, and the intensity of the process can be increased to a certain extent due to the fact that shortwave IR rays penetrate deeper into the material.

АННОТАЦИЯ

Максимально повышая пищевую ценность и вкусовые качества продуктов, использование ИК-лучей при сушке увеличивает плотность тепла на поверхности продукта, а интенсивность процесса можно в определенной степени увеличить за счет того, что коротковолновые ИК-лучи проникают глубже в материал.

Keywords: IR-rays, range, intensity, vibration, electromagnetic, thermoradiation, combination, absorption.

Ключевые слова: ИК-лучи, диапазон, интенсивность, вибрация, электромагнитное, термоизлучение, сочетание, поглощение.

Research in recent years has focused on improving drying methods that maximize the nutritional value and taste of products, as well as ensuring high process efficiency.

Infrared drying, its types and possibilities of application by combining heat carriers. By using infrared rays in the drying of products, the heat density reaching the surface of the product increases and the intensity of the process can be increased to a certain extent due to the fact that short-wave IR rays penetrate deeper into the material.

Infrared rays include rays with wavelengths ranging from 0.77 to 340 μm. In practice, rays with a wavelength of 0.77 to 5-6 microns are used for drying. IR-irradiation of thick material results in a certain temperature change (compared to normal convective drying). Also, the flow of moisture into the material brings with it a certain amount of heat, which accelerates the internal heat exchange. To increase the intensity of thermoradiation drying, IR rays are required to penetrate the material as deeply as possible. It depends on the conductivity of the material and the wavelength of the IR rays. The lower it is, the greater the penetration capacity of infrared rays. As the layer thickness decreases and the moisture content in the material decreases, the permeability of the products increases.

Processing of agricultural products in the electromagnetic field in the IR-RAN range is a combination of heat transfer, in which infrared rays are converted into thermal energy without direct interaction between the energy source and the product, with energy transfer as electromagnetic oscillations entering the product. Infrared rays have the ability to penetrate the product to a certain depth and affect the molecular structure of the material, which ensures a rapid rise in temperature inside the product. Infrared drying is based on the absorption of infrared rays of a certain wavelength by the moisture in the product.

The boiling point of water depends on the total pressure, the lower the pressure, the lower the boiling point. Loss of moisture at low temperatures allows complete preservation of almost all proteins and amino acids, carbohydrates, biologically active substances, vitamins, minerals, dyes and odors. Vacuum drying is the most optimal method.

Despite the intensive (rapid) heating of the surface layer during the initial period of the infrared method of energy transfer, no significant moisture loss from the product is observed. In this case, the moisture is redistributed along the thickness of the layer. In the case of thermal moisture permeability, the transition of the bulk of the moisture to the vapor phase and the transfer of a small amount of moisture into the layer leads to dehydration of the surface layer. These studies have shown that the duration of IR-drying is 1.5-2 times shorter than other methods.

In order to intensify the drying process and maintain the high quality of the finished product, it is necessary to determine the physicochemical, structural-mechanical, thermoradiation and heat-physical properties of the product, as well as the basic laws of heat treatment.

Processing in the electromagnetic field in the IR range corresponds to a wavelength of 0.76-750 μm, which is conventionally divided into three smaller ranges: long-wave - 750-25 μm, medium-wave - 25-2.5, short-wave - 2.5-0.76 μm. The range of IR radiation is represented by three directions: wavelength - short infrared range (NIR) to 0.75-1.4 μm; average - up to 1.4-3 microns (MIR) and long infrared range - up to 3-1000 microns (FIR).

Water and organic components, especially protein and starch, absorb energy over a long range (wavelength 2.5mkm), while many foods have low absorption properties of wavelengths smaller than 2.5mkm. In IR heating, short waves are absorbed by water, while long waves are absorbed by the surface of the product. This means that it is more efficient to dry products of minimum thickness on long-range waves (25-100mkm), while it is more efficient to dry thick pieces on short-range waves (0.75-3.0).

In studying the mechanism of action of IR rays on food, they are described as a matrix of various biological polymers, salts, water. Each element in the food system absorbs IR rays of a certain wavelength. Proteins range from 6 to 9 microns cha absorbs waves in the range of cha, lipids absorb almost all waves in the range of 0.25 to 10 μm, but absorption peaks occur in the range of 3-4 μm, 6 μm and 6-9 μm, shaker absorbs waves in the range of 7-10 μm and 0.5-4 μm . The maximum absorption of water is 2 μm and the minimum absorption is 6 μm at wavelength.

The use of IR-heating in the drying of thin layers is very effective, as the drying intensity increases by 1.5-2 times, energy consumption is reduced by 1.5 times.

List of references:

1. Douglas J. Arent, Alison Wise, Rachel Gelman. The status and prospects of renewable energy for combating global warming // Energy Economics, Volume 33, Issue 4, July 2011, Pages 584-593.
2. Bahrus D. Solar drian drying // Crops and soils. -№4 (30). - P.14-15.
3. Lowand T.A. Solar catined drues // Solar energy. - №4. -P.32-36.
4. Niles P.W., Carnegie E.J., Pohl J.G., Cherne J.M. Design and performance of an aircollector for indusrial croop dehydration // Solar energy. - №1 (20). -P.19-23.
5. Norkulova K.T., Iskandarov Z.S., Jumaev B.M. Issledovanie kombinirovannoy sushilnoy ustanovki. International Scientific Conference Innovation Tashkent 2016. P. 96-97.
6. Bala B. et al. Solar drying of pineapple using solar tunnel dryer Renewable Energy, 2003. Vol. 28. p. 183-190.
7. Safarov J.E., Sultanova Sh.A., Jumaev B.M. Texnologicheskiy protsess proizvodstva sushenyx lekarstvennyx trav. // Vestnik TashGTU, №2. 2015. S.164-167.