UA61463A - Solar drying chamber - Google Patents

Abstract

The solar drying chamber has transparent front (the upper inclined and vertical) and side walls, and the back heat-insulated wall, parabolic-cylindrical corrugated screens, and additional accumulator of radiation energy - common stone (gravel). In the dryer there is provided an air duct for circulating air, where there are placed three axial reversing fans and at the outlet - a pressure air duct with a gate. The back heat-insulated wall is lined with aluminum dull-black coating. The lower corrugated screen has perforated openings, rectangular in shape, for uniform distribution of heated air in length and height of the pile. The transparent walls of the frame structure with double glazing, together with hollow collector and corrugated black screen form the solar air heater.

Description

Description of the invention

The invention relates to the technique of drying wood and can be used for drying lumber 2 (planks, blanks, packing boards, etc.) and its sheet materials of plant origin (peeled and planed veneer, cardboard, wood fiber boards).

Depletion of reserves of traditional types of fuel (coal, oil, natural gas) for obtaining technical sources of energy (steam, electricity) and the release of prices for these energy carriers in Ukraine caused the need to find and use non-traditional and environmentally friendly types of energy for drying massive 70 wood . In connection with this, the use of solar energy for the intensification of wood drying processes in combination with purely atmospheric (natural) drying in stacks and traditional drying in convective calorific dryers acquires great importance and importance.

In recent decades, solar drying of wood in special chambers has become widely used in

Canada, Germany, Poland, the Czech Republic, Belarus, Russia, Bulgaria, that is, in countries with a temperate climate. 12 In particular, St. Nikolov and his colleagues |1), noting the great efficiency of using solar energy in combination with other types of technical energy, suggest using a two-way, 12 stacked (6x1.2x2.4 m), two-zone drying chamber (37x3.1x5 .4 m), in which the main element is an air-type solar collector system.

The upper transparent wall is inclined vertically at an angle of 4227, and the lower front wall is vertical. The back and side walls are metal panels sheathed in aluminum and coated in matte black. In the first zone of the dryer, air circulation was carried out with the help of 12 Mo 6 axial fans with a total installed capacity of 13.2 kW, and the electric motors themselves were located in the circulation channel. Circulation speed - 3...4 m/s. The supply and exhaust ducts were located in the rear insulated wall. In the middle zone there are three fans vertically, and in the second zone there are six vertically placed fans. In the 7279 last zone, there were four stacks, the installation of a steam heating system for drying wood from 3 to 8...1295 humidity is foreseen. The authors state a decrease of 3095% in thermal energy consumption and the possibility of ensuring year-round operation of the drying chamber in combination with other types of technical fuel energy.

The disadvantages of this invention are the large capacity of the chamber itself, which requires simultaneous loading of a sufficiently large amount of wood of the same species, thickness, initial moisture content, as well as significant costs, both (se) of material for the manufacture of the dryer itself, and steam energy to ensure the drying process.

The closest in essence is the dryer (prototype) proposed by the author (21), in which the air collector on one side is transparent, and the other is a heat-insulated ferrous metal surface. The air layer between the transparent wall and the heat-insulating material plays the role of an insulating layer radiating collector, where selective radiating surfaces were used as a collector. The chamber with dimensions of 38.5x10.2x8.9 m is a continuous action chamber, a two-way, 18-stack dryer (4.0x3.9x4 m). The chamber itself has an asymmetrical section, the size of which depends on the angle of inclination of the southern transparent wall (the angle of inclination itself is equal to 35...452). The dryer is conventionally divided into 9 zones, each of which is separated from each other by movable « 20 aluminum screens, which allows each zone to work independently dryers and use different drying modes. 18 Mo18 axial fans (two in each zone) are mounted on a reinforced concrete base on the north side of each chamber zone, and e electric motors are located in the control corridor. At the same time, the chamber is bulky, requires the simultaneous loading of large volumes of drying (184.4 m of conventional material), for drying from humidity 25 to 1095 requires significant costs of heat (up to 70103 MJ) and power electricity, which significantly reduces the efficiency of drying lumber.

Ge") Therefore, the above-mentioned shortcomings set before us the task of developing a rational design of a solar dryer, which would exclude the use of steam power with a simultaneous reduction in the drying time of wood and - ensuring continuous drying intensity with full preservation of structural and mechanical properties. The goal is achieved by the fact that the dryer (see fig.), which is a prefabricated panel structure (size 7.0x3.8x25 m), includes four transparent panels (front upper 2 and vertical 1 and two b side panels) and one rear heat-insulated panel 3, which is lined with an aluminum coating painted black on the inside, and with a metal sheet (construction steel 20) on the outside. Window glass is used as a transparent material, although the use of polymer films (for example, polypropylene,

PP-PE-90/10, Sarap, PVC-M-1, etc.).

The transparent walls are a frame structure in which there are two layers of silicate glass (limestone-sodium), which transmits 90...98956 of solar radiation; that is, the walls of the drying chamber facing the Sun have a box-like shape with double glazing and special air ducts. For periodic mixing of the heated air in the chamber, three reversible axial fans 4 are used, which are turned on every hour for 10 minutes, with a set power of 0.85-1.0 kW. To regulate the relative humidity of the air in the chamber, an exhaust channel 11 with a shutter is used, which is mounted in the thermally insulated (northern) wall З and through which the exhaust air is released into the atmosphere. Fresh air enters the chamber through leaks in the chamber enclosure. The air collector 5 is a blackened metal hollow frame, the upper wall of which is parallel to the upper front (southern) panel and forms an air duct with the latter, where fans 4 are installed. The angle of inclination of the upper front wall depends on the season and is: 65 In summer 479, and in winter 409 (the magnitude of the angle of inclination is regulated by the height of the Sun above the Earth's surface, depending on the season). To accumulate solar energy and ensure the operation of the dryer at night, we use corrugated screens 6 and 7, made of asbestos sheet (infrared emission coefficient equal to 0.96) or asbestos cardboard (the degree of blackness ranges from 0.93 to 0.95) .

The parabolo-cylindrical shape of the screen 6 and 7 allows you to accumulate solar energy regardless of the height of the Sun above the horizon, that is, its trajectory and leads to additional accumulation of thermal energy. Screen 7 is made in the form of a perforated sheet with rectangular holes (the number of holes is calculated depending on the volume of circulating air and the intensity of drying) and is designed to equalize the air speed along the height and length of the chamber from the heating side, i.e. the entry of the drying agent into the stack (see .

Fig.). To equalize the speed on the other side, screen 9 is used. 70 Two stacks (6.5x1.4x2.0 m) of lumber 8 are loaded directly through the front wall 1 with the help of an electric crane or a loader (it is possible to install a rail path and load through one of the side ( end) walls of the chamber).

In order to ensure a constant density of irradiation of the upper transparent wall 2 and a constant intensity of wood drying, we have provided for the use of movable flat reflectors 10. The reflector /5 is a wooden frame structure to which aluminum foil is attached, the reflection coefficient of incident solar radiation varies in in the range 0.90...0.981 (ZI.

As an additional source of accumulation of solar radiation, ordinary stones (gravel) are also used, covered with a black-matte color and lining the bottom of the chamber.

SOURCES

1. St. Nikolov, I. Dragozov, N. Terziev. Continuously operating solar wood dryer //

Woodworking and furniture industry, 1988. - Mo4. - P. 6-8. 2. Al-Haddat M. Slcheva dryer for wood // Woodworking and furniture industry, 1978. - Mo4. - b. 239-241 Pp

Z. Emissive properties of solid materials: Reference book. Under the municipality ed. A. E. Scheindlin. - M.:

Znergia, 1974.-472 p. "

Claims (1)

The formula of the invention is a solar drying chamber containing transparent front (upper inclined and vertical) and side walls, as well as a back heat-insulated (minwat) wall (panel), lined with aluminum matte black coating, and), which differs in that it contains parabolocylindrical corrugated screens that ensure the constant absorption of solar radiation regardless of the sun's height above the horizon, one of which (the lower one) has rectangular perforated holes for the uniform distribution of heated air along the length and height of the stack, as well as an additional radiation energy accumulator - ordinary stones (gravel), the solar dryer has an air duct with circulating air, in which three axial reversible fans are placed, and at the exit - a pressure air duct with a damper, transparent walls of the frame structure with double glazing together with a hollow collector and a corrugated blackened screen form a solar air heater. " - . and? (o) - sh» (o) syu» 60 b5